diff --git a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin.mps b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin.mps
index c6b68c08..6c4fc57d 100644
--- a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin.mps
+++ b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin.mps
@@ -1002,10 +1002,10 @@
                 <ref role="37wK5l" to="33ny:~ArrayList.&lt;init&gt;(int)" resolve="ArrayList" />
                 <node concept="2OqwBi" id="4TCblo5Noft" role="37wK5m">
                   <node concept="1rXfSq" id="4TCblo5ZmDR" role="2Oq$k0">
-                    <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                    <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                   </node>
                   <node concept="liA8E" id="4TCblo5Zn2F" role="2OqNvi">
-                    <ref role="37wK5l" to="33ny:~Collection.size():int" resolve="size" />
+                    <ref role="37wK5l" to="33ny:~List.size():int" resolve="size" />
                   </node>
                 </node>
                 <node concept="3uibUv" id="4TCblo5Nofw" role="1pMfVU">
@@ -1122,7 +1122,7 @@
             </node>
           </node>
           <node concept="1rXfSq" id="4TCblo5Znfk" role="1DdaDG">
-            <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+            <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
           </node>
         </node>
         <node concept="3clFbF" id="4TCblo5NpdK" role="3cqZAp">
@@ -1438,36 +1438,6 @@
       </node>
     </node>
     <node concept="2tJIrI" id="4TCblo5M5Qi" role="jymVt" />
-    <node concept="3clFb_" id="18cJbc16pY3" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="2aFKle" value="false" />
-      <property role="TrG5h" value="occurrenceArguments" />
-      <node concept="37vLTG" id="18cJbc16pY4" role="3clF46">
-        <property role="TrG5h" value="logicalContext" />
-        <node concept="3uibUv" id="18cJbc16pY5" role="1tU5fm">
-          <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
-        </node>
-      </node>
-      <node concept="3Tm1VV" id="4TCblo5M6d$" role="1B3o_S" />
-      <node concept="3uibUv" id="18cJbc16pY6" role="3clF45">
-        <ref role="3uigEE" to="33ny:~Collection" resolve="Collection" />
-        <node concept="3qTvmN" id="18cJbc16pY7" role="11_B2D" />
-      </node>
-      <node concept="3clFbS" id="18cJbc16pY8" role="3clF47">
-        <node concept="3clFbF" id="4TCblo5ZuZ2" role="3cqZAp">
-          <node concept="1rXfSq" id="4TCblo5ZuZ0" role="3clFbG">
-            <ref role="37wK5l" node="4TCblo5M6dy" resolve="instanceArguments" />
-            <node concept="37vLTw" id="4TCblo5Zvrm" role="37wK5m">
-              <ref role="3cqZAo" node="18cJbc16pY4" resolve="logicalContext" />
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="4TCblo5ZkZt" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
-    <node concept="2tJIrI" id="7IvepusY5Hm" role="jymVt" />
     <node concept="3clFb_" id="4sSe4$oZGZ9" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="patternPredicates" />
@@ -1724,5 +1694,195 @@
       </node>
     </node>
   </node>
+  <node concept="312cEu" id="5jCHAT2EKLb">
+    <property role="TrG5h" value="AbstractLogicSolver" />
+    <property role="1sVAO0" value="true" />
+    <node concept="2tJIrI" id="5jCHAT2EKMz" role="jymVt" />
+    <node concept="3clFb_" id="5jCHAT2EKMO" role="jymVt">
+      <property role="1EzhhJ" value="false" />
+      <property role="TrG5h" value="invocationArguments" />
+      <property role="DiZV1" value="false" />
+      <property role="od$2w" value="false" />
+      <node concept="3Tmbuc" id="5jCHAT2EKMP" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2EKMR" role="3clF45">
+        <ref role="3uigEE" to="33ny:~List" resolve="List" />
+        <node concept="3qTvmN" id="5jCHAT2EKMS" role="11_B2D" />
+      </node>
+      <node concept="37vLTG" id="5jCHAT2EKMT" role="3clF46">
+        <property role="TrG5h" value="predicate" />
+        <node concept="3uibUv" id="5jCHAT2EKMU" role="1tU5fm">
+          <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="5jCHAT2EKMV" role="3clF46">
+        <property role="TrG5h" value="logicalContext" />
+        <node concept="3uibUv" id="5jCHAT2EKMW" role="1tU5fm">
+          <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
+        </node>
+      </node>
+      <node concept="3clFbS" id="5jCHAT2EKMX" role="3clF47">
+        <node concept="3cpWs8" id="5jCHAT2ELP4" role="3cqZAp">
+          <node concept="3cpWsn" id="5jCHAT2ELP5" role="3cpWs9">
+            <property role="TrG5h" value="res" />
+            <node concept="3uibUv" id="5jCHAT2ELP6" role="1tU5fm">
+              <ref role="3uigEE" to="33ny:~ArrayList" resolve="ArrayList" />
+              <node concept="3uibUv" id="5jCHAT2ELP7" role="11_B2D">
+                <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+              </node>
+            </node>
+            <node concept="2ShNRf" id="5jCHAT2ELP8" role="33vP2m">
+              <node concept="1pGfFk" id="5jCHAT2ELP9" role="2ShVmc">
+                <ref role="37wK5l" to="33ny:~ArrayList.&lt;init&gt;(int)" resolve="ArrayList" />
+                <node concept="2OqwBi" id="5jCHAT2ELPa" role="37wK5m">
+                  <node concept="2OqwBi" id="5jCHAT2ENbi" role="2Oq$k0">
+                    <node concept="37vLTw" id="5jCHAT2ENp4" role="2Oq$k0">
+                      <ref role="3cqZAo" node="5jCHAT2EKMT" resolve="predicate" />
+                    </node>
+                    <node concept="liA8E" id="5jCHAT2ENbl" role="2OqNvi">
+                      <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
+                    </node>
+                  </node>
+                  <node concept="liA8E" id="5jCHAT2ELPc" role="2OqNvi">
+                    <ref role="37wK5l" to="33ny:~List.size():int" resolve="size" />
+                  </node>
+                </node>
+                <node concept="3uibUv" id="5jCHAT2ELPd" role="1pMfVU">
+                  <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="1DcWWT" id="5jCHAT2ELPe" role="3cqZAp">
+          <node concept="3clFbS" id="5jCHAT2ELPf" role="2LFqv$">
+            <node concept="3clFbJ" id="5jCHAT2ELPg" role="3cqZAp">
+              <node concept="3eNFk2" id="5jCHAT2ELPh" role="3eNLev">
+                <node concept="2ZW3vV" id="5jCHAT2ELPi" role="3eO9$A">
+                  <node concept="3uibUv" id="5jCHAT2ELPj" role="2ZW6by">
+                    <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  </node>
+                  <node concept="37vLTw" id="5jCHAT2ELPk" role="2ZW6bz">
+                    <ref role="3cqZAo" node="5jCHAT2ELPR" resolve="a" />
+                  </node>
+                </node>
+                <node concept="3clFbS" id="5jCHAT2ELPl" role="3eOfB_">
+                  <node concept="3clFbF" id="5jCHAT2ELPm" role="3cqZAp">
+                    <node concept="2OqwBi" id="5jCHAT2ELPn" role="3clFbG">
+                      <node concept="37vLTw" id="5jCHAT2ELPo" role="2Oq$k0">
+                        <ref role="3cqZAo" node="5jCHAT2ELP5" resolve="res" />
+                      </node>
+                      <node concept="liA8E" id="5jCHAT2ELPp" role="2OqNvi">
+                        <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                        <node concept="2OqwBi" id="5jCHAT2ELPq" role="37wK5m">
+                          <node concept="37vLTw" id="5jCHAT2ELPr" role="2Oq$k0">
+                            <ref role="3cqZAo" node="5jCHAT2EKMV" resolve="logicalContext" />
+                          </node>
+                          <node concept="liA8E" id="5jCHAT2ELPs" role="2OqNvi">
+                            <ref role="37wK5l" to="bj13:~LogicalContext.variable(jetbrains.mps.logic.reactor.logical.MetaLogical):jetbrains.mps.logic.reactor.logical.Logical" resolve="variable" />
+                            <node concept="10QFUN" id="5jCHAT2ELPt" role="37wK5m">
+                              <node concept="37vLTw" id="5jCHAT2ELPu" role="10QFUP">
+                                <ref role="3cqZAo" node="5jCHAT2ELPR" resolve="a" />
+                              </node>
+                              <node concept="3uibUv" id="5jCHAT2ELPv" role="10QFUM">
+                                <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                                <node concept="3uibUv" id="5jCHAT2ELPw" role="11_B2D">
+                                  <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                                </node>
+                              </node>
+                            </node>
+                          </node>
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                  <node concept="3clFbH" id="5jCHAT2ELPx" role="3cqZAp" />
+                </node>
+              </node>
+              <node concept="3clFbS" id="5jCHAT2ELPy" role="3clFbx">
+                <node concept="3clFbF" id="5jCHAT2ELPz" role="3cqZAp">
+                  <node concept="2OqwBi" id="5jCHAT2ELP$" role="3clFbG">
+                    <node concept="37vLTw" id="5jCHAT2ELP_" role="2Oq$k0">
+                      <ref role="3cqZAo" node="5jCHAT2ELP5" resolve="res" />
+                    </node>
+                    <node concept="liA8E" id="5jCHAT2ELPA" role="2OqNvi">
+                      <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                      <node concept="2YIFZM" id="5jCHAT2ELPB" role="37wK5m">
+                        <ref role="37wK5l" node="4TCblo5NqWF" resolve="instantiateMetaLogicals" />
+                        <ref role="1Pybhc" node="677NV565N1x" resolve="LogicalUtil" />
+                        <node concept="10QFUN" id="5jCHAT2ELPC" role="37wK5m">
+                          <node concept="3uibUv" id="5jCHAT2ELPD" role="10QFUM">
+                            <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                          </node>
+                          <node concept="37vLTw" id="5jCHAT2ELPE" role="10QFUP">
+                            <ref role="3cqZAo" node="5jCHAT2ELPR" resolve="a" />
+                          </node>
+                        </node>
+                        <node concept="37vLTw" id="5jCHAT2ELPF" role="37wK5m">
+                          <ref role="3cqZAo" node="5jCHAT2EKMV" resolve="logicalContext" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                </node>
+                <node concept="3clFbH" id="5jCHAT2ELPG" role="3cqZAp" />
+              </node>
+              <node concept="2ZW3vV" id="5jCHAT2ELPH" role="3clFbw">
+                <node concept="3uibUv" id="5jCHAT2ELPI" role="2ZW6by">
+                  <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                </node>
+                <node concept="37vLTw" id="5jCHAT2ELPJ" role="2ZW6bz">
+                  <ref role="3cqZAo" node="5jCHAT2ELPR" resolve="a" />
+                </node>
+              </node>
+              <node concept="9aQIb" id="5jCHAT2ELPK" role="9aQIa">
+                <node concept="3clFbS" id="5jCHAT2ELPL" role="9aQI4">
+                  <node concept="3clFbF" id="5jCHAT2ELPM" role="3cqZAp">
+                    <node concept="2OqwBi" id="5jCHAT2ELPN" role="3clFbG">
+                      <node concept="37vLTw" id="5jCHAT2ELPO" role="2Oq$k0">
+                        <ref role="3cqZAo" node="5jCHAT2ELP5" resolve="res" />
+                      </node>
+                      <node concept="liA8E" id="5jCHAT2ELPP" role="2OqNvi">
+                        <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                        <node concept="37vLTw" id="5jCHAT2ELPQ" role="37wK5m">
+                          <ref role="3cqZAo" node="5jCHAT2ELPR" resolve="a" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3cpWsn" id="5jCHAT2ELPR" role="1Duv9x">
+            <property role="TrG5h" value="a" />
+            <node concept="3uibUv" id="5jCHAT2ELPS" role="1tU5fm">
+              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+            </node>
+          </node>
+          <node concept="2OqwBi" id="5jCHAT2ENRR" role="1DdaDG">
+            <node concept="37vLTw" id="5jCHAT2EOmY" role="2Oq$k0">
+              <ref role="3cqZAo" node="5jCHAT2EKMT" resolve="predicate" />
+            </node>
+            <node concept="liA8E" id="5jCHAT2ENRU" role="2OqNvi">
+              <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="5jCHAT2ELPU" role="3cqZAp">
+          <node concept="37vLTw" id="5jCHAT2ELPV" role="3clFbG">
+            <ref role="3cqZAo" node="5jCHAT2ELP5" resolve="res" />
+          </node>
+        </node>
+      </node>
+      <node concept="2AHcQZ" id="5jCHAT2EKMY" role="2AJF6D">
+        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jCHAT2EKMC" role="jymVt" />
+    <node concept="3Tm1VV" id="5jCHAT2EKLc" role="1B3o_S" />
+    <node concept="3uibUv" id="5jCHAT2EKMi" role="1zkMxy">
+      <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
+    </node>
+  </node>
 </model>
 
diff --git a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/predicate.mps b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/predicate.mps
index 60d4678f..cc8b26ec 100644
--- a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/predicate.mps
+++ b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/predicate.mps
@@ -158,13 +158,9 @@
       </concept>
       <concept id="1212685548494" name="jetbrains.mps.baseLanguage.structure.ClassCreator" flags="nn" index="1pGfFk" />
       <concept id="1107461130800" name="jetbrains.mps.baseLanguage.structure.Classifier" flags="ng" index="3pOWGL">
-        <property id="521412098689998745" name="nonStatic" index="2bfB8j" />
         <child id="5375687026011219971" name="member" index="jymVt" unordered="true" />
       </concept>
       <concept id="1171903607971" name="jetbrains.mps.baseLanguage.structure.WildCardType" flags="in" index="3qTvmN" />
-      <concept id="1171903916106" name="jetbrains.mps.baseLanguage.structure.UpperBoundType" flags="in" index="3qUE_q">
-        <child id="1171903916107" name="bound" index="3qUE_r" />
-      </concept>
       <concept id="7812454656619025416" name="jetbrains.mps.baseLanguage.structure.MethodDeclaration" flags="ng" index="1rXfSm">
         <property id="8355037393041754995" name="isNative" index="2aFKle" />
       </concept>
@@ -195,9 +191,6 @@
       <concept id="1146644602865" name="jetbrains.mps.baseLanguage.structure.PublicVisibility" flags="nn" index="3Tm1VV" />
       <concept id="1146644623116" name="jetbrains.mps.baseLanguage.structure.PrivateVisibility" flags="nn" index="3Tm6S6" />
       <concept id="1146644641414" name="jetbrains.mps.baseLanguage.structure.ProtectedVisibility" flags="nn" index="3Tmbuc" />
-      <concept id="1116615150612" name="jetbrains.mps.baseLanguage.structure.ClassifierClassExpression" flags="nn" index="3VsKOn">
-        <reference id="1116615189566" name="classifier" index="3VsUkX" />
-      </concept>
     </language>
     <language id="760a0a8c-eabb-4521-8bfd-65db761a9ba3" name="jetbrains.mps.baseLanguage.logging">
       <concept id="1167227138527" name="jetbrains.mps.baseLanguage.logging.structure.LogStatement" flags="nn" index="34ab3g">
@@ -271,36 +264,6 @@
         <node concept="3qTvmN" id="7rf49NglNci" role="11_B2D" />
       </node>
     </node>
-    <node concept="2tJIrI" id="5uFPQ7BZjbz" role="jymVt" />
-    <node concept="3clFb_" id="4TCblo5Mg6d" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="2aFKle" value="false" />
-      <property role="TrG5h" value="invocationArguments" />
-      <node concept="37vLTG" id="4TCblo5Nrp7" role="3clF46">
-        <property role="TrG5h" value="logicalContext" />
-        <node concept="3uibUv" id="4TCblo5Nrr2" role="1tU5fm">
-          <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
-        </node>
-      </node>
-      <node concept="3Tm1VV" id="4TCblo5Mg6f" role="1B3o_S" />
-      <node concept="3uibUv" id="7rf49NglT9i" role="3clF45">
-        <ref role="3uigEE" to="33ny:~List" resolve="List" />
-        <node concept="3qTvmN" id="7rf49NglTG$" role="11_B2D" />
-      </node>
-      <node concept="3clFbS" id="4TCblo5Mg6j" role="3clF47">
-        <node concept="3clFbF" id="4TCblo5Zx$M" role="3cqZAp">
-          <node concept="1rXfSq" id="4TCblo5Zx$K" role="3clFbG">
-            <ref role="37wK5l" to="yg8f:4TCblo5M6dy" resolve="instanceArguments" />
-            <node concept="37vLTw" id="4TCblo5Zy07" role="37wK5m">
-              <ref role="3cqZAo" node="4TCblo5Nrp7" resolve="logicalContext" />
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="4TCblo5Mg_F" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
     <node concept="2tJIrI" id="4TCblo5MfR_" role="jymVt" />
     <node concept="3clFb_" id="6Kcfpq7B8WD" role="jymVt">
       <property role="1EzhhJ" value="false" />
@@ -308,9 +271,7 @@
       <property role="DiZV1" value="false" />
       <property role="IEkAT" value="false" />
       <node concept="3Tm1VV" id="6Kcfpq7B8WE" role="1B3o_S" />
-      <node concept="3uibUv" id="6Kcfpq7B8WG" role="3clF45">
-        <ref role="3uigEE" to="wyt6:~String" resolve="String" />
-      </node>
+      <node concept="17QB3L" id="5jCHAT2VZ5B" role="3clF45" />
       <node concept="3clFbS" id="6Kcfpq7B8WH" role="3clF47">
         <node concept="3clFbF" id="6Kcfpq7B99k" role="3cqZAp">
           <node concept="2OqwBi" id="5uFPQ7BZfDt" role="3clFbG">
@@ -556,16 +517,41 @@
     <property role="TrG5h" value="UnificationPredicate" />
     <node concept="2tJIrI" id="5uFPQ7C29se" role="jymVt" />
     <node concept="3Tm1VV" id="2GO7tyJVmP5" role="1B3o_S" />
-    <node concept="Wx3nA" id="2GO7tyJVob6" role="jymVt">
-      <property role="TrG5h" value="INFIX_UNI" />
-      <property role="3TUv4t" value="true" />
-      <node concept="3Tm1VV" id="2GO7tyJVob7" role="1B3o_S" />
-      <node concept="17QB3L" id="2GO7tyJVob8" role="1tU5fm" />
-      <node concept="Xl_RD" id="2GO7tyJVob9" role="33vP2m">
-        <property role="Xl_RC" value="===" />
+    <node concept="2YIFZL" id="5jCHAT29qgV" role="jymVt">
+      <property role="TrG5h" value="unifies" />
+      <node concept="37vLTG" id="5jCHAT29qMq" role="3clF46">
+        <property role="TrG5h" value="left" />
+        <node concept="3uibUv" id="5jCHAT29qMr" role="1tU5fm">
+          <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="5jCHAT29qMs" role="3clF46">
+        <property role="TrG5h" value="right" />
+        <node concept="3uibUv" id="5jCHAT29qMt" role="1tU5fm">
+          <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+        </node>
+      </node>
+      <node concept="3uibUv" id="5jCHAT29qnP" role="3clF45">
+        <ref role="3uigEE" node="2GO7tyJVmP4" resolve="UnificationPredicate" />
+      </node>
+      <node concept="3Tm1VV" id="5jCHAT29qgY" role="1B3o_S" />
+      <node concept="3clFbS" id="5jCHAT29qgZ" role="3clF47">
+        <node concept="3clFbF" id="5jCHAT29qU2" role="3cqZAp">
+          <node concept="2ShNRf" id="5jCHAT29qU0" role="3clFbG">
+            <node concept="1pGfFk" id="5jCHAT29r5d" role="2ShVmc">
+              <ref role="37wK5l" node="4xBopTzmopz" resolve="UnificationPredicate" />
+              <node concept="37vLTw" id="5jCHAT29rbn" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT29qMq" resolve="left" />
+              </node>
+              <node concept="37vLTw" id="5jCHAT29rcn" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT29qMs" resolve="right" />
+              </node>
+            </node>
+          </node>
+        </node>
       </node>
     </node>
-    <node concept="2tJIrI" id="2GO7tyJVqjK" role="jymVt" />
+    <node concept="2tJIrI" id="5jCHAT29rrQ" role="jymVt" />
     <node concept="3clFbW" id="4xBopTzmopz" role="jymVt">
       <node concept="37vLTG" id="5uFPQ7C29xx" role="3clF46">
         <property role="TrG5h" value="left" />
@@ -622,6 +608,15 @@
         <property role="Xl_RC" value="uni" />
       </node>
     </node>
+    <node concept="Wx3nA" id="2GO7tyJVob6" role="jymVt">
+      <property role="TrG5h" value="INFIX_UNI" />
+      <property role="3TUv4t" value="true" />
+      <node concept="3Tm1VV" id="2GO7tyJVob7" role="1B3o_S" />
+      <node concept="17QB3L" id="2GO7tyJVob8" role="1tU5fm" />
+      <node concept="Xl_RD" id="2GO7tyJVob9" role="33vP2m">
+        <property role="Xl_RC" value="===" />
+      </node>
+    </node>
     <node concept="Wx3nA" id="5uFPQ7C29mw" role="jymVt">
       <property role="3TUv4t" value="true" />
       <property role="TrG5h" value="UNI_SYM" />
@@ -716,13 +711,38 @@
   <node concept="312cEu" id="3HJTsBn4kk_">
     <property role="TrG5h" value="EqualsPredicate" />
     <node concept="2tJIrI" id="3HJTsBn4kQm" role="jymVt" />
-    <node concept="Wx3nA" id="3HJTsBn4kQn" role="jymVt">
-      <property role="TrG5h" value="INFIX_EQ" />
-      <property role="3TUv4t" value="true" />
-      <node concept="3Tm1VV" id="3HJTsBn4kQo" role="1B3o_S" />
-      <node concept="17QB3L" id="3HJTsBn4kQp" role="1tU5fm" />
-      <node concept="Xl_RD" id="3HJTsBn4kQq" role="33vP2m">
-        <property role="Xl_RC" value="==" />
+    <node concept="2YIFZL" id="5jCHAT2iqus" role="jymVt">
+      <property role="TrG5h" value="eq" />
+      <node concept="37vLTG" id="5jCHAT2ir1t" role="3clF46">
+        <property role="TrG5h" value="left" />
+        <node concept="3uibUv" id="5jCHAT2ircQ" role="1tU5fm">
+          <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="5jCHAT2iror" role="3clF46">
+        <property role="TrG5h" value="right" />
+        <node concept="3uibUv" id="5jCHAT2irzS" role="1tU5fm">
+          <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+        </node>
+      </node>
+      <node concept="3uibUv" id="5jCHAT2iqEZ" role="3clF45">
+        <ref role="3uigEE" node="3HJTsBn4kk_" resolve="EqualsPredicate" />
+      </node>
+      <node concept="3Tm1VV" id="5jCHAT2iquv" role="1B3o_S" />
+      <node concept="3clFbS" id="5jCHAT2iquw" role="3clF47">
+        <node concept="3clFbF" id="5jCHAT2irKd" role="3cqZAp">
+          <node concept="2ShNRf" id="5jCHAT2irKb" role="3clFbG">
+            <node concept="1pGfFk" id="5jCHAT2irVw" role="2ShVmc">
+              <ref role="37wK5l" node="4xBopTzo_Q1" resolve="EqualsPredicate" />
+              <node concept="37vLTw" id="5jCHAT2is1N" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT2ir1t" resolve="left" />
+              </node>
+              <node concept="37vLTw" id="5jCHAT2is2W" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT2iror" resolve="right" />
+              </node>
+            </node>
+          </node>
+        </node>
       </node>
     </node>
     <node concept="2tJIrI" id="2UGjFq4gG5y" role="jymVt" />
@@ -783,6 +803,15 @@
         <property role="Xl_RC" value="eq" />
       </node>
     </node>
+    <node concept="Wx3nA" id="3HJTsBn4kQn" role="jymVt">
+      <property role="TrG5h" value="INFIX_EQ" />
+      <property role="3TUv4t" value="true" />
+      <node concept="3Tm1VV" id="3HJTsBn4kQo" role="1B3o_S" />
+      <node concept="17QB3L" id="3HJTsBn4kQp" role="1tU5fm" />
+      <node concept="Xl_RD" id="3HJTsBn4kQq" role="33vP2m">
+        <property role="Xl_RC" value="==" />
+      </node>
+    </node>
     <node concept="Wx3nA" id="5uFPQ7C23RV" role="jymVt">
       <property role="3TUv4t" value="true" />
       <property role="TrG5h" value="EQ_SYM" />
@@ -1115,8 +1144,8 @@
     <node concept="3clFbW" id="3F6vMxqo1c$" role="jymVt">
       <node concept="37vLTG" id="3F6vMxqo1cY" role="3clF46">
         <property role="TrG5h" value="javaExpressionSolver" />
-        <node concept="3uibUv" id="3F6vMxqo1dR" role="1tU5fm">
-          <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+        <node concept="3uibUv" id="5jCHAT2qKEp" role="1tU5fm">
+          <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
         </node>
       </node>
       <node concept="3cqZAl" id="3F6vMxqo1cA" role="3clF45" />
@@ -1127,7 +1156,7 @@
             <node concept="2OqwBi" id="3F6vMxqo1vB" role="37vLTJ">
               <node concept="Xjq3P" id="3F6vMxqo1wG" role="2Oq$k0" />
               <node concept="2OwXpG" id="3F6vMxqo1vE" role="2OqNvi">
-                <ref role="2Oxat5" node="3F6vMxqo1jQ" resolve="myJavaExpressionSolver" />
+                <ref role="2Oxat5" node="3F6vMxqo1jQ" resolve="javaExpressionSolver" />
               </node>
             </node>
             <node concept="37vLTw" id="3F6vMxqo1k0" role="37vLTx">
@@ -1165,7 +1194,7 @@
               <node concept="2OqwBi" id="7ISVfSIVrQ" role="3clFbG">
                 <node concept="Xjq3P" id="2tcGHBEecgK" role="2Oq$k0" />
                 <node concept="liA8E" id="7ISVfSIVsU" role="2OqNvi">
-                  <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                  <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                   <node concept="10QFUN" id="7ISVfSIYFl" role="37wK5m">
                     <node concept="3uibUv" id="7ISVfSIYFj" role="10QFUM">
                       <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1219,7 +1248,7 @@
                 <node concept="2OqwBi" id="7ISVfSIYOw" role="3clFbG">
                   <node concept="Xjq3P" id="2tcGHBEecj3" role="2Oq$k0" />
                   <node concept="liA8E" id="7ISVfSIYOy" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                     <node concept="10QFUN" id="7ISVfSIYOz" role="37wK5m">
                       <node concept="3uibUv" id="7ISVfSIYO$" role="10QFUM">
                         <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1257,7 +1286,7 @@
                 <node concept="2OqwBi" id="7ISVfSIZhn" role="3clFbG">
                   <node concept="Xjq3P" id="2tcGHBEeclc" role="2Oq$k0" />
                   <node concept="liA8E" id="7ISVfSIZhp" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                     <node concept="10QFUN" id="7ISVfSIZhq" role="37wK5m">
                       <node concept="3uibUv" id="7ISVfSIZhr" role="10QFUM">
                         <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1295,7 +1324,7 @@
                 <node concept="2OqwBi" id="7ISVfSJ2P7" role="3clFbG">
                   <node concept="Xjq3P" id="2tcGHBEecmS" role="2Oq$k0" />
                   <node concept="liA8E" id="7ISVfSJ2P9" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                     <node concept="10QFUN" id="7ISVfSJ2Pa" role="37wK5m">
                       <node concept="3uibUv" id="7ISVfSJ2Pb" role="10QFUM">
                         <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1333,7 +1362,7 @@
                 <node concept="2OqwBi" id="7ISVfSJ30o" role="3clFbG">
                   <node concept="Xjq3P" id="2tcGHBEecoN" role="2Oq$k0" />
                   <node concept="liA8E" id="7ISVfSJ30q" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                     <node concept="10QFUN" id="7ISVfSJ30r" role="37wK5m">
                       <node concept="3uibUv" id="7ISVfSJ30s" role="10QFUM">
                         <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1371,7 +1400,7 @@
                 <node concept="2OqwBi" id="7rf49NglcJd" role="3clFbG">
                   <node concept="Xjq3P" id="7rf49NglcFk" role="2Oq$k0" />
                   <node concept="liA8E" id="7rf49NglcR4" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                     <node concept="10QFUN" id="7rf49Ngld7I" role="37wK5m">
                       <node concept="3uibUv" id="7rf49Ngld7G" role="10QFUM">
                         <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1397,7 +1426,7 @@
               <node concept="3clFbJ" id="1ggxSI7xGoB" role="3cqZAp">
                 <node concept="3y3z36" id="4psy6tqsyWz" role="3clFbw">
                   <node concept="37vLTw" id="3F6vMxqoq$n" role="3uHU7B">
-                    <ref role="3cqZAo" node="3F6vMxqo1jQ" resolve="myJavaExpressionSolver" />
+                    <ref role="3cqZAo" node="3F6vMxqo1jQ" resolve="javaExpressionSolver" />
                   </node>
                   <node concept="10Nm6u" id="1ggxSI7xGtI" role="3uHU7w" />
                 </node>
@@ -1406,7 +1435,7 @@
                     <node concept="2OqwBi" id="1ggxSI7qGPQ" role="3clFbG">
                       <node concept="Xjq3P" id="1ggxSI7qGPR" role="2Oq$k0" />
                       <node concept="liA8E" id="1ggxSI7qGPS" role="2OqNvi">
-                        <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                        <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                         <node concept="10QFUN" id="1ggxSI7qGPT" role="37wK5m">
                           <node concept="3uibUv" id="1ggxSI7qGPU" role="10QFUM">
                             <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1419,7 +1448,7 @@
                           <node concept="1pGfFk" id="1ggxSI7xcbQ" role="2ShVmc">
                             <ref role="37wK5l" to="omn0:6MYr6Jx1c2W" resolve="JavaSolver" />
                             <node concept="37vLTw" id="3F6vMxqosAS" role="37wK5m">
-                              <ref role="3cqZAo" node="3F6vMxqo1jQ" resolve="myJavaExpressionSolver" />
+                              <ref role="3cqZAo" node="3F6vMxqo1jQ" resolve="javaExpressionSolver" />
                             </node>
                           </node>
                         </node>
@@ -1440,7 +1469,7 @@
                       <node concept="2OqwBi" id="4psy6tqszLX" role="3clFbG">
                         <node concept="Xjq3P" id="4psy6tqszLY" role="2Oq$k0" />
                         <node concept="liA8E" id="4psy6tqszLZ" role="2OqNvi">
-                          <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.Solver):void" resolve="registerSolver" />
+                          <ref role="37wK5l" to="w7la:~SessionSolver.registerSolver(jetbrains.mps.logic.reactor.program.PredicateSymbol,jetbrains.mps.logic.reactor.evaluation.AbstractSolver):void" resolve="registerSolver" />
                           <node concept="10QFUN" id="4psy6tqszM0" role="37wK5m">
                             <node concept="3uibUv" id="4psy6tqszM1" role="10QFUM">
                               <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
@@ -1497,212 +1526,15 @@
       </node>
     </node>
     <node concept="2tJIrI" id="3F6vMxqo1bP" role="jymVt" />
-    <node concept="3clFb_" id="3F6vMxqottl" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="solverClass" />
-      <property role="od$2w" value="false" />
-      <property role="DiZV1" value="false" />
-      <property role="2aFKle" value="false" />
-      <node concept="3Tm1VV" id="3F6vMxqottn" role="1B3o_S" />
-      <node concept="3uibUv" id="3F6vMxqotto" role="3clF45">
-        <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
-        <node concept="3qUE_q" id="3F6vMxqottp" role="11_B2D">
-          <node concept="3uibUv" id="3F6vMxqottq" role="3qUE_r">
-            <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
-          </node>
-        </node>
-      </node>
-      <node concept="37vLTG" id="3F6vMxqottr" role="3clF46">
-        <property role="TrG5h" value="symbol" />
-        <node concept="3uibUv" id="3F6vMxqotts" role="1tU5fm">
-          <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="3clFbS" id="3F6vMxqottt" role="3clF47">
-        <node concept="3clFbJ" id="2tcGHBEvbMP" role="3cqZAp">
-          <node concept="3clFbS" id="2tcGHBEvbMQ" role="3clFbx">
-            <node concept="3cpWs6" id="2tcGHBEvfUa" role="3cqZAp">
-              <node concept="3VsKOn" id="2tcGHBEvgfM" role="3cqZAk">
-                <ref role="3VsUkX" to="omn0:6GYQG_Spvw5" resolve="UnificationSolver" />
-              </node>
-            </node>
-            <node concept="3clFbH" id="2tcGHBEvgqn" role="3cqZAp" />
-          </node>
-          <node concept="2OqwBi" id="2tcGHBEvbN3" role="3clFbw">
-            <node concept="10M0yZ" id="2tcGHBEvbN4" role="2Oq$k0">
-              <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationPredicate" />
-              <ref role="3cqZAo" node="5uFPQ7C29mw" resolve="UNI_SYM" />
-            </node>
-            <node concept="liA8E" id="2tcGHBEvbN5" role="2OqNvi">
-              <ref role="37wK5l" to="av0y:~Symbol.equals(java.lang.Object):boolean" resolve="equals" />
-              <node concept="37vLTw" id="2tcGHBEvbN6" role="37wK5m">
-                <ref role="3cqZAo" node="3F6vMxqottr" resolve="symbol" />
-              </node>
-            </node>
-          </node>
-          <node concept="3eNFk2" id="2tcGHBEvbN7" role="3eNLev">
-            <node concept="2OqwBi" id="2tcGHBEvbN8" role="3eO9$A">
-              <node concept="10M0yZ" id="2tcGHBEvbN9" role="2Oq$k0">
-                <ref role="1PxDUh" node="3HJTsBn4kk_" resolve="EqualsPredicate" />
-                <ref role="3cqZAo" node="5uFPQ7C23RV" resolve="EQ_SYM" />
-              </node>
-              <node concept="liA8E" id="2tcGHBEvbNa" role="2OqNvi">
-                <ref role="37wK5l" to="av0y:~Symbol.equals(java.lang.Object):boolean" resolve="equals" />
-                <node concept="37vLTw" id="2tcGHBEvbNb" role="37wK5m">
-                  <ref role="3cqZAo" node="3F6vMxqottr" resolve="symbol" />
-                </node>
-              </node>
-            </node>
-            <node concept="3clFbS" id="2tcGHBEvbNc" role="3eOfB_">
-              <node concept="3cpWs6" id="2tcGHBEvgBd" role="3cqZAp">
-                <node concept="3VsKOn" id="2tcGHBEvh5M" role="3cqZAk">
-                  <ref role="3VsUkX" to="omn0:3HJTsBn4ogZ" resolve="EqualsSolver" />
-                </node>
-              </node>
-              <node concept="3clFbH" id="2tcGHBEvbNn" role="3cqZAp" />
-            </node>
-          </node>
-          <node concept="3eNFk2" id="2tcGHBEvbNo" role="3eNLev">
-            <node concept="2OqwBi" id="2tcGHBEvbNp" role="3eO9$A">
-              <node concept="10M0yZ" id="2tcGHBEvbNq" role="2Oq$k0">
-                <ref role="1PxDUh" node="6infEALAfer" resolve="AssertPredicate" />
-                <ref role="3cqZAo" node="5uFPQ7BZnLB" resolve="ASSERT_SYM" />
-              </node>
-              <node concept="liA8E" id="2tcGHBEvbNr" role="2OqNvi">
-                <ref role="37wK5l" to="av0y:~Symbol.equals(java.lang.Object):boolean" resolve="equals" />
-                <node concept="37vLTw" id="2tcGHBEvbNs" role="37wK5m">
-                  <ref role="3cqZAo" node="3F6vMxqottr" resolve="symbol" />
-                </node>
-              </node>
-            </node>
-            <node concept="3clFbS" id="2tcGHBEvbNt" role="3eOfB_">
-              <node concept="3cpWs6" id="2tcGHBEvhtS" role="3cqZAp">
-                <node concept="3VsKOn" id="2tcGHBEvhLT" role="3cqZAk">
-                  <ref role="3VsUkX" to="omn0:6infEALAKBG" resolve="AssertSolver" />
-                </node>
-              </node>
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     </node>
     <node concept="312cEg" id="3F6vMxqo1jQ" role="jymVt">
-      <property role="TrG5h" value="myJavaExpressionSolver" />
+      <property role="TrG5h" value="javaExpressionSolver" />
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-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2qKu7" role="1tU5fm">
+        <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
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diff --git a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/program.mps b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/program.mps
index a93eb5bd..320f92fe 100644
--- a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/program.mps
+++ b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/program.mps
@@ -1012,6 +1012,187 @@
         <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
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+    <node concept="2tJIrI" id="5jCHAT2R0T$" role="jymVt" />
+    <node concept="3clFb_" id="5jCHAT2QZ9K" role="jymVt">
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+      <property role="TrG5h" value="occurrenceArguments" />
+      <property role="DiZV1" value="false" />
+      <property role="od$2w" value="false" />
+      <node concept="3Tm1VV" id="5jCHAT2QZ9L" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2QZ9N" role="3clF45">
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+        <node concept="3qTvmN" id="5jCHAT2QZ9O" role="11_B2D" />
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+      <node concept="37vLTG" id="5jCHAT2QZ9P" role="3clF46">
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+      </node>
+      <node concept="37vLTG" id="5jCHAT2QZ9R" role="3clF46">
+        <property role="TrG5h" value="logicalContext" />
+        <node concept="3uibUv" id="5jCHAT2QZ9S" role="1tU5fm">
+          <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
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+          <node concept="3cpWsn" id="4TCblo5Nofq" role="3cpWs9">
+            <property role="TrG5h" value="res" />
+            <node concept="3uibUv" id="4TCblo5Noff" role="1tU5fm">
+              <ref role="3uigEE" to="33ny:~ArrayList" resolve="ArrayList" />
+              <node concept="3uibUv" id="4TCblo5Nofi" role="11_B2D">
+                <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
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+            <node concept="2ShNRf" id="4TCblo5Nofr" role="33vP2m">
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+                  <node concept="2OqwBi" id="5jCHAT2R4gj" role="2Oq$k0">
+                    <node concept="37vLTw" id="5jCHAT2R4td" role="2Oq$k0">
+                      <ref role="3cqZAo" node="5jCHAT2QZ9P" resolve="constraint" />
+                    </node>
+                    <node concept="liA8E" id="5jCHAT2R4gm" role="2OqNvi">
+                      <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
+                    </node>
+                  </node>
+                  <node concept="liA8E" id="4TCblo5Zn2F" role="2OqNvi">
+                    <ref role="37wK5l" to="33ny:~List.size():int" resolve="size" />
+                  </node>
+                </node>
+                <node concept="3uibUv" id="4TCblo5Nofw" role="1pMfVU">
+                  <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="1DcWWT" id="4TCblo5NoSa" role="3cqZAp">
+          <node concept="3clFbS" id="4TCblo5NoSc" role="2LFqv$">
+            <node concept="3clFbJ" id="4TCblo5Npl3" role="3cqZAp">
+              <node concept="3eNFk2" id="4TCblo5Z7hN" role="3eNLev">
+                <node concept="2ZW3vV" id="4TCblo5Z7_w" role="3eO9$A">
+                  <node concept="3uibUv" id="4TCblo5Z7CL" role="2ZW6by">
+                    <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  </node>
+                  <node concept="37vLTw" id="4TCblo5Z7xU" role="2ZW6bz">
+                    <ref role="3cqZAo" node="4TCblo5NoSd" resolve="a" />
+                  </node>
+                </node>
+                <node concept="3clFbS" id="4TCblo5Z7hP" role="3eOfB_">
+                  <node concept="3clFbF" id="4TCblo5Z7IR" role="3cqZAp">
+                    <node concept="2OqwBi" id="4TCblo5Z7IS" role="3clFbG">
+                      <node concept="37vLTw" id="4TCblo5Z7IT" role="2Oq$k0">
+                        <ref role="3cqZAo" node="4TCblo5Nofq" resolve="res" />
+                      </node>
+                      <node concept="liA8E" id="4TCblo5Z7IU" role="2OqNvi">
+                        <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                        <node concept="2OqwBi" id="4TCblo5Z8fU" role="37wK5m">
+                          <node concept="37vLTw" id="4TCblo5Z86K" role="2Oq$k0">
+                            <ref role="3cqZAo" node="5jCHAT2QZ9R" resolve="logicalContext" />
+                          </node>
+                          <node concept="liA8E" id="4TCblo5Z8s6" role="2OqNvi">
+                            <ref role="37wK5l" to="bj13:~LogicalContext.variable(jetbrains.mps.logic.reactor.logical.MetaLogical):jetbrains.mps.logic.reactor.logical.Logical" resolve="variable" />
+                            <node concept="10QFUN" id="4TCblo5Z8y1" role="37wK5m">
+                              <node concept="37vLTw" id="4TCblo5Z97c" role="10QFUP">
+                                <ref role="3cqZAo" node="4TCblo5NoSd" resolve="a" />
+                              </node>
+                              <node concept="3uibUv" id="4TCblo5Z8NB" role="10QFUM">
+                                <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                                <node concept="3uibUv" id="4TCblo5Z9P0" role="11_B2D">
+                                  <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                                </node>
+                              </node>
+                            </node>
+                          </node>
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                  <node concept="3clFbH" id="4TCblo5Z7FY" role="3cqZAp" />
+                </node>
+              </node>
+              <node concept="3clFbS" id="4TCblo5Npl5" role="3clFbx">
+                <node concept="3clFbF" id="4TCblo5NpB6" role="3cqZAp">
+                  <node concept="2OqwBi" id="4TCblo5NpQT" role="3clFbG">
+                    <node concept="37vLTw" id="4TCblo5NpB4" role="2Oq$k0">
+                      <ref role="3cqZAo" node="4TCblo5Nofq" resolve="res" />
+                    </node>
+                    <node concept="liA8E" id="4TCblo5NqAb" role="2OqNvi">
+                      <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                      <node concept="2YIFZM" id="4TCblo5Nr7d" role="37wK5m">
+                        <ref role="1Pybhc" to="yg8f:677NV565N1x" resolve="LogicalUtil" />
+                        <ref role="37wK5l" to="yg8f:4TCblo5NqWF" resolve="instantiateMetaLogicals" />
+                        <node concept="10QFUN" id="4TCblo5Nskr" role="37wK5m">
+                          <node concept="3uibUv" id="4TCblo5Nskp" role="10QFUM">
+                            <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                          </node>
+                          <node concept="37vLTw" id="4TCblo5NsuL" role="10QFUP">
+                            <ref role="3cqZAo" node="4TCblo5NoSd" resolve="a" />
+                          </node>
+                        </node>
+                        <node concept="37vLTw" id="4TCblo5NsHZ" role="37wK5m">
+                          <ref role="3cqZAo" node="5jCHAT2QZ9R" resolve="logicalContext" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                </node>
+                <node concept="3clFbH" id="4TCblo5Yuzk" role="3cqZAp" />
+              </node>
+              <node concept="2ZW3vV" id="4TCblo5NptX" role="3clFbw">
+                <node concept="3uibUv" id="4TCblo5NpxS" role="2ZW6by">
+                  <ref role="3uigEE" to="6exd:1bm7a6EXvsP" resolve="TreeForm" />
+                </node>
+                <node concept="37vLTw" id="4TCblo5Nppi" role="2ZW6bz">
+                  <ref role="3cqZAo" node="4TCblo5NoSd" resolve="a" />
+                </node>
+              </node>
+              <node concept="9aQIb" id="4TCblo5NsUE" role="9aQIa">
+                <node concept="3clFbS" id="4TCblo5NsUF" role="9aQI4">
+                  <node concept="3clFbF" id="4TCblo5Nt4I" role="3cqZAp">
+                    <node concept="2OqwBi" id="4TCblo5Ntkx" role="3clFbG">
+                      <node concept="37vLTw" id="4TCblo5Nt4H" role="2Oq$k0">
+                        <ref role="3cqZAo" node="4TCblo5Nofq" resolve="res" />
+                      </node>
+                      <node concept="liA8E" id="4TCblo5Nu3N" role="2OqNvi">
+                        <ref role="37wK5l" to="33ny:~ArrayList.add(java.lang.Object):boolean" resolve="add" />
+                        <node concept="37vLTw" id="4TCblo5Nuf1" role="37wK5m">
+                          <ref role="3cqZAo" node="4TCblo5NoSd" resolve="a" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3cpWsn" id="4TCblo5NoSd" role="1Duv9x">
+            <property role="TrG5h" value="a" />
+            <node concept="3uibUv" id="4TCblo5NoWE" role="1tU5fm">
+              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+            </node>
+          </node>
+          <node concept="2OqwBi" id="5jCHAT2R4NQ" role="1DdaDG">
+            <node concept="37vLTw" id="5jCHAT2R53E" role="2Oq$k0">
+              <ref role="3cqZAo" node="5jCHAT2QZ9P" resolve="constraint" />
+            </node>
+            <node concept="liA8E" id="5jCHAT2R4NT" role="2OqNvi">
+              <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="4TCblo5NpdK" role="3cqZAp">
+          <node concept="37vLTw" id="4TCblo5NpdI" role="3clFbG">
+            <ref role="3cqZAo" node="4TCblo5Nofq" resolve="res" />
+          </node>
+        </node>
+      </node>
+      <node concept="2AHcQZ" id="5jCHAT2QZ9U" role="2AJF6D">
+        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+      </node>
+    </node>
     <node concept="2tJIrI" id="aFQeb4jPwW" role="jymVt" />
     <node concept="3clFb_" id="5rhZO$TZwZl" role="jymVt">
       <property role="TrG5h" value="getLocalVarIndex" />
@@ -1252,11 +1433,11 @@
                         <ref role="3cqZAo" node="5uFPQ7BEo4w" resolve="cst" />
                       </node>
                       <node concept="liA8E" id="30XHGaOWeZv" role="2OqNvi">
-                        <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                        <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                       </node>
                     </node>
                     <node concept="liA8E" id="30XHGaOWfgx" role="2OqNvi">
-                      <ref role="37wK5l" to="33ny:~Collection.size():int" resolve="size" />
+                      <ref role="37wK5l" to="33ny:~List.size():int" resolve="size" />
                     </node>
                   </node>
                   <node concept="2OqwBi" id="7eGEHDlg3RX" role="3uHU7B">
@@ -1501,11 +1682,11 @@
                         <ref role="3cqZAo" node="5uFPQ7BEu6z" resolve="pred" />
                       </node>
                       <node concept="liA8E" id="30XHGaOWeEi" role="2OqNvi">
-                        <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                        <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                       </node>
                     </node>
                     <node concept="liA8E" id="30XHGaOWeVo" role="2OqNvi">
-                      <ref role="37wK5l" to="33ny:~Collection.size():int" resolve="size" />
+                      <ref role="37wK5l" to="33ny:~List.size():int" resolve="size" />
                     </node>
                   </node>
                   <node concept="2OqwBi" id="2pvEdquuFm4" role="3uHU7w">
@@ -1576,7 +1757,7 @@
               <ref role="3cqZAo" node="7eGEHDldphF" resolve="item" />
             </node>
             <node concept="liA8E" id="2KVRGowW$Kw" role="2OqNvi">
-              <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+              <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
             </node>
           </node>
         </node>
@@ -1971,7 +2152,7 @@
                   <ref role="3cqZAo" node="5rhZO$TZT5G" resolve="cst" />
                 </node>
                 <node concept="liA8E" id="5rhZO$TZT5F" role="2OqNvi">
-                  <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                  <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                 </node>
               </node>
             </node>
@@ -2043,7 +2224,7 @@
                   <ref role="3cqZAo" node="5rhZO$TZT69" resolve="cst" />
                 </node>
                 <node concept="liA8E" id="5rhZO$TZT68" role="2OqNvi">
-                  <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                  <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                 </node>
               </node>
             </node>
@@ -2399,7 +2580,7 @@
                       <ref role="3cqZAo" node="5rhZO$TZT8m" resolve="item" />
                     </node>
                     <node concept="liA8E" id="5rhZO$TZT8l" role="2OqNvi">
-                      <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.Collection" resolve="arguments" />
+                      <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
                     </node>
                   </node>
                 </node>
diff --git a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/solver.mps b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/solver.mps
index 9d1898d7..e7d0c397 100644
--- a/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/solver.mps
+++ b/logic/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/solver.mps
@@ -13,6 +13,7 @@
     <import index="yt73" ref="bbf5c548-7111-4a53-a117-cdefc664cf34/java:jetbrains.mps.unification(jetbrains.mps.logic.reactor/)" />
     <import index="33ny" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.util(JDK/)" />
     <import index="cxk7" ref="r:daa544a7-0a5c-49c0-a54c-4c2a5b4868aa(jetbrains.mps.logic.builtin.predicate)" />
+    <import index="yg8f" ref="r:e213377a-f1a7-4ba7-9d08-96bcb97ed8ce(jetbrains.mps.logic.builtin)" />
   </imports>
   <registry>
     <language id="f3061a53-9226-4cc5-a443-f952ceaf5816" name="jetbrains.mps.baseLanguage">
@@ -82,7 +83,6 @@
       <concept id="1068390468200" name="jetbrains.mps.baseLanguage.structure.FieldDeclaration" flags="ig" index="312cEg" />
       <concept id="1068390468198" name="jetbrains.mps.baseLanguage.structure.ClassConcept" flags="ig" index="312cEu">
         <property id="1075300953594" name="abstractClass" index="1sVAO0" />
-        <child id="1095933932569" name="implementedInterface" index="EKbjA" />
         <child id="1165602531693" name="superclass" index="1zkMxy" />
       </concept>
       <concept id="1068431474542" name="jetbrains.mps.baseLanguage.structure.VariableDeclaration" flags="ng" index="33uBYm">
@@ -169,9 +169,6 @@
       <concept id="1171903916106" name="jetbrains.mps.baseLanguage.structure.UpperBoundType" flags="in" index="3qUE_q">
         <child id="1171903916107" name="bound" index="3qUE_r" />
       </concept>
-      <concept id="7812454656619025416" name="jetbrains.mps.baseLanguage.structure.MethodDeclaration" flags="ng" index="1rXfSm">
-        <property id="8355037393041754995" name="isNative" index="2aFKle" />
-      </concept>
       <concept id="7812454656619025412" name="jetbrains.mps.baseLanguage.structure.LocalMethodCall" flags="nn" index="1rXfSq" />
       <concept id="1107535904670" name="jetbrains.mps.baseLanguage.structure.ClassifierType" flags="in" index="3uibUv">
         <reference id="1107535924139" name="classifier" index="3uigEE" />
@@ -223,104 +220,6 @@
   </registry>
   <node concept="312cEu" id="3HJTsBn4ogZ">
     <property role="TrG5h" value="EqualsSolver" />
-    <node concept="2tJIrI" id="5p8T3QHE7qu" role="jymVt" />
-    <node concept="3clFb_" id="2UGjFq4fUbF" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="predicate" />
-      <node concept="37vLTG" id="2UGjFq4fUbG" role="3clF46">
-        <property role="TrG5h" value="predicateSymbol" />
-        <node concept="3uibUv" id="2UGjFq4fUbH" role="1tU5fm">
-          <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="2UGjFq4fUbI" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="2UGjFq4fUbJ" role="1tU5fm">
-          <node concept="3uibUv" id="2UGjFq4fUbK" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-      <node concept="3uibUv" id="2UGjFq4gVon" role="3clF45">
-        <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
-      </node>
-      <node concept="3Tm1VV" id="2UGjFq4fUbM" role="1B3o_S" />
-      <node concept="3clFbS" id="2UGjFq4fUbP" role="3clF47">
-        <node concept="3clFbJ" id="2UGjFq4gCHh" role="3cqZAp">
-          <node concept="3clFbS" id="2UGjFq4gCHi" role="3clFbx">
-            <node concept="YS8fn" id="2UGjFq4gCHj" role="3cqZAp">
-              <node concept="2ShNRf" id="2UGjFq4gCHk" role="YScLw">
-                <node concept="1pGfFk" id="2UGjFq4gCHl" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3fqX7Q" id="2UGjFq4gCHm" role="3clFbw">
-            <node concept="1eOMI4" id="2UGjFq4gCHn" role="3fr31v">
-              <node concept="3clFbC" id="2UGjFq4gCHo" role="1eOMHV">
-                <node concept="37vLTw" id="2UGjFq4gCHp" role="3uHU7w">
-                  <ref role="3cqZAo" node="2UGjFq4fUbG" resolve="predicateSymbol" />
-                </node>
-                <node concept="10M0yZ" id="2UGjFq4gCHq" role="3uHU7B">
-                  <ref role="1PxDUh" to="cxk7:3HJTsBn4kk_" resolve="EqualsPredicate" />
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C23RV" resolve="EQ_SYM" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbJ" id="2UGjFq4gGzn" role="3cqZAp">
-          <node concept="3clFbS" id="2UGjFq4gGzp" role="3clFbx">
-            <node concept="YS8fn" id="2UGjFq4gGKH" role="3cqZAp">
-              <node concept="2ShNRf" id="2UGjFq4gGKI" role="YScLw">
-                <node concept="1pGfFk" id="2UGjFq4gGKJ" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3y3z36" id="2UGjFq4gGId" role="3clFbw">
-            <node concept="2OqwBi" id="2UGjFq4gGA0" role="3uHU7B">
-              <node concept="37vLTw" id="2UGjFq4gG$_" role="2Oq$k0">
-                <ref role="3cqZAo" node="2UGjFq4fUbI" resolve="args" />
-              </node>
-              <node concept="1Rwk04" id="2UGjFq4gGD3" role="2OqNvi" />
-            </node>
-            <node concept="3cmrfG" id="2UGjFq4gGKt" role="3uHU7w">
-              <property role="3cmrfH" value="2" />
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbH" id="2UGjFq4gGy9" role="3cqZAp" />
-        <node concept="3clFbF" id="2UGjFq4gGf7" role="3cqZAp">
-          <node concept="2ShNRf" id="2UGjFq4gGf3" role="3clFbG">
-            <node concept="1pGfFk" id="2UGjFq4gGqL" role="2ShVmc">
-              <ref role="37wK5l" to="cxk7:4xBopTzo_Q1" resolve="EqualsPredicate" />
-              <node concept="AH0OO" id="2UGjFq4gGMM" role="37wK5m">
-                <node concept="3cmrfG" id="2UGjFq4gGPb" role="AHEQo">
-                  <property role="3cmrfH" value="0" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4gGLk" role="AHHXb">
-                  <ref role="3cqZAo" node="2UGjFq4fUbI" resolve="args" />
-                </node>
-              </node>
-              <node concept="AH0OO" id="2UGjFq4gGVM" role="37wK5m">
-                <node concept="3cmrfG" id="2UGjFq4gGWG" role="AHEQo">
-                  <property role="3cmrfH" value="1" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4gGTN" role="AHHXb">
-                  <ref role="3cqZAo" node="2UGjFq4fUbI" resolve="args" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="2UGjFq4gVHK" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
     <node concept="2tJIrI" id="2UGjFq4fUQ7" role="jymVt" />
     <node concept="3clFb_" id="2UGjFq4lDR5" role="jymVt">
       <property role="1EzhhJ" value="false" />
@@ -1625,8 +1524,8 @@
       </node>
     </node>
     <node concept="3Tm1VV" id="3HJTsBn4oh0" role="1B3o_S" />
-    <node concept="3uibUv" id="6H279bUP8wy" role="EKbjA">
-      <ref role="3uigEE" to="w7la:~Solver" resolve="Solver" />
+    <node concept="3uibUv" id="5jCHAT2K9kD" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
     </node>
   </node>
   <node concept="312cEu" id="4xBopTzrd8Y">
@@ -1942,8 +1841,8 @@
     </node>
     <node concept="2tJIrI" id="7ISVfSIZY1" role="jymVt" />
     <node concept="3Tm1VV" id="4xBopTzrd8Z" role="1B3o_S" />
-    <node concept="3uibUv" id="6H279bUPewp" role="EKbjA">
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@@ -1970,81 +1869,11 @@
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@@ -2101,236 +1930,17 @@
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@@ -2341,99 +1951,6 @@
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-      <node concept="3Tm1VV" id="2UGjFq4gIzi" role="1B3o_S" />
-      <node concept="3clFbS" id="2UGjFq4gIzl" role="3clF47">
-        <node concept="3clFbJ" id="2UGjFq4gINO" role="3cqZAp">
-          <node concept="3clFbS" id="2UGjFq4gINQ" role="3clFbx">
-            <node concept="YS8fn" id="2UGjFq4gJfn" role="3cqZAp">
-              <node concept="2ShNRf" id="2UGjFq4gJfT" role="YScLw">
-                <node concept="1pGfFk" id="2UGjFq4gJrj" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3fqX7Q" id="2UGjFq4gJ50" role="3clFbw">
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-                <node concept="37vLTw" id="2UGjFq4gJbM" role="3uHU7w">
-                  <ref role="3cqZAo" node="2UGjFq4gIzc" resolve="predicateSymbol" />
-                </node>
-                <node concept="10M0yZ" id="2UGjFq4gJ6t" role="3uHU7B">
-                  <ref role="1PxDUh" to="cxk7:6infEALAfer" resolve="AssertPredicate" />
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7BZnLB" resolve="ASSERT_SYM" />
-                </node>
-              </node>
-            </node>
-          </node>
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-                <node concept="1pGfFk" id="2UGjFq4gIJ4" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;(java.lang.String)" resolve="IllegalArgumentException" />
-                  <node concept="Xl_RD" id="2UGjFq4gIJ5" role="37wK5m">
-                    <property role="Xl_RC" value="invalid arguments count" />
-                  </node>
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3y3z36" id="2UGjFq4gIJ6" role="3clFbw">
-            <node concept="3cmrfG" id="2UGjFq4gIJ7" role="3uHU7w">
-              <property role="3cmrfH" value="1" />
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-            <node concept="2OqwBi" id="2UGjFq4gIJ8" role="3uHU7B">
-              <node concept="37vLTw" id="2UGjFq4gJsn" role="2Oq$k0">
-                <ref role="3cqZAo" node="2UGjFq4gIze" resolve="args" />
-              </node>
-              <node concept="1Rwk04" id="2UGjFq4gIJa" role="2OqNvi" />
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbH" id="2UGjFq4gIMC" role="3cqZAp" />
-        <node concept="3clFbF" id="2UGjFq4gJwr" role="3cqZAp">
-          <node concept="2ShNRf" id="2UGjFq4gJwn" role="3clFbG">
-            <node concept="1pGfFk" id="2UGjFq4gJGs" role="2ShVmc">
-              <ref role="37wK5l" to="cxk7:4xBopTzrPWl" resolve="AssertPredicate" />
-              <node concept="AH0OO" id="2UGjFq4gJI2" role="37wK5m">
-                <node concept="3cmrfG" id="2UGjFq4gJJ6" role="AHEQo">
-                  <property role="3cmrfH" value="0" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4gJGY" role="AHHXb">
-                  <ref role="3cqZAo" node="2UGjFq4gIze" resolve="args" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="2UGjFq4gV8R" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
     <node concept="2tJIrI" id="2UGjFq4gIew" role="jymVt" />
     <node concept="3clFb_" id="2UGjFq4l$TY" role="jymVt">
       <property role="1EzhhJ" value="false" />
@@ -2681,9 +2198,6 @@
     </node>
     <node concept="2tJIrI" id="4xBopTzrRzV" role="jymVt" />
     <node concept="3Tm1VV" id="6infEALAKBH" role="1B3o_S" />
-    <node concept="3uibUv" id="6H279bUPaLB" role="EKbjA">
-      <ref role="3uigEE" to="w7la:~Solver" resolve="Solver" />
-    </node>
     <node concept="3clFb_" id="6infEALAKQz" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="_tellAssert" />
@@ -2917,13 +2431,13 @@
       </node>
     </node>
     <node concept="2tJIrI" id="6infEALAT0A" role="jymVt" />
+    <node concept="3uibUv" id="5jCHAT2K83b" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
+    </node>
   </node>
   <node concept="312cEu" id="6GYQG_Spvw5">
     <property role="TrG5h" value="UnificationSolver" />
     <node concept="3Tm1VV" id="6GYQG_Spvw6" role="1B3o_S" />
-    <node concept="3uibUv" id="6H279bUP3zp" role="EKbjA">
-      <ref role="3uigEE" to="w7la:~Solver" resolve="Solver" />
-    </node>
     <node concept="2tJIrI" id="4U_yxogBZmE" role="jymVt" />
     <node concept="3clFbW" id="5p8T3QHGKJ7" role="jymVt">
       <node concept="3cqZAl" id="5p8T3QHGKJ8" role="3clF45" />
@@ -2950,101 +2464,6 @@
         </node>
       </node>
     </node>
-    <node concept="2tJIrI" id="6MYr6Jw_jvR" role="jymVt" />
-    <node concept="3clFb_" id="2UGjFq4h7S4" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="predicate" />
-      <node concept="37vLTG" id="2UGjFq4h7S5" role="3clF46">
-        <property role="TrG5h" value="predicateSymbol" />
-        <node concept="3uibUv" id="2UGjFq4h7S6" role="1tU5fm">
-          <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="2UGjFq4h7S7" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="2UGjFq4h7S8" role="1tU5fm">
-          <node concept="3uibUv" id="2UGjFq4h7S9" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-      <node concept="3uibUv" id="2UGjFq4h7Sa" role="3clF45">
-        <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
-      </node>
-      <node concept="3Tm1VV" id="2UGjFq4h7Sb" role="1B3o_S" />
-      <node concept="3clFbS" id="2UGjFq4h7Se" role="3clF47">
-        <node concept="3clFbJ" id="2UGjFq4ha4u" role="3cqZAp">
-          <node concept="3clFbS" id="2UGjFq4ha4v" role="3clFbx">
-            <node concept="YS8fn" id="2UGjFq4haib" role="3cqZAp">
-              <node concept="2ShNRf" id="2UGjFq4hajb" role="YScLw">
-                <node concept="1pGfFk" id="2UGjFq4hau_" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3fqX7Q" id="2UGjFq4ha5w" role="3clFbw">
-            <node concept="1eOMI4" id="2UGjFq4ha5y" role="3fr31v">
-              <node concept="3clFbC" id="2UGjFq4hacB" role="1eOMHV">
-                <node concept="10M0yZ" id="2UGjFq4haeG" role="3uHU7w">
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4ha8n" role="3uHU7B">
-                  <ref role="3cqZAo" node="2UGjFq4h7S5" resolve="predicateSymbol" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbJ" id="2UGjFq4hbEc" role="3cqZAp">
-          <node concept="3clFbS" id="2UGjFq4hbEd" role="3clFbx">
-            <node concept="YS8fn" id="2UGjFq4hbEe" role="3cqZAp">
-              <node concept="2ShNRf" id="2UGjFq4hbEf" role="YScLw">
-                <node concept="1pGfFk" id="2UGjFq4hbEg" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3y3z36" id="2UGjFq4hbEh" role="3clFbw">
-            <node concept="2OqwBi" id="2UGjFq4hbEi" role="3uHU7B">
-              <node concept="37vLTw" id="2UGjFq4hbEj" role="2Oq$k0">
-                <ref role="3cqZAo" node="2UGjFq4h7S7" resolve="args" />
-              </node>
-              <node concept="1Rwk04" id="2UGjFq4hbEk" role="2OqNvi" />
-            </node>
-            <node concept="3cmrfG" id="2UGjFq4hbEl" role="3uHU7w">
-              <property role="3cmrfH" value="2" />
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbH" id="2UGjFq4hauR" role="3cqZAp" />
-        <node concept="3clFbF" id="2UGjFq4haww" role="3cqZAp">
-          <node concept="2ShNRf" id="2UGjFq4haws" role="3clFbG">
-            <node concept="1pGfFk" id="2UGjFq4haG0" role="2ShVmc">
-              <ref role="37wK5l" to="cxk7:4xBopTzmopz" resolve="UnificationPredicate" />
-              <node concept="AH0OO" id="2UGjFq4haIN" role="37wK5m">
-                <node concept="3cmrfG" id="2UGjFq4haKu" role="AHEQo">
-                  <property role="3cmrfH" value="0" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4haH8" role="AHHXb">
-                  <ref role="3cqZAo" node="2UGjFq4h7S7" resolve="args" />
-                </node>
-              </node>
-              <node concept="AH0OO" id="2UGjFq4haPn" role="37wK5m">
-                <node concept="3cmrfG" id="2UGjFq4haQn" role="AHEQo">
-                  <property role="3cmrfH" value="1" />
-                </node>
-                <node concept="37vLTw" id="2UGjFq4haN9" role="AHHXb">
-                  <ref role="3cqZAo" node="2UGjFq4h7S7" resolve="args" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-    </node>
     <node concept="2tJIrI" id="2UGjFq4h8Y6" role="jymVt" />
     <node concept="3clFb_" id="2UGjFq4m5q0" role="jymVt">
       <property role="1EzhhJ" value="false" />
@@ -5166,6 +4585,9 @@
       </node>
     </node>
     <node concept="2tJIrI" id="6MYr6JwBO6F" role="jymVt" />
+    <node concept="3uibUv" id="5jCHAT2KfAu" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
+    </node>
   </node>
   <node concept="312cEu" id="4psy6tqstt4">
     <property role="TrG5h" value="NoSolver" />
@@ -5219,44 +4641,9 @@
         <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
       </node>
     </node>
-    <node concept="2tJIrI" id="4psy6tqsuX1" role="jymVt" />
-    <node concept="3clFb_" id="4psy6tqstD0" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="predicate" />
-      <node concept="37vLTG" id="4psy6tqstD1" role="3clF46">
-        <property role="TrG5h" value="predicateSymbol" />
-        <node concept="3uibUv" id="4psy6tqstD2" role="1tU5fm">
-          <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="4psy6tqstD3" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="4psy6tqstD4" role="1tU5fm">
-          <node concept="3uibUv" id="4psy6tqstD5" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-      <node concept="3uibUv" id="4psy6tqstD6" role="3clF45">
-        <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
-      </node>
-      <node concept="3Tm1VV" id="4psy6tqstD7" role="1B3o_S" />
-      <node concept="3clFbS" id="4psy6tqstDc" role="3clF47">
-        <node concept="YS8fn" id="4psy6tqswOD" role="3cqZAp">
-          <node concept="2ShNRf" id="4psy6tqswOE" role="YScLw">
-            <node concept="1pGfFk" id="4psy6tqswOF" role="2ShVmc">
-              <ref role="37wK5l" to="wyt6:~UnsupportedOperationException.&lt;init&gt;()" resolve="UnsupportedOperationException" />
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="4psy6tqstDd" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
     <node concept="3Tm1VV" id="4psy6tqstt5" role="1B3o_S" />
-    <node concept="3uibUv" id="4psy6tqstwo" role="EKbjA">
-      <ref role="3uigEE" to="w7la:~Solver" resolve="Solver" />
+    <node concept="3uibUv" id="5jCHAT2KbNm" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
     </node>
   </node>
   <node concept="312cEu" id="7rf49Nglh1q">
@@ -5264,9 +4651,9 @@
     <node concept="2tJIrI" id="7rf49NgligE" role="jymVt" />
     <node concept="3clFbW" id="7rf49Nglkbs" role="jymVt">
       <node concept="37vLTG" id="7rf49Nglkc0" role="3clF46">
-        <property role="TrG5h" value="sessionQueryable" />
-        <node concept="3uibUv" id="5jCHAT1J4T_" role="1tU5fm">
-          <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+        <property role="TrG5h" value="sessionSolver" />
+        <node concept="3uibUv" id="5jCHAT2LqST" role="1tU5fm">
+          <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
         </node>
       </node>
       <node concept="3cqZAl" id="7rf49Nglkbu" role="3clF45" />
@@ -5277,114 +4664,90 @@
             <node concept="2OqwBi" id="7rf49Nglkk7" role="37vLTJ">
               <node concept="Xjq3P" id="7rf49NglkkE" role="2Oq$k0" />
               <node concept="2OwXpG" id="7rf49Nglkka" role="2OqNvi">
-                <ref role="2Oxat5" node="7rf49Nglke4" resolve="sessionQueryable" />
+                <ref role="2Oxat5" node="7rf49Nglke4" resolve="sessionSolver" />
               </node>
             </node>
             <node concept="37vLTw" id="7rf49Nglkee" role="37vLTx">
-              <ref role="3cqZAo" node="7rf49Nglkc0" resolve="sessionQueryable" />
+              <ref role="3cqZAo" node="7rf49Nglkc0" resolve="sessionSolver" />
             </node>
           </node>
         </node>
       </node>
     </node>
-    <node concept="2tJIrI" id="7rf49NgligJ" role="jymVt" />
-    <node concept="3clFb_" id="7rf49Nglkzf" role="jymVt">
+    <node concept="2tJIrI" id="5jCHAT2E$P8" role="jymVt" />
+    <node concept="3clFb_" id="5jCHAT2VOX7" role="jymVt">
       <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="predicate" />
+      <property role="TrG5h" value="invocationArguments" />
       <property role="DiZV1" value="false" />
       <property role="od$2w" value="false" />
-      <node concept="3Tm1VV" id="7rf49Nglkzg" role="1B3o_S" />
-      <node concept="3uibUv" id="7rf49Nglkzi" role="3clF45">
-        <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
+      <node concept="3Tmbuc" id="5jCHAT2VOX8" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2VOX9" role="3clF45">
+        <ref role="3uigEE" to="33ny:~List" resolve="List" />
+        <node concept="3qTvmN" id="5jCHAT2VOXa" role="11_B2D" />
       </node>
-      <node concept="37vLTG" id="7rf49Nglkzj" role="3clF46">
-        <property role="TrG5h" value="symbol" />
-        <node concept="3uibUv" id="7rf49Nglkzk" role="1tU5fm">
-          <ref role="3uigEE" to="av0y:~PredicateSymbol" resolve="PredicateSymbol" />
+      <node concept="37vLTG" id="5jCHAT2VOXb" role="3clF46">
+        <property role="TrG5h" value="predicate" />
+        <node concept="3uibUv" id="5jCHAT2VOXc" role="1tU5fm">
+          <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
         </node>
       </node>
-      <node concept="37vLTG" id="7rf49Nglkzl" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="7rf49Nglkzm" role="1tU5fm">
-          <node concept="3uibUv" id="7rf49Nglkzn" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
+      <node concept="37vLTG" id="5jCHAT2VOXd" role="3clF46">
+        <property role="TrG5h" value="logicalContext" />
+        <node concept="3uibUv" id="5jCHAT2VOXe" role="1tU5fm">
+          <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
         </node>
       </node>
-      <node concept="3clFbS" id="7rf49Nglkzr" role="3clF47">
-        <node concept="3clFbJ" id="7rf49NgllrT" role="3cqZAp">
-          <node concept="3clFbS" id="7rf49NgllrV" role="3clFbx">
-            <node concept="YS8fn" id="7rf49NgllKg" role="3cqZAp">
-              <node concept="2ShNRf" id="7rf49NgllLk" role="YScLw">
-                <node concept="1pGfFk" id="7rf49NgllXi" role="2ShVmc">
-                  <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;()" resolve="IllegalArgumentException" />
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-              </node>
-            </node>
-          </node>
-          <node concept="3fqX7Q" id="7rf49NgllsX" role="3clFbw">
-            <node concept="1eOMI4" id="7rf49NgllsZ" role="3fr31v">
-              <node concept="3clFbC" id="7rf49Ngll_u" role="1eOMHV">
-                <node concept="37vLTw" id="7rf49NgllBl" role="3uHU7w">
-                  <ref role="3cqZAo" node="7rf49Nglkzj" resolve="symbol" />
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-                <node concept="10M0yZ" id="7rf49NglluE" role="3uHU7B">
-                  <ref role="1PxDUh" to="cxk7:7rf49NgkbDQ" resolve="NotPredicate" />
-                  <ref role="3cqZAo" to="cxk7:7rf49Ngke3n" resolve="NOT_SYM" />
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-        <node concept="3clFbJ" id="7rf49Nglm1J" role="3cqZAp">
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-          <node concept="3y3z36" id="7rf49Nglo3G" role="3clFbw">
-            <node concept="2OqwBi" id="7rf49NglnbY" role="3uHU7B">
-              <node concept="37vLTw" id="7rf49NglmYG" role="2Oq$k0">
-                <ref role="3cqZAo" node="7rf49Nglkzl" resolve="args" />
-              </node>
-              <node concept="1Rwk04" id="7rf49NglnyE" role="2OqNvi" />
-            </node>
-            <node concept="3cmrfG" id="7rf49Nglod1" role="3uHU7w">
-              <property role="3cmrfH" value="1" />
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbH" id="7rf49Nglp4b" role="3cqZAp" />
-        <node concept="3clFbF" id="7rf49Nglq3J" role="3cqZAp">
-          <node concept="2ShNRf" id="7rf49Nglq3F" role="3clFbG">
-            <node concept="1pGfFk" id="7rf49Nglqhj" role="2ShVmc">
-              <ref role="37wK5l" to="cxk7:7rf49NgkbFA" resolve="NotPredicate" />
-              <node concept="10QFUN" id="7rf49Ngls61" role="37wK5m">
-                <node concept="3uibUv" id="7rf49Ngls5X" role="10QFUM">
-                  <ref role="3uigEE" to="av0y:~Predicate" resolve="Predicate" />
-                </node>
-                <node concept="AH0OO" id="7rf49Ngls5Y" role="10QFUP">
-                  <node concept="3cmrfG" id="7rf49Ngls5Z" role="AHEQo">
-                    <property role="3cmrfH" value="0" />
-                  </node>
-                  <node concept="37vLTw" id="7rf49Ngls60" role="AHHXb">
-                    <ref role="3cqZAo" node="7rf49Nglkzl" resolve="args" />
-                  </node>
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="7rf49Nglkzs" role="2AJF6D">
+      <node concept="2AHcQZ" id="5jCHAT2VOYc" role="2AJF6D">
         <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
       </node>
+      <node concept="3clFbS" id="5jCHAT2VOYd" role="3clF47">
+        <node concept="3cpWs8" id="7rf49NglQh2" role="3cqZAp">
+          <node concept="3cpWsn" id="7rf49NglQh3" role="3cpWs9">
+            <property role="TrG5h" value="paramPredicate" />
+            <node concept="3uibUv" id="7rf49NglX99" role="1tU5fm">
+              <ref role="3uigEE" to="cxk7:6Kcfpq7B0Wu" resolve="AbstractPredicate" />
+            </node>
+            <node concept="10QFUN" id="7rf49NglQh4" role="33vP2m">
+              <node concept="3uibUv" id="7rf49NglXvv" role="10QFUM">
+                <ref role="3uigEE" to="cxk7:6Kcfpq7B0Wu" resolve="AbstractPredicate" />
+              </node>
+              <node concept="2OqwBi" id="7rf49NglQh6" role="10QFUP">
+                <node concept="2OqwBi" id="5jCHAT2VQif" role="2Oq$k0">
+                  <node concept="37vLTw" id="5jCHAT2VQmr" role="2Oq$k0">
+                    <ref role="3cqZAo" node="5jCHAT2VOXb" resolve="predicate" />
+                  </node>
+                  <node concept="liA8E" id="5jCHAT2VQii" role="2OqNvi">
+                    <ref role="37wK5l" to="av0y:~AndItem.arguments():java.util.List" resolve="arguments" />
+                  </node>
+                </node>
+                <node concept="liA8E" id="7rf49NglQh8" role="2OqNvi">
+                  <ref role="37wK5l" to="33ny:~List.get(int):java.lang.Object" resolve="get" />
+                  <node concept="3cmrfG" id="7rf49NglQh9" role="37wK5m">
+                    <property role="3cmrfH" value="0" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="5jCHAT2VR8v" role="3cqZAp">
+          <node concept="2YIFZM" id="5jCHAT2VR8w" role="3clFbG">
+            <ref role="1Pybhc" to="33ny:~Collections" resolve="Collections" />
+            <ref role="37wK5l" to="33ny:~Collections.singletonList(java.lang.Object):java.util.List" resolve="singletonList" />
+            <node concept="1rXfSq" id="5jCHAT2VREB" role="37wK5m">
+              <ref role="37wK5l" to="w7la:~AbstractSolver.invocation(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):jetbrains.mps.logic.reactor.evaluation.PredicateInvocation" resolve="invocation" />
+              <node concept="37vLTw" id="5jCHAT2VRUG" role="37wK5m">
+                <ref role="3cqZAo" node="7rf49NglQh3" resolve="paramPredicate" />
+              </node>
+              <node concept="37vLTw" id="5jCHAT2VSa3" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT2VOXd" resolve="logicalContext" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
     </node>
-    <node concept="2tJIrI" id="7rf49NglklY" role="jymVt" />
+    <node concept="2tJIrI" id="5jCHAT2VPhG" role="jymVt" />
     <node concept="3clFb_" id="7rf49Nglkz3" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="ask" />
@@ -5434,10 +4797,10 @@
             <node concept="1eOMI4" id="7rf49Nglzkw" role="3fr31v">
               <node concept="2OqwBi" id="7rf49Nglzkx" role="1eOMHV">
                 <node concept="37vLTw" id="7rf49Nglzky" role="2Oq$k0">
-                  <ref role="3cqZAo" node="7rf49Nglke4" resolve="sessionQueryable" />
+                  <ref role="3cqZAo" node="7rf49Nglke4" resolve="sessionSolver" />
                 </node>
                 <node concept="liA8E" id="7rf49Nglzkz" role="2OqNvi">
-                  <ref role="37wK5l" to="w7la:~Queryable.ask(jetbrains.mps.logic.reactor.evaluation.PredicateInvocation):boolean" resolve="ask" />
+                  <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.evaluation.PredicateInvocation):boolean" resolve="ask" />
                   <node concept="37vLTw" id="7rf49Nglzk$" role="37wK5m">
                     <ref role="3cqZAo" node="7rf49Nglx98" resolve="predInv" />
                   </node>
@@ -5481,15 +4844,15 @@
     <node concept="2tJIrI" id="7rf49Nglkmj" role="jymVt" />
     <node concept="3Tm1VV" id="7rf49Nglh1r" role="1B3o_S" />
     <node concept="312cEg" id="7rf49Nglke4" role="jymVt">
-      <property role="TrG5h" value="sessionQueryable" />
+      <property role="TrG5h" value="sessionSolver" />
       <node concept="3Tm6S6" id="7rf49Nglke5" role="1B3o_S" />
-      <node concept="3uibUv" id="5jCHAT1J5mQ" role="1tU5fm">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2Lr1Y" role="1tU5fm">
+        <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
       </node>
     </node>
     <node concept="2tJIrI" id="5jCHAT1JF$c" role="jymVt" />
-    <node concept="3uibUv" id="7rf49Nglkq3" role="EKbjA">
-      <ref role="3uigEE" to="w7la:~Solver" resolve="Solver" />
+    <node concept="3uibUv" id="5jCHAT2KbZm" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
     </node>
   </node>
 </model>
diff --git a/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification.mps b/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification.mps
index f75be8b6..149439f9 100644
--- a/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification.mps
+++ b/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification.mps
@@ -236,43 +236,6 @@
         </node>
       </node>
     </node>
-    <node concept="2tJIrI" id="2tcGHBEzo4L" role="jymVt" />
-    <node concept="3clFb_" id="5jCHAT1MMTj" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="sessionInstructible" />
-      <property role="DiZV1" value="false" />
-      <property role="od$2w" value="false" />
-      <node concept="3Tm1VV" id="5jCHAT1MMTk" role="1B3o_S" />
-      <node concept="3uibUv" id="5jCHAT1MMTm" role="3clF45">
-        <ref role="3uigEE" to="w7la:~Instructible" resolve="Instructible" />
-      </node>
-      <node concept="3clFbS" id="5jCHAT1MMTn" role="3clF47">
-        <node concept="3clFbF" id="5jCHAT1MMTq" role="3cqZAp">
-          <node concept="10Nm6u" id="5jCHAT1MMTp" role="3clFbG" />
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="5jCHAT1MMTo" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
-    <node concept="3clFb_" id="5jCHAT1MMTr" role="jymVt">
-      <property role="1EzhhJ" value="false" />
-      <property role="TrG5h" value="sessionQueryable" />
-      <property role="DiZV1" value="false" />
-      <property role="od$2w" value="false" />
-      <node concept="3Tm1VV" id="5jCHAT1MMTs" role="1B3o_S" />
-      <node concept="3uibUv" id="5jCHAT1MMTu" role="3clF45">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
-      </node>
-      <node concept="3clFbS" id="5jCHAT1MMTv" role="3clF47">
-        <node concept="3clFbF" id="5jCHAT1MMTy" role="3cqZAp">
-          <node concept="10Nm6u" id="5jCHAT1MMTx" role="3clFbG" />
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="5jCHAT1MMTw" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
     <node concept="3clFb_" id="5jCHAT1MMTz" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="storeView" />
diff --git a/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification@tests.mps b/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification@tests.mps
index 9db63b14..1b5e1adf 100644
--- a/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification@tests.mps
+++ b/logic/solutions/jetbrains.mps.logic.test/models/jetbrains/mps/logic/test/unification@tests.mps
@@ -30,6 +30,12 @@
       </concept>
       <concept id="1202948039474" name="jetbrains.mps.baseLanguage.structure.InstanceMethodCallOperation" flags="nn" index="liA8E" />
       <concept id="1465982738277781862" name="jetbrains.mps.baseLanguage.structure.PlaceholderMember" flags="ng" index="2tJIrI" />
+      <concept id="1188207840427" name="jetbrains.mps.baseLanguage.structure.AnnotationInstance" flags="nn" index="2AHcQZ">
+        <reference id="1188208074048" name="annotation" index="2AI5Lk" />
+      </concept>
+      <concept id="1188208481402" name="jetbrains.mps.baseLanguage.structure.HasAnnotation" flags="ng" index="2AJDlI">
+        <child id="1188208488637" name="annotation" index="2AJF6D" />
+      </concept>
       <concept id="2820489544401957797" name="jetbrains.mps.baseLanguage.structure.DefaultClassCreator" flags="nn" index="HV5vD">
         <reference id="2820489544401957798" name="classifier" index="HV5vE" />
       </concept>
@@ -46,9 +52,15 @@
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
+      <concept id="1182160077978" name="jetbrains.mps.baseLanguage.structure.AnonymousClassCreator" flags="nn" index="YeOm9">
+        <child id="1182160096073" name="cls" index="YeSDq" />
+      </concept>
       <concept id="1081236700937" name="jetbrains.mps.baseLanguage.structure.StaticMethodCall" flags="nn" index="2YIFZM">
         <reference id="1144433194310" name="classConcept" index="1Pybhc" />
       </concept>
+      <concept id="1164991038168" name="jetbrains.mps.baseLanguage.structure.ThrowStatement" flags="nn" index="YS8fn">
+        <child id="1164991057263" name="throwable" index="YScLw" />
+      </concept>
       <concept id="1070533707846" name="jetbrains.mps.baseLanguage.structure.StaticFieldReference" flags="nn" index="10M0yZ">
         <reference id="1144433057691" name="classifier" index="1PxDUh" />
       </concept>
@@ -61,6 +73,13 @@
       <concept id="1068431474542" name="jetbrains.mps.baseLanguage.structure.VariableDeclaration" flags="ng" index="33uBYm">
         <child id="1068431790190" name="initializer" index="33vP2m" />
       </concept>
+      <concept id="1109279763828" name="jetbrains.mps.baseLanguage.structure.TypeVariableDeclaration" flags="ng" index="16euLQ" />
+      <concept id="1109279851642" name="jetbrains.mps.baseLanguage.structure.GenericDeclaration" flags="ng" index="16eOlS">
+        <child id="1109279881614" name="typeVariableDeclaration" index="16eVyc" />
+      </concept>
+      <concept id="1109283449304" name="jetbrains.mps.baseLanguage.structure.TypeVariableReference" flags="in" index="16syzq">
+        <reference id="1109283546497" name="typeVariableDeclaration" index="16sUi3" />
+      </concept>
       <concept id="1068498886296" name="jetbrains.mps.baseLanguage.structure.VariableReference" flags="nn" index="37vLTw">
         <reference id="1068581517664" name="variableDeclaration" index="3cqZAo" />
       </concept>
@@ -71,11 +90,15 @@
         <child id="5680397130376446158" name="type" index="1tU5fm" />
       </concept>
       <concept id="1068580123132" name="jetbrains.mps.baseLanguage.structure.BaseMethodDeclaration" flags="ng" index="3clF44">
+        <property id="4276006055363816570" name="isSynchronized" index="od$2w" />
+        <property id="1181808852946" name="isFinal" index="DiZV1" />
         <child id="1068580123133" name="returnType" index="3clF45" />
         <child id="1068580123134" name="parameter" index="3clF46" />
         <child id="1068580123135" name="body" index="3clF47" />
       </concept>
-      <concept id="1068580123165" name="jetbrains.mps.baseLanguage.structure.InstanceMethodDeclaration" flags="ig" index="3clFb_" />
+      <concept id="1068580123165" name="jetbrains.mps.baseLanguage.structure.InstanceMethodDeclaration" flags="ig" index="3clFb_">
+        <property id="1178608670077" name="isAbstract" index="1EzhhJ" />
+      </concept>
       <concept id="1068580123152" name="jetbrains.mps.baseLanguage.structure.EqualsExpression" flags="nn" index="3clFbC" />
       <concept id="1068580123155" name="jetbrains.mps.baseLanguage.structure.ExpressionStatement" flags="nn" index="3clFbF">
         <child id="1068580123156" name="expression" index="3clFbG" />
@@ -103,6 +126,7 @@
         <child id="1212687122400" name="typeParameter" index="1pMfVU" />
       </concept>
       <concept id="1107461130800" name="jetbrains.mps.baseLanguage.structure.Classifier" flags="ng" index="3pOWGL">
+        <property id="521412098689998745" name="nonStatic" index="2bfB8j" />
         <child id="5375687026011219971" name="member" index="jymVt" unordered="true" />
       </concept>
       <concept id="1171903607971" name="jetbrains.mps.baseLanguage.structure.WildCardType" flags="in" index="3qTvmN" />
@@ -132,6 +156,9 @@
       <concept id="1116615150612" name="jetbrains.mps.baseLanguage.structure.ClassifierClassExpression" flags="nn" index="3VsKOn">
         <reference id="1116615189566" name="classifier" index="3VsUkX" />
       </concept>
+      <concept id="1170345865475" name="jetbrains.mps.baseLanguage.structure.AnonymousClass" flags="ig" index="1Y3b0j">
+        <reference id="1170346070688" name="classifier" index="1Y3XeK" />
+      </concept>
     </language>
     <language id="f61473f9-130f-42f6-b98d-6c438812c2f6" name="jetbrains.mps.baseLanguage.unitTest">
       <concept id="7080278351417106679" name="jetbrains.mps.baseLanguage.unitTest.structure.AssertInNotNull" flags="nn" index="2Hmddi">
@@ -1649,6 +1676,63 @@
   <node concept="3s_ewN" id="1OShD0IfsNp">
     <property role="3s_ewP" value="TellUniSolver" />
     <node concept="2tJIrI" id="2tcGHBEipQe" role="jymVt" />
+    <node concept="312cEg" id="5jCHAT2dJM2" role="jymVt">
+      <property role="TrG5h" value="NO_CONTEXT" />
+      <node concept="3Tm6S6" id="5jCHAT2dJM3" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2dKeE" role="1tU5fm">
+        <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
+      </node>
+      <node concept="2ShNRf" id="5jCHAT2dKg0" role="33vP2m">
+        <node concept="YeOm9" id="5jCHAT2dKnF" role="2ShVmc">
+          <node concept="1Y3b0j" id="5jCHAT2dKnI" role="YeSDq">
+            <property role="2bfB8j" value="true" />
+            <ref role="1Y3XeK" to="bj13:~LogicalContext" resolve="LogicalContext" />
+            <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+            <node concept="3Tm1VV" id="5jCHAT2dKnJ" role="1B3o_S" />
+            <node concept="3clFb_" id="5jCHAT2dKnK" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="variable" />
+              <property role="DiZV1" value="false" />
+              <property role="od$2w" value="false" />
+              <node concept="3Tm1VV" id="5jCHAT2dKnL" role="1B3o_S" />
+              <node concept="16euLQ" id="5jCHAT2dKnN" role="16eVyc">
+                <property role="TrG5h" value="V" />
+              </node>
+              <node concept="3uibUv" id="5jCHAT2dKnO" role="3clF45">
+                <ref role="3uigEE" to="bj13:~Logical" resolve="Logical" />
+                <node concept="16syzq" id="5jCHAT2dKnP" role="11_B2D">
+                  <ref role="16sUi3" node="5jCHAT2dKnN" resolve="V" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="5jCHAT2dKnQ" role="3clF46">
+                <property role="TrG5h" value="p0" />
+                <node concept="3uibUv" id="5jCHAT2dKnR" role="1tU5fm">
+                  <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  <node concept="16syzq" id="5jCHAT2dKnS" role="11_B2D">
+                    <ref role="16sUi3" node="5jCHAT2dKnN" resolve="V" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbS" id="5jCHAT2dKnT" role="3clF47">
+                <node concept="YS8fn" id="5jCHAT2dKwo" role="3cqZAp">
+                  <node concept="2ShNRf" id="5jCHAT2dKxx" role="YScLw">
+                    <node concept="1pGfFk" id="5jCHAT2dKLh" role="2ShVmc">
+                      <ref role="37wK5l" to="wyt6:~UnsupportedOperationException.&lt;init&gt;(java.lang.String)" resolve="UnsupportedOperationException" />
+                      <node concept="Xl_RD" id="5jCHAT2dKOW" role="37wK5m">
+                        <property role="Xl_RC" value="not implemented" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="2AHcQZ" id="5jCHAT2dNAi" role="2AJF6D">
+                <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
     <node concept="2tJIrI" id="6yEjedm71gP" role="jymVt" />
     <node concept="3clFb_" id="6yEjedm71gQ" role="jymVt">
       <property role="TrG5h" value="var" />
@@ -1945,16 +2029,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_vsV" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_vv8" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ieX6" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNF6V" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfuGw" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNF9Y" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfuGF" resolve="b" />
+                  </node>
                 </node>
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-                <node concept="37vLTw" id="5jPBdKNF9Y" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfuGF" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ifcu" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2082,16 +2169,19 @@
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               </node>
               <node concept="liA8E" id="5jPBdKNFjn" role="2OqNvi">
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-                <node concept="10M0yZ" id="5jPBdKNFjo" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ieaW" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNFjp" role="37wK5m">
+                    <ref role="3cqZAo" node="3HJTsBn443g" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNFjq" role="37wK5m">
+                    <ref role="3cqZAo" node="3HJTsBn443w" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNFjp" role="37wK5m">
-                  <ref role="3cqZAo" node="3HJTsBn443g" resolve="a" />
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-                <node concept="37vLTw" id="5jPBdKNFjq" role="37wK5m">
-                  <ref role="3cqZAo" node="3HJTsBn443w" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ieoT" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2265,16 +2355,19 @@
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               </node>
               <node concept="liA8E" id="5jPBdKNFBb" role="2OqNvi">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dPkD" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNFBd" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivynhQ" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNFBe" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivy$Me" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNFBd" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivynhQ" resolve="a" />
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-                <node concept="37vLTw" id="5jPBdKNFBe" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivy$Me" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2dPCF" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2292,16 +2385,19 @@
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               </node>
               <node concept="liA8E" id="5jPBdKNFL9" role="2OqNvi">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ie$1" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNFLb" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivynhQ" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNFLc" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivy$Me" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNFLb" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivynhQ" resolve="a" />
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-                <node concept="37vLTw" id="5jPBdKNFLc" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivy$Me" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ieNj" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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             </node>
@@ -2347,16 +2443,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNG7h" role="2OqNvi">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dUml" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNGcw" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivyni3" resolve="c" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNGeg" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivy_$I" resolve="d" />
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                 </node>
-                <node concept="37vLTw" id="5jPBdKNGcw" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivyni3" resolve="c" />
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-                <node concept="37vLTw" id="5jPBdKNGeg" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivy_$I" resolve="d" />
+                <node concept="37vLTw" id="5jCHAT2dUFe" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2536,16 +2635,19 @@
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               <node concept="liA8E" id="5jPBdKNGmj" role="2OqNvi">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ickL" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNGml" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfNC5" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNGmm" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfNCg" resolve="b" />
+                  </node>
                 </node>
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-                <node concept="37vLTw" id="5jPBdKNGmm" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfNCg" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2icyN" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2562,16 +2664,19 @@
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2icG8" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNGCr" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfNCg" resolve="b" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNGEd" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfOZy" resolve="c" />
+                  </node>
                 </node>
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-                <node concept="37vLTw" id="5jPBdKNGEd" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfOZy" resolve="c" />
+                <node concept="37vLTw" id="5jCHAT2icU8" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2649,16 +2754,19 @@
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dQMW" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNGZw" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfO_f" resolve="s" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNH1r" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfOGV" resolve="t" />
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                 </node>
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-                <node concept="37vLTw" id="5jPBdKNH1r" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfOGV" resolve="t" />
+                <node concept="37vLTw" id="5jCHAT2dRaR" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2839,16 +2947,19 @@
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2id2M" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNHH2" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylQZ" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNHIZ" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylRf" resolve="b" />
+                  </node>
                 </node>
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-                <node concept="37vLTw" id="5jPBdKNHIZ" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivylRf" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2idig" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2865,16 +2976,19 @@
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2idr_" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNH9y" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylRf" resolve="b" />
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+                  <node concept="37vLTw" id="5jPBdKNH9z" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylRv" resolve="c" />
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                 </node>
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-                <node concept="37vLTw" id="5jPBdKNH9z" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivylRv" resolve="c" />
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+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -2952,16 +3066,19 @@
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+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dPM_" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNHSH" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylS2" resolve="s" />
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+                  <node concept="37vLTw" id="5jPBdKNHSI" role="37wK5m">
+                    <ref role="3cqZAo" node="4XqG8ivylS9" resolve="t" />
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                 </node>
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@@ -3078,16 +3195,19 @@
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+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNHZF" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfW$y" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNHZG" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfW$L" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNHZF" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfW$y" resolve="a" />
-                </node>
-                <node concept="37vLTw" id="5jPBdKNHZG" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfW$L" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2if$p" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3159,16 +3279,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNI3M" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="5jPBdKNI3N" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dRlv" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNI3O" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfYmM" resolve="s" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNI3P" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IfYmT" resolve="t" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNI3O" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfYmM" resolve="s" />
-                </node>
-                <node concept="37vLTw" id="5jPBdKNI3P" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IfYmT" resolve="t" />
+                <node concept="37vLTw" id="5jCHAT2dRDZ" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3314,16 +3437,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNI6T" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdKNI6U" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ii4w" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNI6V" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IgkRu" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNI6W" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0IgkRM" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNI6V" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IgkRu" resolve="a" />
-                </node>
-                <node concept="37vLTw" id="5jPBdKNI6W" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0IgkRM" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2iijM" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3372,29 +3498,32 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNIc2" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="5jPBdKNIc3" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                </node>
-                <node concept="1oi1Uc" id="5jPBdKNIh_" role="37wK5m">
-                  <node concept="1oi5UN" id="5jPBdKNIhA" role="1oi0x0">
-                    <node concept="1oi5Wm" id="5jPBdKNIhB" role="1ojpOf">
-                      <property role="TrG5h" value="name" />
-                      <node concept="1oi5XN" id="5jPBdKNIhC" role="1oi5zu">
-                        <property role="1oi5yK" value="bar" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dTlx" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="5jPBdKNIh_" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNIhA" role="1oi0x0">
+                      <node concept="1oi5Wm" id="5jPBdKNIhB" role="1ojpOf">
+                        <property role="TrG5h" value="name" />
+                        <node concept="1oi5XN" id="5jPBdKNIhC" role="1oi5zu">
+                          <property role="1oi5yK" value="bar" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                  <node concept="1oi1Uc" id="5jPBdKNIhD" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNIhE" role="1oi0x0">
+                      <node concept="22Ky0T" id="5jPBdKNIhF" role="lGtFl">
+                        <node concept="37vLTw" id="5jPBdKNIhG" role="22Ky0K">
+                          <ref role="3cqZAo" node="1OShD0IgkRH" resolve="x" />
+                        </node>
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="5jPBdKNIhD" role="37wK5m">
-                  <node concept="1oi5UN" id="5jPBdKNIhE" role="1oi0x0">
-                    <node concept="22Ky0T" id="5jPBdKNIhF" role="lGtFl">
-                      <node concept="37vLTw" id="5jPBdKNIhG" role="22Ky0K">
-                        <ref role="3cqZAo" node="1OShD0IgkRH" resolve="x" />
-                      </node>
-                    </node>
-                  </node>
+                <node concept="37vLTw" id="5jCHAT2dTF5" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3412,29 +3541,32 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNInr" role="2OqNvi">
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-                <node concept="10M0yZ" id="5jPBdKNIns" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
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-                <node concept="1oi1Uc" id="5jPBdKNIv1" role="37wK5m">
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-                    <node concept="1oi5Wm" id="5jPBdKNIv3" role="1ojpOf">
-                      <property role="TrG5h" value="name" />
-                      <node concept="1oi5XN" id="5jPBdKNIv4" role="1oi5zu">
-                        <property role="1oi5yK" value="bazz" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dROJ" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="5jPBdKNIv1" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNIv2" role="1oi0x0">
+                      <node concept="1oi5Wm" id="5jPBdKNIv3" role="1ojpOf">
+                        <property role="TrG5h" value="name" />
+                        <node concept="1oi5XN" id="5jPBdKNIv4" role="1oi5zu">
+                          <property role="1oi5yK" value="bazz" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                  <node concept="1oi1Uc" id="5jPBdKNIv5" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNIv6" role="1oi0x0">
+                      <node concept="22Ky0T" id="5jPBdKNIv7" role="lGtFl">
+                        <node concept="37vLTw" id="5jPBdKNIv8" role="22Ky0K">
+                          <ref role="3cqZAo" node="1OShD0IglCA" resolve="y" />
+                        </node>
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="5jPBdKNIv5" role="37wK5m">
-                  <node concept="1oi5UN" id="5jPBdKNIv6" role="1oi0x0">
-                    <node concept="22Ky0T" id="5jPBdKNIv7" role="lGtFl">
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-                        <ref role="3cqZAo" node="1OShD0IglCA" resolve="y" />
-                      </node>
-                    </node>
-                  </node>
+                <node concept="37vLTw" id="5jCHAT2dS9w" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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             </node>
@@ -3575,16 +3707,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNIGc" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdKNIGd" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ihGu" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNIGe" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Ig2i$" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNIGf" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Ig2iS" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNIGe" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Ig2i$" resolve="a" />
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-                <node concept="37vLTw" id="5jPBdKNIGf" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Ig2iS" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ihU_" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3620,39 +3755,42 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNIJP" role="2OqNvi">
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-                <node concept="10M0yZ" id="5jPBdKNIJQ" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                </node>
-                <node concept="1oi1Uc" id="5jPBdKNIPU" role="37wK5m">
-                  <node concept="KCUsM" id="5jPBdKNIPV" role="1oi0x0">
-                    <node concept="1oi5UN" id="5jPBdKNIPW" role="KCVpo">
-                      <node concept="1oi5Wm" id="5jPBdKNIPX" role="1ojpOf">
-                        <property role="TrG5h" value="name" />
-                        <node concept="1oi5XN" id="5jPBdKNIPY" role="1oi5zu">
-                          <property role="1oi5yK" value="bazz" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dTPZ" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="5jPBdKNIPU" role="37wK5m">
+                    <node concept="KCUsM" id="5jPBdKNIPV" role="1oi0x0">
+                      <node concept="1oi5UN" id="5jPBdKNIPW" role="KCVpo">
+                        <node concept="1oi5Wm" id="5jPBdKNIPX" role="1ojpOf">
+                          <property role="TrG5h" value="name" />
+                          <node concept="1oi5XN" id="5jPBdKNIPY" role="1oi5zu">
+                            <property role="1oi5yK" value="bazz" />
+                          </node>
+                        </node>
+                      </node>
+                      <node concept="1oi5UN" id="5jPBdKNIPZ" role="KCVpo">
+                        <node concept="1oi5Wm" id="5jPBdKNIQ0" role="1ojpOf">
+                          <property role="TrG5h" value="name" />
+                          <node concept="1oi5XN" id="5jPBdKNIQ1" role="1oi5zu">
+                            <property role="1oi5yK" value="bazzzz" />
+                          </node>
                         </node>
                       </node>
                     </node>
-                    <node concept="1oi5UN" id="5jPBdKNIPZ" role="KCVpo">
-                      <node concept="1oi5Wm" id="5jPBdKNIQ0" role="1ojpOf">
-                        <property role="TrG5h" value="name" />
-                        <node concept="1oi5XN" id="5jPBdKNIQ1" role="1oi5zu">
-                          <property role="1oi5yK" value="bazzzz" />
+                  </node>
+                  <node concept="1oi1Uc" id="5jPBdKNIQ2" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNIQ3" role="1oi0x0">
+                      <node concept="22Ky0T" id="5jPBdKNIQ4" role="lGtFl">
+                        <node concept="37vLTw" id="5jPBdKNIQ5" role="22Ky0K">
+                          <ref role="3cqZAo" node="1OShD0Ig2iN" resolve="x" />
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-                <node concept="1oi1Uc" id="5jPBdKNIQ2" role="37wK5m">
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-                        <ref role="3cqZAo" node="1OShD0Ig2iN" resolve="x" />
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-                    </node>
-                  </node>
+                <node concept="37vLTw" id="5jCHAT2dUbf" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -3774,16 +3912,19 @@
                 </node>
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               <node concept="liA8E" id="5jPBdKNJ05" role="2OqNvi">
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-                <node concept="10M0yZ" id="5jPBdKNJ06" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2idNg" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNJ07" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Ig9w4" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNJ08" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Ig9wj" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNJ07" role="37wK5m">
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-                <node concept="37vLTw" id="5jPBdKNJ08" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Ig9wj" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ie1f" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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@@ -3819,23 +3960,26 @@
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               <node concept="liA8E" id="5jPBdKNJ3q" role="2OqNvi">
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-                      <node concept="37vLTw" id="5jPBdKNJ9b" role="22Ky0K">
-                        <ref role="3cqZAo" node="1OShD0IgaBV" resolve="x" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dQgM" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
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+                    <node concept="1oi5UN" id="5jPBdKNJ99" role="1oi0x0">
+                      <node concept="22Ky0T" id="5jPBdKNJ9a" role="lGtFl">
+                        <node concept="37vLTw" id="5jPBdKNJ9b" role="22Ky0K">
+                          <ref role="3cqZAo" node="1OShD0IgaBV" resolve="x" />
+                        </node>
                       </node>
                     </node>
                   </node>
                 </node>
+                <node concept="37vLTw" id="5jCHAT2dQCA" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
+                </node>
               </node>
             </node>
           </node>
@@ -3923,16 +4067,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNJfw" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdKNJfx" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2igZ1" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdKNJfy" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Igi9l" resolve="a" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdKNJfz" role="37wK5m">
+                    <ref role="3cqZAo" node="1OShD0Igi9u" resolve="b" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdKNJfy" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Igi9l" resolve="a" />
-                </node>
-                <node concept="37vLTw" id="5jPBdKNJfz" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Igi9u" resolve="b" />
+                <node concept="37vLTw" id="5jCHAT2ihd8" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3968,23 +4115,26 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdKNJiD" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="5jPBdKNJiE" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                </node>
-                <node concept="1oi1Uc" id="5jPBdKNJnX" role="37wK5m">
-                  <node concept="KCUsM" id="5jPBdKNJnY" role="1oi0x0" />
-                </node>
-                <node concept="1oi1Uc" id="5jPBdKNJnZ" role="37wK5m">
-                  <node concept="1oi5UN" id="5jPBdKNJo0" role="1oi0x0">
-                    <node concept="22Ky0T" id="5jPBdKNJo1" role="lGtFl">
-                      <node concept="37vLTw" id="5jPBdKNJo2" role="22Ky0K">
-                        <ref role="3cqZAo" node="1OShD0IgiMd" resolve="x" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dOOl" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="5jPBdKNJnX" role="37wK5m">
+                    <node concept="KCUsM" id="5jPBdKNJnY" role="1oi0x0" />
+                  </node>
+                  <node concept="1oi1Uc" id="5jPBdKNJnZ" role="37wK5m">
+                    <node concept="1oi5UN" id="5jPBdKNJo0" role="1oi0x0">
+                      <node concept="22Ky0T" id="5jPBdKNJo1" role="lGtFl">
+                        <node concept="37vLTw" id="5jPBdKNJo2" role="22Ky0K">
+                          <ref role="3cqZAo" node="1OShD0IgiMd" resolve="x" />
+                        </node>
                       </node>
                     </node>
                   </node>
                 </node>
+                <node concept="37vLTw" id="5jCHAT2dPaT" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
+                </node>
               </node>
             </node>
           </node>
@@ -4095,16 +4245,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8ISnx2" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="4$OyT8ISnx3" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ihls" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="4$OyT8ISnx4" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ISnwf" resolve="list" />
+                  </node>
+                  <node concept="37vLTw" id="4$OyT8ISUn_" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ISEPa" resolve="pattern" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="4$OyT8ISnx4" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ISnwf" resolve="list" />
-                </node>
-                <node concept="37vLTw" id="4$OyT8ISUn_" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ISEPa" resolve="pattern" />
+                <node concept="37vLTw" id="5jCHAT2ihz$" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -4140,20 +4293,23 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8ISnxe" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="4$OyT8ISnxf" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                </node>
-                <node concept="1oi1Uc" id="4$OyT8ISnxg" role="37wK5m">
-                  <node concept="1oi5UN" id="4$OyT8ISnxh" role="1oi0x0">
-                    <node concept="1oi5Wm" id="4$OyT8ITRPO" role="1ojpOf">
-                      <property role="TrG5h" value="foo" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dSkg" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="4$OyT8ISnxg" role="37wK5m">
+                    <node concept="1oi5UN" id="4$OyT8ISnxh" role="1oi0x0">
+                      <node concept="1oi5Wm" id="4$OyT8ITRPO" role="1ojpOf">
+                        <property role="TrG5h" value="foo" />
+                      </node>
                     </node>
                   </node>
+                  <node concept="37vLTw" id="4$OyT8ITJQQ" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ISnwx" resolve="head" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="4$OyT8ITJQQ" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ISnwx" resolve="head" />
+                <node concept="37vLTw" id="5jCHAT2dSEI" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -4171,38 +4327,41 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8ISnxu" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="4$OyT8ISnxv" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
-                </node>
-                <node concept="1oi1Uc" id="4$OyT8ISnxw" role="37wK5m">
-                  <node concept="KCUsM" id="4$OyT8ISWUk" role="1oi0x0">
-                    <node concept="1oi5UN" id="4$OyT8ISXyO" role="KCVpo">
-                      <node concept="1oi5Wm" id="4$OyT8ISXyP" role="1ojpOf">
-                        <property role="TrG5h" value="bar" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dNRn" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="4$OyT8ISnxw" role="37wK5m">
+                    <node concept="KCUsM" id="4$OyT8ISWUk" role="1oi0x0">
+                      <node concept="1oi5UN" id="4$OyT8ISXyO" role="KCVpo">
+                        <node concept="1oi5Wm" id="4$OyT8ISXyP" role="1ojpOf">
+                          <property role="TrG5h" value="bar" />
+                        </node>
+                      </node>
+                      <node concept="1oi5UN" id="4$OyT8ISXyQ" role="KCVpo">
+                        <node concept="1oi5Wm" id="4$OyT8ISXyR" role="1ojpOf">
+                          <property role="TrG5h" value="baz" />
+                        </node>
+                      </node>
+                      <node concept="1oi5UN" id="4$OyT8ISXyS" role="KCVpo">
+                        <node concept="1oi5Wm" id="4$OyT8ISXyT" role="1ojpOf">
+                          <property role="TrG5h" value="qux" />
+                        </node>
                       </node>
                     </node>
-                    <node concept="1oi5UN" id="4$OyT8ISXyQ" role="KCVpo">
-                      <node concept="1oi5Wm" id="4$OyT8ISXyR" role="1ojpOf">
-                        <property role="TrG5h" value="baz" />
-                      </node>
-                    </node>
-                    <node concept="1oi5UN" id="4$OyT8ISXyS" role="KCVpo">
-                      <node concept="1oi5Wm" id="4$OyT8ISXyT" role="1ojpOf">
-                        <property role="TrG5h" value="qux" />
+                  </node>
+                  <node concept="1oi1Uc" id="4$OyT8ISnx$" role="37wK5m">
+                    <node concept="1oi5UN" id="4$OyT8ISnx_" role="1oi0x0">
+                      <node concept="22Ky0T" id="4$OyT8ISnxA" role="lGtFl">
+                        <node concept="37vLTw" id="4$OyT8ISnxB" role="22Ky0K">
+                          <ref role="3cqZAo" node="4$OyT8ISnwA" resolve="tail" />
+                        </node>
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="4$OyT8ISnx$" role="37wK5m">
-                  <node concept="1oi5UN" id="4$OyT8ISnx_" role="1oi0x0">
-                    <node concept="22Ky0T" id="4$OyT8ISnxA" role="lGtFl">
-                      <node concept="37vLTw" id="4$OyT8ISnxB" role="22Ky0K">
-                        <ref role="3cqZAo" node="4$OyT8ISnwA" resolve="tail" />
-                      </node>
-                    </node>
-                  </node>
+                <node concept="37vLTw" id="5jCHAT2dOml" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -4340,16 +4499,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8ITVLH" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="4$OyT8ITVLI" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2ifIk" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="4$OyT8ITVLJ" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ITVL6" resolve="list1" />
+                  </node>
+                  <node concept="37vLTw" id="4$OyT8ITVLK" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ITVLt" resolve="pattern1" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="4$OyT8ITVLJ" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ITVL6" resolve="list1" />
-                </node>
-                <node concept="37vLTw" id="4$OyT8ITVLK" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ITVLt" resolve="pattern1" />
+                <node concept="37vLTw" id="5jCHAT2ighX" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -4379,16 +4541,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8IUgQ0" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="4$OyT8IUgQ1" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2igry" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="3L9quO9YXBu" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8ITVLo" resolve="tail1" />
+                  </node>
+                  <node concept="37vLTw" id="4$OyT8IUimL" role="37wK5m">
+                    <ref role="3cqZAo" node="4$OyT8IUeDt" resolve="pattern2" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="3L9quO9YXBu" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8ITVLo" resolve="tail1" />
-                </node>
-                <node concept="37vLTw" id="4$OyT8IUimL" role="37wK5m">
-                  <ref role="3cqZAo" node="4$OyT8IUeDt" resolve="pattern2" />
+                <node concept="37vLTw" id="5jCHAT2igNq" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -4419,33 +4584,36 @@
                 </node>
               </node>
               <node concept="liA8E" id="4$OyT8ITVM5" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-                <node concept="10M0yZ" id="4$OyT8ITVM6" role="37wK5m">
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-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
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-                <node concept="1oi1Uc" id="4$OyT8ITVM7" role="37wK5m">
-                  <node concept="KCUsM" id="4$OyT8ITVM8" role="1oi0x0">
-                    <node concept="1oi5UN" id="4$OyT8ITVMb" role="KCVpo">
-                      <node concept="1oi5Wm" id="4$OyT8ITVMc" role="1ojpOf">
-                        <property role="TrG5h" value="baz" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+                <node concept="2YIFZM" id="5jCHAT2dSQ7" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="1oi1Uc" id="4$OyT8ITVM7" role="37wK5m">
+                    <node concept="KCUsM" id="4$OyT8ITVM8" role="1oi0x0">
+                      <node concept="1oi5UN" id="4$OyT8ITVMb" role="KCVpo">
+                        <node concept="1oi5Wm" id="4$OyT8ITVMc" role="1ojpOf">
+                          <property role="TrG5h" value="baz" />
+                        </node>
+                      </node>
+                      <node concept="1oi5UN" id="4$OyT8ITVMd" role="KCVpo">
+                        <node concept="1oi5Wm" id="4$OyT8ITVMe" role="1ojpOf">
+                          <property role="TrG5h" value="qux" />
+                        </node>
                       </node>
                     </node>
-                    <node concept="1oi5UN" id="4$OyT8ITVMd" role="KCVpo">
-                      <node concept="1oi5Wm" id="4$OyT8ITVMe" role="1ojpOf">
-                        <property role="TrG5h" value="qux" />
+                  </node>
+                  <node concept="1oi1Uc" id="4$OyT8ITVMf" role="37wK5m">
+                    <node concept="1oi5UN" id="4$OyT8ITVMg" role="1oi0x0">
+                      <node concept="22Ky0T" id="4$OyT8ITVMh" role="lGtFl">
+                        <node concept="37vLTw" id="4$OyT8IUlja" role="22Ky0K">
+                          <ref role="3cqZAo" node="4$OyT8IUcuk" resolve="tail2" />
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                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="4$OyT8ITVMf" role="37wK5m">
-                  <node concept="1oi5UN" id="4$OyT8ITVMg" role="1oi0x0">
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-                        <ref role="3cqZAo" node="4$OyT8IUcuk" resolve="tail2" />
-                      </node>
-                    </node>
-                  </node>
+                <node concept="37vLTw" id="5jCHAT2dTbg" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
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               </node>
             </node>
diff --git a/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util@tests.mps b/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util@tests.mps
index a3e5f48b..04e8adb3 100644
--- a/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util@tests.mps
+++ b/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util@tests.mps
@@ -13,10 +13,18 @@
     <import index="cxk7" ref="r:daa544a7-0a5c-49c0-a54c-4c2a5b4868aa(jetbrains.mps.logic.builtin.predicate)" />
     <import index="zx3l" ref="bbf5c548-7111-4a53-a117-cdefc664cf34/java:jetbrains.mps.logic.reactor.core(jetbrains.mps.logic.reactor/)" />
     <import index="6exd" ref="r:0f9b1fb3-00f9-4480-b235-1a906a087ab2(jetbrains.mps.logic.treeform)" />
+    <import index="bj13" ref="bbf5c548-7111-4a53-a117-cdefc664cf34/java:jetbrains.mps.logic.reactor.logical(jetbrains.mps.logic.reactor/)" />
+    <import index="wyt6" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.lang(JDK/)" implicit="true" />
   </imports>
   <registry>
     <language id="f3061a53-9226-4cc5-a443-f952ceaf5816" name="jetbrains.mps.baseLanguage">
       <concept id="1202948039474" name="jetbrains.mps.baseLanguage.structure.InstanceMethodCallOperation" flags="nn" index="liA8E" />
+      <concept id="1188207840427" name="jetbrains.mps.baseLanguage.structure.AnnotationInstance" flags="nn" index="2AHcQZ">
+        <reference id="1188208074048" name="annotation" index="2AI5Lk" />
+      </concept>
+      <concept id="1188208481402" name="jetbrains.mps.baseLanguage.structure.HasAnnotation" flags="ng" index="2AJDlI">
+        <child id="1188208488637" name="annotation" index="2AJF6D" />
+      </concept>
       <concept id="1197027756228" name="jetbrains.mps.baseLanguage.structure.DotExpression" flags="nn" index="2OqwBi">
         <child id="1197027771414" name="operand" index="2Oq$k0" />
         <child id="1197027833540" name="operation" index="2OqNvi" />
@@ -30,27 +38,48 @@
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
+      <concept id="1182160077978" name="jetbrains.mps.baseLanguage.structure.AnonymousClassCreator" flags="nn" index="YeOm9">
+        <child id="1182160096073" name="cls" index="YeSDq" />
+      </concept>
       <concept id="1081236700937" name="jetbrains.mps.baseLanguage.structure.StaticMethodCall" flags="nn" index="2YIFZM">
         <reference id="1144433194310" name="classConcept" index="1Pybhc" />
       </concept>
+      <concept id="1164991038168" name="jetbrains.mps.baseLanguage.structure.ThrowStatement" flags="nn" index="YS8fn">
+        <child id="1164991057263" name="throwable" index="YScLw" />
+      </concept>
       <concept id="1070533707846" name="jetbrains.mps.baseLanguage.structure.StaticFieldReference" flags="nn" index="10M0yZ">
         <reference id="1144433057691" name="classifier" index="1PxDUh" />
       </concept>
       <concept id="1070534058343" name="jetbrains.mps.baseLanguage.structure.NullLiteral" flags="nn" index="10Nm6u" />
       <concept id="1070534644030" name="jetbrains.mps.baseLanguage.structure.BooleanType" flags="in" index="10P_77" />
+      <concept id="1068390468200" name="jetbrains.mps.baseLanguage.structure.FieldDeclaration" flags="ig" index="312cEg" />
       <concept id="1068431474542" name="jetbrains.mps.baseLanguage.structure.VariableDeclaration" flags="ng" index="33uBYm">
         <child id="1068431790190" name="initializer" index="33vP2m" />
       </concept>
+      <concept id="1109279763828" name="jetbrains.mps.baseLanguage.structure.TypeVariableDeclaration" flags="ng" index="16euLQ" />
+      <concept id="1109279851642" name="jetbrains.mps.baseLanguage.structure.GenericDeclaration" flags="ng" index="16eOlS">
+        <child id="1109279881614" name="typeVariableDeclaration" index="16eVyc" />
+      </concept>
+      <concept id="1109283449304" name="jetbrains.mps.baseLanguage.structure.TypeVariableReference" flags="in" index="16syzq">
+        <reference id="1109283546497" name="typeVariableDeclaration" index="16sUi3" />
+      </concept>
       <concept id="1068498886296" name="jetbrains.mps.baseLanguage.structure.VariableReference" flags="nn" index="37vLTw">
         <reference id="1068581517664" name="variableDeclaration" index="3cqZAo" />
       </concept>
+      <concept id="1068498886292" name="jetbrains.mps.baseLanguage.structure.ParameterDeclaration" flags="ir" index="37vLTG" />
       <concept id="4972933694980447171" name="jetbrains.mps.baseLanguage.structure.BaseVariableDeclaration" flags="ng" index="19Szcq">
         <child id="5680397130376446158" name="type" index="1tU5fm" />
       </concept>
       <concept id="1068580123132" name="jetbrains.mps.baseLanguage.structure.BaseMethodDeclaration" flags="ng" index="3clF44">
+        <property id="4276006055363816570" name="isSynchronized" index="od$2w" />
+        <property id="1181808852946" name="isFinal" index="DiZV1" />
         <child id="1068580123133" name="returnType" index="3clF45" />
+        <child id="1068580123134" name="parameter" index="3clF46" />
         <child id="1068580123135" name="body" index="3clF47" />
       </concept>
+      <concept id="1068580123165" name="jetbrains.mps.baseLanguage.structure.InstanceMethodDeclaration" flags="ig" index="3clFb_">
+        <property id="1178608670077" name="isAbstract" index="1EzhhJ" />
+      </concept>
       <concept id="1068580123155" name="jetbrains.mps.baseLanguage.structure.ExpressionStatement" flags="nn" index="3clFbF">
         <child id="1068580123156" name="expression" index="3clFbG" />
       </concept>
@@ -70,6 +99,10 @@
       <concept id="1212685548494" name="jetbrains.mps.baseLanguage.structure.ClassCreator" flags="nn" index="1pGfFk">
         <child id="1212687122400" name="typeParameter" index="1pMfVU" />
       </concept>
+      <concept id="1107461130800" name="jetbrains.mps.baseLanguage.structure.Classifier" flags="ng" index="3pOWGL">
+        <property id="521412098689998745" name="nonStatic" index="2bfB8j" />
+        <child id="5375687026011219971" name="member" index="jymVt" unordered="true" />
+      </concept>
       <concept id="1107535904670" name="jetbrains.mps.baseLanguage.structure.ClassifierType" flags="in" index="3uibUv">
         <reference id="1107535924139" name="classifier" index="3uigEE" />
         <child id="1109201940907" name="parameter" index="11_B2D" />
@@ -84,6 +117,10 @@
         <child id="6329021646629175155" name="commentPart" index="3SKWNk" />
       </concept>
       <concept id="1146644602865" name="jetbrains.mps.baseLanguage.structure.PublicVisibility" flags="nn" index="3Tm1VV" />
+      <concept id="1146644623116" name="jetbrains.mps.baseLanguage.structure.PrivateVisibility" flags="nn" index="3Tm6S6" />
+      <concept id="1170345865475" name="jetbrains.mps.baseLanguage.structure.AnonymousClass" flags="ig" index="1Y3b0j">
+        <reference id="1170346070688" name="classifier" index="1Y3XeK" />
+      </concept>
     </language>
     <language id="f61473f9-130f-42f6-b98d-6c438812c2f6" name="jetbrains.mps.baseLanguage.unitTest">
       <concept id="1171931690126" name="jetbrains.mps.baseLanguage.unitTest.structure.TestMethod" flags="ig" index="3s$Bmu">
@@ -132,6 +169,63 @@
   </registry>
   <node concept="3s_ewN" id="7t5VLKGALSG">
     <property role="3s_ewP" value="Lub" />
+    <node concept="312cEg" id="5jCHAT2dJM2" role="jymVt">
+      <property role="TrG5h" value="NO_CONTEXT" />
+      <node concept="3Tm6S6" id="5jCHAT2dJM3" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2dKeE" role="1tU5fm">
+        <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
+      </node>
+      <node concept="2ShNRf" id="5jCHAT2dKg0" role="33vP2m">
+        <node concept="YeOm9" id="5jCHAT2dKnF" role="2ShVmc">
+          <node concept="1Y3b0j" id="5jCHAT2dKnI" role="YeSDq">
+            <property role="2bfB8j" value="true" />
+            <ref role="1Y3XeK" to="bj13:~LogicalContext" resolve="LogicalContext" />
+            <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+            <node concept="3Tm1VV" id="5jCHAT2dKnJ" role="1B3o_S" />
+            <node concept="3clFb_" id="5jCHAT2dKnK" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="variable" />
+              <property role="DiZV1" value="false" />
+              <property role="od$2w" value="false" />
+              <node concept="3Tm1VV" id="5jCHAT2dKnL" role="1B3o_S" />
+              <node concept="16euLQ" id="5jCHAT2dKnN" role="16eVyc">
+                <property role="TrG5h" value="V" />
+              </node>
+              <node concept="3uibUv" id="5jCHAT2dKnO" role="3clF45">
+                <ref role="3uigEE" to="bj13:~Logical" resolve="Logical" />
+                <node concept="16syzq" id="5jCHAT2dKnP" role="11_B2D">
+                  <ref role="16sUi3" node="5jCHAT2dKnN" resolve="V" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="5jCHAT2dKnQ" role="3clF46">
+                <property role="TrG5h" value="p0" />
+                <node concept="3uibUv" id="5jCHAT2dKnR" role="1tU5fm">
+                  <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  <node concept="16syzq" id="5jCHAT2dKnS" role="11_B2D">
+                    <ref role="16sUi3" node="5jCHAT2dKnN" resolve="V" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbS" id="5jCHAT2dKnT" role="3clF47">
+                <node concept="YS8fn" id="5jCHAT2dKwo" role="3cqZAp">
+                  <node concept="2ShNRf" id="5jCHAT2dKxx" role="YScLw">
+                    <node concept="1pGfFk" id="5jCHAT2dKLh" role="2ShVmc">
+                      <ref role="37wK5l" to="wyt6:~UnsupportedOperationException.&lt;init&gt;(java.lang.String)" resolve="UnsupportedOperationException" />
+                      <node concept="Xl_RD" id="5jCHAT2dKOW" role="37wK5m">
+                        <property role="Xl_RC" value="not implemented" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="2AHcQZ" id="5jCHAT2dNAi" role="2AJF6D">
+                <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
     <node concept="3Tm1VV" id="7t5VLKGALSN" role="1B3o_S" />
     <node concept="3s_gsd" id="7t5VLKGALSO" role="3s_ewO">
       <node concept="3s$Bmu" id="7t5VLKGALSP" role="3s_gse">
@@ -359,16 +453,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_vsV" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_vv8" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i38C" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_vy4" role="37wK5m">
+                    <ref role="3cqZAo" node="4JRKVCv8a6f" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_vy5" role="37wK5m">
+                    <ref role="3cqZAo" node="7t5VLKGALTu" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_vy4" role="37wK5m">
-                  <ref role="3cqZAo" node="4JRKVCv8a6f" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_vy5" role="37wK5m">
-                  <ref role="3cqZAo" node="7t5VLKGALTu" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i3xA" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -614,16 +711,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_vXm" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_vXn" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i00V" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_vXo" role="37wK5m">
+                    <ref role="3cqZAo" node="7t5VLKGALUW" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_vXp" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7RDU" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_vXo" role="37wK5m">
-                  <ref role="3cqZAo" node="7t5VLKGALUW" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_vXp" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7RDU" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i0qO" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -855,16 +955,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_wcd" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_wce" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i0CB" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_wcf" role="37wK5m">
+                    <ref role="3cqZAo" node="7t5VLKGALWf" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_wcg" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7ovF" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_wcf" role="37wK5m">
-                  <ref role="3cqZAo" node="7t5VLKGALWf" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_wcg" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7ovF" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i12C" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -1124,16 +1227,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_w_j" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_w_k" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i2vU" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_w_l" role="37wK5m">
+                    <ref role="3cqZAo" node="7t5VLKGALXG" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_w_m" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7saF" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_w_l" role="37wK5m">
-                  <ref role="3cqZAo" node="7t5VLKGALXG" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_w_m" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7saF" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i2Uj" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -1548,16 +1654,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_wPv" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_wPw" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2hZnc" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_wPx" role="37wK5m">
+                    <ref role="3cqZAo" node="7t5VLKGALZK" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_wPy" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7vK4" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_wPx" role="37wK5m">
-                  <ref role="3cqZAo" node="7t5VLKGALZK" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_wPy" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7vK4" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2hZNg" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -2031,16 +2140,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_x7E" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_x7F" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2hYBO" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_x7G" role="37wK5m">
+                    <ref role="3cqZAo" node="3hfdu5cNgsA" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_x7H" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7zha" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_x7G" role="37wK5m">
-                  <ref role="3cqZAo" node="3hfdu5cNgsA" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_x7H" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7zha" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2hZ15" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -2571,16 +2683,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_xqU" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_xqV" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i1gz" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_xqW" role="37wK5m">
+                    <ref role="3cqZAo" node="3KV3FXk2oKs" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_xqX" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7AXX" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_xqW" role="37wK5m">
-                  <ref role="3cqZAo" node="3KV3FXk2oKs" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_xqX" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7AXX" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i1EG" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3032,16 +3147,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_xIn" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_xIo" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2hXW8" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_xIp" role="37wK5m">
+                    <ref role="3cqZAo" node="3hfdu5cN_MP" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_xIq" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7Ejv" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_xIp" role="37wK5m">
-                  <ref role="3cqZAo" node="3hfdu5cN_MP" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_xIq" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7Ejv" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2hYqp" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3517,16 +3635,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_y11" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_y12" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i1SJ" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_y13" role="37wK5m">
+                    <ref role="3cqZAo" node="3KV3FXjXcrs" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_y14" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7HxN" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_y13" role="37wK5m">
-                  <ref role="3cqZAo" node="3KV3FXjXcrs" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_y14" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7HxN" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i2hH" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3864,16 +3985,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_yj8" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_yj9" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2hXkk" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_yja" role="37wK5m">
+                    <ref role="3cqZAo" node="3KV3FXk18Pu" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_yjb" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7KDC" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_yja" role="37wK5m">
-                  <ref role="3cqZAo" node="3KV3FXk18Pu" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_yjb" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7KDC" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2hXHQ" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2dJM2" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
@@ -3931,6 +4055,63 @@
   </node>
   <node concept="3s_ewN" id="3KV3FXk2b2J">
     <property role="3s_ewP" value="SubtypePath" />
+    <node concept="312cEg" id="5jCHAT2i6xk" role="jymVt">
+      <property role="TrG5h" value="NO_CONTEXT" />
+      <node concept="3Tm6S6" id="5jCHAT2i6xl" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2i6xm" role="1tU5fm">
+        <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
+      </node>
+      <node concept="2ShNRf" id="5jCHAT2i6xn" role="33vP2m">
+        <node concept="YeOm9" id="5jCHAT2i6xo" role="2ShVmc">
+          <node concept="1Y3b0j" id="5jCHAT2i6xp" role="YeSDq">
+            <property role="2bfB8j" value="true" />
+            <ref role="1Y3XeK" to="bj13:~LogicalContext" resolve="LogicalContext" />
+            <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+            <node concept="3Tm1VV" id="5jCHAT2i6xq" role="1B3o_S" />
+            <node concept="3clFb_" id="5jCHAT2i6xr" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="variable" />
+              <property role="DiZV1" value="false" />
+              <property role="od$2w" value="false" />
+              <node concept="3Tm1VV" id="5jCHAT2i6xs" role="1B3o_S" />
+              <node concept="16euLQ" id="5jCHAT2i6xt" role="16eVyc">
+                <property role="TrG5h" value="V" />
+              </node>
+              <node concept="3uibUv" id="5jCHAT2i6xu" role="3clF45">
+                <ref role="3uigEE" to="bj13:~Logical" resolve="Logical" />
+                <node concept="16syzq" id="5jCHAT2i6xv" role="11_B2D">
+                  <ref role="16sUi3" node="5jCHAT2i6xt" resolve="V" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="5jCHAT2i6xw" role="3clF46">
+                <property role="TrG5h" value="p0" />
+                <node concept="3uibUv" id="5jCHAT2i6xx" role="1tU5fm">
+                  <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  <node concept="16syzq" id="5jCHAT2i6xy" role="11_B2D">
+                    <ref role="16sUi3" node="5jCHAT2i6xt" resolve="V" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbS" id="5jCHAT2i6xz" role="3clF47">
+                <node concept="YS8fn" id="5jCHAT2i6x$" role="3cqZAp">
+                  <node concept="2ShNRf" id="5jCHAT2i6x_" role="YScLw">
+                    <node concept="1pGfFk" id="5jCHAT2i6xA" role="2ShVmc">
+                      <ref role="37wK5l" to="wyt6:~UnsupportedOperationException.&lt;init&gt;(java.lang.String)" resolve="UnsupportedOperationException" />
+                      <node concept="Xl_RD" id="5jCHAT2i6xB" role="37wK5m">
+                        <property role="Xl_RC" value="not implemented" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="2AHcQZ" id="5jCHAT2i6xC" role="2AJF6D">
+                <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
     <node concept="3Tm1VV" id="3KV3FXk2b2K" role="1B3o_S" />
     <node concept="3s_gsd" id="3KV3FXk2b2L" role="3s_ewO">
       <node concept="3s$Bmu" id="3KV3FXk2boI" role="3s_gse">
@@ -4276,16 +4457,19 @@
                 </node>
               </node>
               <node concept="liA8E" id="5jPBdK_R$W" role="2OqNvi">
-                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                <node concept="10M0yZ" id="5jPBdK_R$X" role="37wK5m">
-                  <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                  <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                <node concept="2YIFZM" id="5jCHAT2i4iC" role="37wK5m">
+                  <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                  <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                  <node concept="37vLTw" id="5jPBdK_R$Y" role="37wK5m">
+                    <ref role="3cqZAo" node="3KV3FXk2bqn" resolve="expect" />
+                  </node>
+                  <node concept="37vLTw" id="5jPBdK_R$Z" role="37wK5m">
+                    <ref role="3cqZAo" node="6yEjedm7VYw" resolve="var" />
+                  </node>
                 </node>
-                <node concept="37vLTw" id="5jPBdK_R$Y" role="37wK5m">
-                  <ref role="3cqZAo" node="3KV3FXk2bqn" resolve="expect" />
-                </node>
-                <node concept="37vLTw" id="5jPBdK_R$Z" role="37wK5m">
-                  <ref role="3cqZAo" node="6yEjedm7VYw" resolve="var" />
+                <node concept="37vLTw" id="5jCHAT2i7ks" role="37wK5m">
+                  <ref role="3cqZAo" node="5jCHAT2i6xk" resolve="NO_CONTEXT" />
                 </node>
               </node>
             </node>
diff --git a/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.util/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/util.mps b/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.util/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/util.mps
index 87b5e079..ab213a49 100644
--- a/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.util/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/util.mps
+++ b/typechecking/solutions/jetbrains.mps.lang.typesystem2.samplechecker.handler.util/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/util.mps
@@ -51,6 +51,12 @@
         <child id="1173175577737" name="index" index="AHEQo" />
         <child id="1173175590490" name="array" index="AHHXb" />
       </concept>
+      <concept id="1188207840427" name="jetbrains.mps.baseLanguage.structure.AnnotationInstance" flags="nn" index="2AHcQZ">
+        <reference id="1188208074048" name="annotation" index="2AI5Lk" />
+      </concept>
+      <concept id="1188208481402" name="jetbrains.mps.baseLanguage.structure.HasAnnotation" flags="ng" index="2AJDlI">
+        <child id="1188208488637" name="annotation" index="2AJF6D" />
+      </concept>
       <concept id="1461424660015405635" name="jetbrains.mps.baseLanguage.structure.EscapeOperation" flags="nn" index="EvHYZ" />
       <concept id="1224848483129" name="jetbrains.mps.baseLanguage.structure.IBLDeprecatable" flags="ng" index="IEa8$">
         <property id="1224848525476" name="isDeprecated" index="IEkAT" />
@@ -82,12 +88,15 @@
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
+      <concept id="1182160077978" name="jetbrains.mps.baseLanguage.structure.AnonymousClassCreator" flags="nn" index="YeOm9">
+        <child id="1182160096073" name="cls" index="YeSDq" />
+      </concept>
       <concept id="1081236700938" name="jetbrains.mps.baseLanguage.structure.StaticMethodDeclaration" flags="ig" index="2YIFZL" />
       <concept id="1081236700937" name="jetbrains.mps.baseLanguage.structure.StaticMethodCall" flags="nn" index="2YIFZM">
         <reference id="1144433194310" name="classConcept" index="1Pybhc" />
       </concept>
-      <concept id="1070533707846" name="jetbrains.mps.baseLanguage.structure.StaticFieldReference" flags="nn" index="10M0yZ">
-        <reference id="1144433057691" name="classifier" index="1PxDUh" />
+      <concept id="1164991038168" name="jetbrains.mps.baseLanguage.structure.ThrowStatement" flags="nn" index="YS8fn">
+        <child id="1164991057263" name="throwable" index="YScLw" />
       </concept>
       <concept id="1070534058343" name="jetbrains.mps.baseLanguage.structure.NullLiteral" flags="nn" index="10Nm6u" />
       <concept id="1070534370425" name="jetbrains.mps.baseLanguage.structure.IntegerType" flags="in" index="10Oyi0" />
@@ -104,6 +113,13 @@
         <property id="1176718929932" name="isFinal" index="3TUv4t" />
         <child id="1068431790190" name="initializer" index="33vP2m" />
       </concept>
+      <concept id="1109279763828" name="jetbrains.mps.baseLanguage.structure.TypeVariableDeclaration" flags="ng" index="16euLQ" />
+      <concept id="1109279851642" name="jetbrains.mps.baseLanguage.structure.GenericDeclaration" flags="ng" index="16eOlS">
+        <child id="1109279881614" name="typeVariableDeclaration" index="16eVyc" />
+      </concept>
+      <concept id="1109283449304" name="jetbrains.mps.baseLanguage.structure.TypeVariableReference" flags="in" index="16syzq">
+        <reference id="1109283546497" name="typeVariableDeclaration" index="16sUi3" />
+      </concept>
       <concept id="1068498886296" name="jetbrains.mps.baseLanguage.structure.VariableReference" flags="nn" index="37vLTw">
         <reference id="1068581517664" name="variableDeclaration" index="3cqZAo" />
       </concept>
@@ -120,7 +136,9 @@
         <child id="1068580123134" name="parameter" index="3clF46" />
         <child id="1068580123135" name="body" index="3clF47" />
       </concept>
-      <concept id="1068580123165" name="jetbrains.mps.baseLanguage.structure.InstanceMethodDeclaration" flags="ig" index="3clFb_" />
+      <concept id="1068580123165" name="jetbrains.mps.baseLanguage.structure.InstanceMethodDeclaration" flags="ig" index="3clFb_">
+        <property id="1178608670077" name="isAbstract" index="1EzhhJ" />
+      </concept>
       <concept id="1068580123152" name="jetbrains.mps.baseLanguage.structure.EqualsExpression" flags="nn" index="3clFbC" />
       <concept id="1068580123155" name="jetbrains.mps.baseLanguage.structure.ExpressionStatement" flags="nn" index="3clFbF">
         <child id="1068580123156" name="expression" index="3clFbG" />
@@ -171,6 +189,7 @@
         <child id="1212687122400" name="typeParameter" index="1pMfVU" />
       </concept>
       <concept id="1107461130800" name="jetbrains.mps.baseLanguage.structure.Classifier" flags="ng" index="3pOWGL">
+        <property id="521412098689998745" name="nonStatic" index="2bfB8j" />
         <child id="5375687026011219971" name="member" index="jymVt" unordered="true" />
       </concept>
       <concept id="1171903916106" name="jetbrains.mps.baseLanguage.structure.UpperBoundType" flags="in" index="3qUE_q">
@@ -219,6 +238,9 @@
       <concept id="1146644623116" name="jetbrains.mps.baseLanguage.structure.PrivateVisibility" flags="nn" index="3Tm6S6" />
       <concept id="1146644641414" name="jetbrains.mps.baseLanguage.structure.ProtectedVisibility" flags="nn" index="3Tmbuc" />
       <concept id="1080120340718" name="jetbrains.mps.baseLanguage.structure.AndExpression" flags="nn" index="1Wc70l" />
+      <concept id="1170345865475" name="jetbrains.mps.baseLanguage.structure.AnonymousClass" flags="ig" index="1Y3b0j">
+        <reference id="1170346070688" name="classifier" index="1Y3XeK" />
+      </concept>
     </language>
     <language id="f2801650-65d5-424e-bb1b-463a8781b786" name="jetbrains.mps.baseLanguage.javadoc">
       <concept id="2546654756694997551" name="jetbrains.mps.baseLanguage.javadoc.structure.LinkInlineDocTag" flags="ng" index="92FcH">
@@ -534,20 +556,23 @@
                     <ref role="3cqZAo" node="5uFPQ7ClQgr" resolve="sessionSolver" />
                   </node>
                   <node concept="liA8E" id="3KV3FXjZMUJ" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                    <node concept="10M0yZ" id="3KV3FXjZMUK" role="37wK5m">
-                      <ref role="3cqZAo" to="cxk7:5uFPQ7C23RV" resolve="EQ_SYM" />
-                      <ref role="1PxDUh" to="cxk7:3HJTsBn4kk_" resolve="EqualsPredicate" />
-                    </node>
-                    <node concept="37vLTw" id="3KV3FXjZMUL" role="37wK5m">
-                      <ref role="3cqZAo" node="5H6hZahmlpn" resolve="result" />
-                    </node>
-                    <node concept="2YIFZM" id="3KV3FXk1qgA" role="37wK5m">
-                      <ref role="37wK5l" node="5H6hZahoMly" resolve="buildResult" />
-                      <ref role="1Pybhc" node="3KV3FXk1mCr" resolve="AbstractSolver" />
-                      <node concept="37vLTw" id="3KV3FXjZMUP" role="37wK5m">
-                        <ref role="3cqZAo" node="3KV3FXk0pld" resolve="resultList" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                    <node concept="2YIFZM" id="5jCHAT2ivhn" role="37wK5m">
+                      <ref role="37wK5l" to="cxk7:5jCHAT2iqus" resolve="eq" />
+                      <ref role="1Pybhc" to="cxk7:3HJTsBn4kk_" resolve="EqualsPredicate" />
+                      <node concept="37vLTw" id="3KV3FXjZMUL" role="37wK5m">
+                        <ref role="3cqZAo" node="5H6hZahmlpn" resolve="result" />
                       </node>
+                      <node concept="2YIFZM" id="3KV3FXk1qgA" role="37wK5m">
+                        <ref role="37wK5l" node="5H6hZahoMly" resolve="buildResult" />
+                        <ref role="1Pybhc" node="3KV3FXk1mCr" resolve="AbstractSolver" />
+                        <node concept="37vLTw" id="3KV3FXjZMUP" role="37wK5m">
+                          <ref role="3cqZAo" node="3KV3FXk0pld" resolve="resultList" />
+                        </node>
+                      </node>
+                    </node>
+                    <node concept="37vLTw" id="5jCHAT2ivNL" role="37wK5m">
+                      <ref role="3cqZAo" node="5jCHAT2dL9L" resolve="NO_CONTEXT" />
                     </node>
                   </node>
                 </node>
@@ -1585,7 +1610,7 @@
     <node concept="3clFbW" id="3KV3FXjZFyb" role="jymVt">
       <node concept="37vLTG" id="3KV3FXjZFT2" role="3clF46">
         <property role="TrG5h" value="sessionSolver" />
-        <node concept="3uibUv" id="3KV3FXjZFTc" role="1tU5fm">
+        <node concept="3uibUv" id="5jCHAT2FfMi" role="1tU5fm">
           <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
         </node>
       </node>
@@ -1853,7 +1878,7 @@
         <node concept="3clFbH" id="3KV3FXk1j8I" role="3cqZAp" />
         <node concept="3cpWs8" id="5uFPQ7ClVCJ" role="3cqZAp">
           <node concept="3cpWsn" id="5uFPQ7ClVCK" role="3cpWs9">
-            <property role="TrG5h" value="computingSession" />
+            <property role="TrG5h" value="sessionSolver" />
             <node concept="3uibUv" id="5uFPQ7ClVCL" role="1tU5fm">
               <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
             </node>
@@ -1882,7 +1907,7 @@
                 <node concept="1pGfFk" id="3KV3FXk1kuc" role="2ShVmc">
                   <ref role="37wK5l" node="3KV3FXk1jky" resolve="SubtypePathSolver" />
                   <node concept="37vLTw" id="3KV3FXk1kud" role="37wK5m">
-                    <ref role="3cqZAo" node="5uFPQ7ClVCK" resolve="computingSession" />
+                    <ref role="3cqZAo" node="5uFPQ7ClVCK" resolve="sessionSolver" />
                   </node>
                 </node>
               </node>
@@ -1938,23 +1963,26 @@
               <node concept="3clFbF" id="3KV3FXk1m38" role="3cqZAp">
                 <node concept="2OqwBi" id="3KV3FXk1m39" role="3clFbG">
                   <node concept="37vLTw" id="3KV3FXk1m3a" role="2Oq$k0">
-                    <ref role="3cqZAo" node="5uFPQ7ClVCK" resolve="computingSession" />
+                    <ref role="3cqZAo" node="5uFPQ7ClVCK" resolve="sessionSolver" />
                   </node>
                   <node concept="liA8E" id="3KV3FXk1m3b" role="2OqNvi">
-                    <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.Symbol,java.lang.Object...):void" resolve="tell" />
-                    <node concept="10M0yZ" id="3KV3FXk1m3c" role="37wK5m">
-                      <ref role="3cqZAo" to="cxk7:5uFPQ7C23RV" resolve="EQ_SYM" />
-                      <ref role="1PxDUh" to="cxk7:3HJTsBn4kk_" resolve="EqualsPredicate" />
-                    </node>
-                    <node concept="37vLTw" id="3KV3FXk1m3d" role="37wK5m">
-                      <ref role="3cqZAo" node="3KV3FXk1fGz" resolve="result" />
-                    </node>
-                    <node concept="2YIFZM" id="3KV3FXk1m8m" role="37wK5m">
-                      <ref role="1Pybhc" node="3KV3FXk1mCr" resolve="AbstractSolver" />
-                      <ref role="37wK5l" node="5H6hZahoMly" resolve="buildResult" />
-                      <node concept="37vLTw" id="3KV3FXk1m3h" role="37wK5m">
-                        <ref role="3cqZAo" node="3KV3FXk1ku9" resolve="resultList" />
+                    <ref role="37wK5l" to="w7la:~SessionSolver.tell(jetbrains.mps.logic.reactor.program.AndItem,jetbrains.mps.logic.reactor.logical.LogicalContext):void" resolve="tell" />
+                    <node concept="2YIFZM" id="5jCHAT2itK8" role="37wK5m">
+                      <ref role="37wK5l" to="cxk7:5jCHAT2iqus" resolve="eq" />
+                      <ref role="1Pybhc" to="cxk7:3HJTsBn4kk_" resolve="EqualsPredicate" />
+                      <node concept="37vLTw" id="3KV3FXk1m3d" role="37wK5m">
+                        <ref role="3cqZAo" node="3KV3FXk1fGz" resolve="result" />
                       </node>
+                      <node concept="2YIFZM" id="3KV3FXk1m8m" role="37wK5m">
+                        <ref role="1Pybhc" node="3KV3FXk1mCr" resolve="AbstractSolver" />
+                        <ref role="37wK5l" node="5H6hZahoMly" resolve="buildResult" />
+                        <node concept="37vLTw" id="3KV3FXk1m3h" role="37wK5m">
+                          <ref role="3cqZAo" node="3KV3FXk1ku9" resolve="resultList" />
+                        </node>
+                      </node>
+                    </node>
+                    <node concept="37vLTw" id="5jCHAT2iu$S" role="37wK5m">
+                      <ref role="3cqZAo" node="5jCHAT2dL9L" resolve="NO_CONTEXT" />
                     </node>
                   </node>
                 </node>
@@ -2459,13 +2487,13 @@
         <node concept="XkiVB" id="3KV3FXk1$Vg" role="3cqZAp">
           <ref role="37wK5l" node="3KV3FXk1tGv" resolve="AbstractSolver" />
           <node concept="37vLTw" id="3KV3FXk1$VL" role="37wK5m">
-            <ref role="3cqZAo" node="3KV3FXk1jlA" resolve="computingSession" />
+            <ref role="3cqZAo" node="3KV3FXk1jlA" resolve="sessionSolver" />
           </node>
         </node>
       </node>
       <node concept="37vLTG" id="3KV3FXk1jlA" role="3clF46">
-        <property role="TrG5h" value="computingSession" />
-        <node concept="3uibUv" id="3KV3FXk1jl_" role="1tU5fm">
+        <property role="TrG5h" value="sessionSolver" />
+        <node concept="3uibUv" id="5jCHAT2FkcL" role="1tU5fm">
           <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
         </node>
       </node>
@@ -2661,16 +2689,19 @@
               <ref role="3cqZAo" node="3KV3FXjZFTt" resolve="sessionSolver" />
             </node>
             <node concept="liA8E" id="3KV3FXjZkQX" role="2OqNvi">
-              <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.PredicateSymbol,java.lang.Object...):boolean" resolve="ask" />
-              <node concept="10M0yZ" id="5uFPQ7C5ZbN" role="37wK5m">
-                <ref role="3cqZAo" to="cxk7:5uFPQ7C29mw" resolve="UNI_SYM" />
-                <ref role="1PxDUh" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+              <ref role="37wK5l" to="w7la:~SessionSolver.ask(jetbrains.mps.logic.reactor.program.Predicate,jetbrains.mps.logic.reactor.logical.LogicalContext):boolean" resolve="ask" />
+              <node concept="2YIFZM" id="5jCHAT29rUQ" role="37wK5m">
+                <ref role="37wK5l" to="cxk7:5jCHAT29qgV" resolve="unifies" />
+                <ref role="1Pybhc" to="cxk7:2GO7tyJVmP4" resolve="UnificationPredicate" />
+                <node concept="37vLTw" id="3KV3FXjZkRO" role="37wK5m">
+                  <ref role="3cqZAo" node="3KV3FXjZkR1" resolve="nextLeft" />
+                </node>
+                <node concept="37vLTw" id="3KV3FXjZkRM" role="37wK5m">
+                  <ref role="3cqZAo" node="3KV3FXjZkR3" resolve="nextRight" />
+                </node>
               </node>
-              <node concept="37vLTw" id="3KV3FXjZkRO" role="37wK5m">
-                <ref role="3cqZAo" node="3KV3FXjZkR1" resolve="nextLeft" />
-              </node>
-              <node concept="37vLTw" id="3KV3FXjZkRM" role="37wK5m">
-                <ref role="3cqZAo" node="3KV3FXjZkR3" resolve="nextRight" />
+              <node concept="37vLTw" id="5jCHAT2dMTY" role="37wK5m">
+                <ref role="3cqZAo" node="5jCHAT2dL9L" resolve="NO_CONTEXT" />
               </node>
             </node>
           </node>
@@ -2773,16 +2804,74 @@
       </node>
       <node concept="37vLTG" id="3KV3FXk1u5_" role="3clF46">
         <property role="TrG5h" value="sessionSolver" />
-        <node concept="3uibUv" id="3KV3FXk1u5$" role="1tU5fm">
+        <node concept="3uibUv" id="5jCHAT2F7UF" role="1tU5fm">
           <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
         </node>
       </node>
     </node>
     <node concept="2tJIrI" id="3KV3FXk1qx0" role="jymVt" />
+    <node concept="Wx3nA" id="5jCHAT2dL9L" role="jymVt">
+      <property role="TrG5h" value="NO_CONTEXT" />
+      <node concept="3Tmbuc" id="5jCHAT2iuoe" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2dLkP" role="1tU5fm">
+        <ref role="3uigEE" to="bj13:~LogicalContext" resolve="LogicalContext" />
+      </node>
+      <node concept="2ShNRf" id="5jCHAT2dLn7" role="33vP2m">
+        <node concept="YeOm9" id="5jCHAT2dLEE" role="2ShVmc">
+          <node concept="1Y3b0j" id="5jCHAT2dLEH" role="YeSDq">
+            <property role="2bfB8j" value="true" />
+            <ref role="1Y3XeK" to="bj13:~LogicalContext" resolve="LogicalContext" />
+            <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+            <node concept="3Tm1VV" id="5jCHAT2dLEI" role="1B3o_S" />
+            <node concept="3clFb_" id="5jCHAT29xqp" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="variable" />
+              <property role="DiZV1" value="false" />
+              <property role="od$2w" value="false" />
+              <node concept="3Tm1VV" id="5jCHAT29xqq" role="1B3o_S" />
+              <node concept="16euLQ" id="5jCHAT29xqs" role="16eVyc">
+                <property role="TrG5h" value="V" />
+              </node>
+              <node concept="3uibUv" id="5jCHAT29xqt" role="3clF45">
+                <ref role="3uigEE" to="bj13:~Logical" resolve="Logical" />
+                <node concept="16syzq" id="5jCHAT29xqu" role="11_B2D">
+                  <ref role="16sUi3" node="5jCHAT29xqs" resolve="V" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="5jCHAT29xqv" role="3clF46">
+                <property role="TrG5h" value="logical" />
+                <node concept="3uibUv" id="5jCHAT29xqw" role="1tU5fm">
+                  <ref role="3uigEE" to="bj13:~MetaLogical" resolve="MetaLogical" />
+                  <node concept="16syzq" id="5jCHAT29xqx" role="11_B2D">
+                    <ref role="16sUi3" node="5jCHAT29xqs" resolve="V" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbS" id="5jCHAT29xqy" role="3clF47">
+                <node concept="YS8fn" id="5jCHAT29xwA" role="3cqZAp">
+                  <node concept="2ShNRf" id="5jCHAT29xxR" role="YScLw">
+                    <node concept="1pGfFk" id="5jCHAT29xQt" role="2ShVmc">
+                      <ref role="37wK5l" to="wyt6:~UnsupportedOperationException.&lt;init&gt;(java.lang.String)" resolve="UnsupportedOperationException" />
+                      <node concept="Xl_RD" id="5jCHAT29xUg" role="37wK5m">
+                        <property role="Xl_RC" value="not implemented" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="2AHcQZ" id="5jCHAT29xqz" role="2AJF6D">
+                <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jCHAT29x36" role="jymVt" />
     <node concept="312cEg" id="3KV3FXjZFTt" role="jymVt">
       <property role="TrG5h" value="sessionSolver" />
-      <node concept="3Tmbuc" id="3KV3FXk1ru9" role="1B3o_S" />
-      <node concept="3uibUv" id="3KV3FXjZFTw" role="1tU5fm">
+      <node concept="3Tm6S6" id="5jCHAT29z1F" role="1B3o_S" />
+      <node concept="3uibUv" id="5jCHAT2F7yC" role="1tU5fm">
         <ref role="3uigEE" to="w7la:~SessionSolver" resolve="SessionSolver" />
       </node>
     </node>
diff --git a/typechecking/solutions/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps b/typechecking/solutions/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
index c5f90615..82e90901 100644
--- a/typechecking/solutions/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
+++ b/typechecking/solutions/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
@@ -5106,8 +5106,8 @@
       </node>
       <node concept="312cEg" id="3F6vMxqlTiX" role="jymVt">
         <property role="TrG5h" value="expressionSolver" />
-        <node concept="3uibUv" id="4n$Qn$04BDj" role="1tU5fm">
-          <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+        <node concept="3uibUv" id="5jCHAT2xOdU" role="1tU5fm">
+          <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
         </node>
         <node concept="3Tm1VV" id="3F6vMxq$S9w" role="1B3o_S" />
       </node>
@@ -5838,8 +5838,8 @@
         <property role="TrG5h" value="createSessionSolver" />
         <node concept="37vLTG" id="3F6vMxqmh0e" role="3clF46">
           <property role="TrG5h" value="expressionSolver" />
-          <node concept="3uibUv" id="1HG00HG2qpP" role="1tU5fm">
-            <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+          <node concept="3uibUv" id="5jCHAT2xK28" role="1tU5fm">
+            <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
           </node>
         </node>
         <node concept="3uibUv" id="3F6vMxqlLKq" role="3clF45">
diff --git a/typesystem2/languages/jetbrains.mps.lang.typesystem2/generator/template/main@generator.mps b/typesystem2/languages/jetbrains.mps.lang.typesystem2/generator/template/main@generator.mps
index 75f65209..f3d48d3f 100644
--- a/typesystem2/languages/jetbrains.mps.lang.typesystem2/generator/template/main@generator.mps
+++ b/typesystem2/languages/jetbrains.mps.lang.typesystem2/generator/template/main@generator.mps
@@ -44,6 +44,7 @@
     <import index="ba7m" ref="r:4c5ac278-3ad7-4902-ab86-6c60b350f168(jetbrains.mps.lang.aspect.generator.template.main@generator)" />
     <import index="fqlx" ref="r:2cc226a9-8a78-4010-b962-823343fd28ff(jetbrains.mps.lang.typesystem2.aspect)" />
     <import index="6exd" ref="r:0f9b1fb3-00f9-4480-b235-1a906a087ab2(jetbrains.mps.logic.treeform)" />
+    <import index="yg8f" ref="r:e213377a-f1a7-4ba7-9d08-96bcb97ed8ce(jetbrains.mps.logic.builtin)" />
     <import index="tpek" ref="r:00000000-0000-4000-0000-011c895902c0(jetbrains.mps.baseLanguage.behavior)" implicit="true" />
     <import index="tpcu" ref="r:00000000-0000-4000-0000-011c89590282(jetbrains.mps.lang.core.behavior)" implicit="true" />
     <import index="c17a" ref="8865b7a8-5271-43d3-884c-6fd1d9cfdd34/java:org.jetbrains.mps.openapi.language(MPS.OpenAPI/)" implicit="true" />
@@ -3946,8 +3947,8 @@
       <property role="DiZV1" value="false" />
       <property role="2aFKle" value="false" />
       <node concept="3Tm1VV" id="1ggxSI7z25J" role="1B3o_S" />
-      <node concept="3uibUv" id="1ggxSI7z25K" role="3clF45">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2vJrl" role="3clF45">
+        <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
       </node>
       <node concept="3clFbS" id="1ggxSI7z25L" role="3clF47">
         <node concept="3clFbF" id="1ggxSI7z28i" role="3cqZAp">
@@ -14520,7 +14521,7 @@
   <node concept="312cEu" id="1sCZQVeRJry">
     <property role="TrG5h" value="ExpressionSolver" />
     <property role="3GE5qa" value="expression" />
-    <node concept="2tJIrI" id="1sCZQVeRJsO" role="jymVt" />
+    <node concept="2tJIrI" id="5jCHAT24Luj" role="jymVt" />
     <node concept="3clFb_" id="2UGjFq4p$z9" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="ask" />
@@ -15052,6 +15053,9 @@
     <node concept="3uibUv" id="6H279bUVoh4" role="EKbjA">
       <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
     </node>
+    <node concept="3uibUv" id="5jCHAT2PtwH" role="1zkMxy">
+      <ref role="3uigEE" to="yg8f:5jCHAT2EKLb" resolve="AbstractLogicSolver" />
+    </node>
   </node>
   <node concept="bUwia" id="1sCZQVeRS5H">
     <property role="TrG5h" value="expression" />
diff --git a/typesystem2/languages/jetbrains.mps.lang.typesystem2/runtime/models/jetbrains/mps/lang/typesystem2/typechecking.mps b/typesystem2/languages/jetbrains.mps.lang.typesystem2/runtime/models/jetbrains/mps/lang/typesystem2/typechecking.mps
index a395274b..69b0ae47 100644
--- a/typesystem2/languages/jetbrains.mps.lang.typesystem2/runtime/models/jetbrains/mps/lang/typesystem2/typechecking.mps
+++ b/typesystem2/languages/jetbrains.mps.lang.typesystem2/runtime/models/jetbrains/mps/lang/typesystem2/typechecking.mps
@@ -6389,8 +6389,8 @@
     <node concept="2tJIrI" id="3GlpCDSyR2$" role="jymVt" />
     <node concept="3clFb_" id="3GlpCDSyRnn" role="jymVt">
       <property role="TrG5h" value="getExpressionSolver" />
-      <node concept="3uibUv" id="3GlpCDSySro" role="3clF45">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2vNhS" role="3clF45">
+        <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
       </node>
       <node concept="3Tm1VV" id="3GlpCDSyRnq" role="1B3o_S" />
       <node concept="3clFbS" id="3GlpCDSyRnr" role="3clF47">
@@ -6429,8 +6429,8 @@
     </node>
     <node concept="312cEg" id="3F6vMxqlTiX" role="jymVt">
       <property role="TrG5h" value="expressionSolver" />
-      <node concept="3uibUv" id="4n$Qn$04BDj" role="1tU5fm">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2vNg1" role="1tU5fm">
+        <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
       </node>
       <node concept="3Tm6S6" id="3GlpCDSyB5p" role="1B3o_S" />
     </node>
diff --git a/typesystem2/solutions/jetbrains.mps.lang.typesystem2.template/models/jetbrains/mps/lang/typesystem2/template.mps b/typesystem2/solutions/jetbrains.mps.lang.typesystem2.template/models/jetbrains/mps/lang/typesystem2/template.mps
index 2636a303..f4505ad3 100644
--- a/typesystem2/solutions/jetbrains.mps.lang.typesystem2.template/models/jetbrains/mps/lang/typesystem2/template.mps
+++ b/typesystem2/solutions/jetbrains.mps.lang.typesystem2.template/models/jetbrains/mps/lang/typesystem2/template.mps
@@ -482,8 +482,8 @@
       <property role="2aFKle" value="false" />
       <node concept="3clFbS" id="1ggxSI7z1S8" role="3clF47" />
       <node concept="3Tm1VV" id="1ggxSI7z1OS" role="1B3o_S" />
-      <node concept="3uibUv" id="1ggxSI7z1Pj" role="3clF45">
-        <ref role="3uigEE" to="w7la:~Queryable" resolve="Queryable" />
+      <node concept="3uibUv" id="5jCHAT2vM0V" role="3clF45">
+        <ref role="3uigEE" to="w7la:~AbstractSolver" resolve="AbstractSolver" />
       </node>
     </node>
     <node concept="2tJIrI" id="4OKkcnfu_xm" role="jymVt" />