diff --git a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/jetbrains.mps.lang.typesystem2.samplechecker.handler.test.msd b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/jetbrains.mps.lang.typesystem2.samplechecker.handler.test.msd
index 2d6ead6e..3e67bd9f 100644
--- a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/jetbrains.mps.lang.typesystem2.samplechecker.handler.test.msd
+++ b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/jetbrains.mps.lang.typesystem2.samplechecker.handler.test.msd
@@ -11,6 +11,8 @@
     <dependency reexport="false">a5478664-6b44-4c62-a9f7-434f8aa57eee(jetbrains.mps.logic.runtime)</dependency>
     <dependency reexport="false">7526e0cf-1ce7-46f8-a555-9eca1e06c23b(jetbrains.mps.logic.atom)</dependency>
     <dependency reexport="false">760652ad-c01a-495e-9510-ed51532f617b(jetbrains.mps.logic.jchr)</dependency>
+    <dependency reexport="true">bbf5c548-7111-4a53-a117-cdefc664cf34(jetbrains.mps.logic.reactor)</dependency>
+    <dependency reexport="false">b189d6c6-9397-4d64-88af-1ac73760a4f5(jetbrains.mps.logic.test)</dependency>
   </dependencies>
   <languageVersions>
     <language id="f3061a53-9226-4cc5-a443-f952ceaf5816" fqName="jetbrains.mps.baseLanguage" version="4" />
@@ -30,6 +32,7 @@
     <module reference="760652ad-c01a-495e-9510-ed51532f617b(jetbrains.mps.logic.jchr)" version="0" />
     <module reference="bbf5c548-7111-4a53-a117-cdefc664cf34(jetbrains.mps.logic.reactor)" version="0" />
     <module reference="a5478664-6b44-4c62-a9f7-434f8aa57eee(jetbrains.mps.logic.runtime)" version="0" />
+    <module reference="b189d6c6-9397-4d64-88af-1ac73760a4f5(jetbrains.mps.logic.test)" version="0" />
   </dependencyVersions>
 </solution>
 
diff --git a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util.mps b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util.mps
index 99d14797..182a5e64 100644
--- a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util.mps
+++ b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.samplechecker.handler.test/models/jetbrains/mps/lang/typesystem2/samplechecker/handle/test/util.mps
@@ -12,11 +12,13 @@
     <import index="4r4j" ref="r:94702bd0-f623-44e8-af0a-f2730f7d2518(jetbrains.mps.lang.typesystem2.samplechecker.handle.util)" />
     <import index="qrld" ref="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)" />
     <import index="95zw" ref="r:f3ff7852-b9dd-4760-b213-a8a031c77d0e(jetbrains.mps.logic.jchr.predicate)" />
+    <import index="rchb" ref="r:f43ee4a0-488a-425a-87a0-594ab3b0d15f(jetbrains.mps.logic.reactor.program)" />
+    <import index="stgg" ref="r:fcdb37a4-4602-4a05-8d91-e439430734b8(jetbrains.mps.logic.jchr.program)" />
+    <import index="mqqo" ref="r:82cec6f7-ddec-440c-961c-1c598267be42(jetbrains.mps.logic.test.unification)" />
   </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="1465982738277781862" name="jetbrains.mps.baseLanguage.structure.PlaceholderMember" flags="ng" index="2tJIrI" />
       <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" />
@@ -24,6 +26,9 @@
       <concept id="1145552977093" name="jetbrains.mps.baseLanguage.structure.GenericNewExpression" flags="nn" index="2ShNRf">
         <child id="1145553007750" name="creator" index="2ShVmc" />
       </concept>
+      <concept id="1137021947720" name="jetbrains.mps.baseLanguage.structure.ConceptFunction" flags="in" index="2VMwT0">
+        <child id="1137022507850" name="body" index="2VODD2" />
+      </concept>
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
@@ -33,9 +38,7 @@
       <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>
@@ -66,9 +69,6 @@
         <child id="1068499141038" name="actualArgument" index="37wK5m" />
       </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">
-        <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" />
       </concept>
@@ -82,7 +82,6 @@
         <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" />
     </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">
@@ -91,6 +90,8 @@
       <concept id="1171931851043" name="jetbrains.mps.baseLanguage.unitTest.structure.BTestCase" flags="ig" index="3s_ewN">
         <property id="1171931851045" name="testCaseName" index="3s_ewP" />
         <child id="1171931851044" name="testMethodList" index="3s_ewO" />
+        <child id="8243879142738613220" name="afterTest" index="1KhZu3" />
+        <child id="8243879142738613219" name="beforeTest" index="1KhZu4" />
       </concept>
       <concept id="1171931858461" name="jetbrains.mps.baseLanguage.unitTest.structure.TestMethodList" flags="ng" index="3s_gsd">
         <child id="1171931858462" name="testMethod" index="3s_gse" />
@@ -98,6 +99,8 @@
       <concept id="1171981022339" name="jetbrains.mps.baseLanguage.unitTest.structure.AssertTrue" flags="nn" index="3vwNmj">
         <child id="1171981057159" name="condition" index="3vwVQn" />
       </concept>
+      <concept id="8243879142738608185" name="jetbrains.mps.baseLanguage.unitTest.structure.BeforeTest" flags="in" index="1KhYhu" />
+      <concept id="8243879142738613213" name="jetbrains.mps.baseLanguage.unitTest.structure.AfterTest" flags="in" index="1KhZuU" />
     </language>
     <language id="35320f26-77cb-4c55-be9f-a97a27770af1" name="jetbrains.mps.logic">
       <concept id="2105510410850132386" name="jetbrains.mps.logic.structure.List" flags="ng" index="KCUsM">
@@ -127,37 +130,6 @@
   </registry>
   <node concept="3s_ewN" id="7t5VLKGALSG">
     <property role="3s_ewP" value="Lub" />
-    <node concept="2tJIrI" id="7t5VLKGALSH" role="jymVt" />
-    <node concept="312cEg" id="7t5VLKGALSI" role="jymVt">
-      <property role="TrG5h" value="uni" />
-      <node concept="3Tm6S6" id="7t5VLKGALSJ" role="1B3o_S" />
-      <node concept="3uibUv" id="7t5VLKGALSK" role="1tU5fm">
-        <ref role="3uigEE" to="95zw:6njqcfQVO0n" resolve="UnificationSolver" />
-      </node>
-      <node concept="2ShNRf" id="7t5VLKGALSL" role="33vP2m">
-        <node concept="1pGfFk" id="7t5VLKGALSM" role="2ShVmc">
-          <ref role="37wK5l" to="95zw:3HJTsBn5KhD" resolve="UnificationSolverImpl" />
-          <node concept="2OqwBi" id="qubcdtu07G" role="37wK5m">
-            <node concept="2YIFZM" id="qubcdttZMi" role="2Oq$k0">
-              <ref role="37wK5l" to="qrld:6Kcfpq7BWKD" resolve="with" />
-              <ref role="1Pybhc" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
-              <node concept="10M0yZ" id="qubcdttZN1" role="37wK5m">
-                <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
-                <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
-              </node>
-              <node concept="10M0yZ" id="qubcdttZN4" role="37wK5m">
-                <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
-                <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
-              </node>
-            </node>
-            <node concept="liA8E" id="qubcdtu0th" role="2OqNvi">
-              <ref role="37wK5l" to="qrld:6Kcfpq7Cgrc" resolve="newSession" />
-            </node>
-          </node>
-          <node concept="10Nm6u" id="5uFPQ7Cmr7o" role="37wK5m" />
-        </node>
-      </node>
-    </node>
     <node concept="3Tm1VV" id="7t5VLKGALSN" role="1B3o_S" />
     <node concept="3s_gsd" id="7t5VLKGALSO" role="3s_ewO">
       <node concept="3s$Bmu" id="7t5VLKGALSP" role="3s_gse">
@@ -367,17 +339,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="4JRKVCv8a6q" role="3cqZAp">
-            <node concept="2OqwBi" id="4JRKVCv8a6r" role="3clFbG">
-              <node concept="37vLTw" id="4JRKVCv8a6s" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_vh_" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_vpp" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_vmP" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_vlo" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_voQ" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4JRKVCv8a6t" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="4JRKVCv8a6u" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_vsV" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_vv8" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_vy4" role="37wK5m">
                   <ref role="3cqZAo" node="4JRKVCv8a6f" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="4JRKVCv8a6v" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_vy5" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALTu" resolve="var" />
                 </node>
               </node>
@@ -606,17 +588,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="7t5VLKGALV7" role="3cqZAp">
-            <node concept="2OqwBi" id="7t5VLKGALV8" role="3clFbG">
-              <node concept="37vLTw" id="7t5VLKGALV9" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_vXh" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_vXi" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_vXj" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_vXk" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_vXl" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="7t5VLKGALVa" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="7t5VLKGALVb" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_vXm" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_vXn" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_vXo" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALUW" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="7t5VLKGALVc" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_vXp" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALUz" resolve="var" />
                 </node>
               </node>
@@ -831,17 +823,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="7t5VLKGALWq" role="3cqZAp">
-            <node concept="2OqwBi" id="7t5VLKGALWr" role="3clFbG">
-              <node concept="37vLTw" id="7t5VLKGALWs" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_wc8" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_wc9" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_wca" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_wcb" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_wcc" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="7t5VLKGALWt" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="7t5VLKGALWu" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_wcd" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_wce" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_wcf" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALWf" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="7t5VLKGALWv" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_wcg" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALVQ" resolve="var" />
                 </node>
               </node>
@@ -1084,17 +1086,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="7t5VLKGALXR" role="3cqZAp">
-            <node concept="2OqwBi" id="7t5VLKGALXS" role="3clFbG">
-              <node concept="37vLTw" id="7t5VLKGALXT" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_w_e" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_w_f" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_w_g" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_w_h" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_w_i" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="7t5VLKGALXU" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="7t5VLKGALXV" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_w_j" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_w_k" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_w_l" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALXG" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="7t5VLKGALXW" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_w_m" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALXj" resolve="var" />
                 </node>
               </node>
@@ -1492,17 +1504,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="7t5VLKGAM00" role="3cqZAp">
-            <node concept="2OqwBi" id="7t5VLKGAM01" role="3clFbG">
-              <node concept="37vLTw" id="7t5VLKGAM02" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_wPq" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_wPr" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_wPs" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_wPt" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_wPu" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="7t5VLKGAM03" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="7t5VLKGAM04" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_wPv" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_wPw" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_wPx" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALZK" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="7t5VLKGAM05" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_wPy" role="37wK5m">
                   <ref role="3cqZAo" node="7t5VLKGALZn" resolve="var" />
                 </node>
               </node>
@@ -1959,17 +1981,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3hfdu5cNgsP" role="3cqZAp">
-            <node concept="2OqwBi" id="3hfdu5cNgsQ" role="3clFbG">
-              <node concept="37vLTw" id="3hfdu5cNgsR" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_x7_" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_x7A" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_x7B" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_x7C" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_x7D" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3hfdu5cNgsS" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3hfdu5cNgsT" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_x7E" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_x7F" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_x7G" role="37wK5m">
                   <ref role="3cqZAo" node="3hfdu5cNgsA" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3hfdu5cNgsU" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_x7H" role="37wK5m">
                   <ref role="3cqZAo" node="3hfdu5cNgsd" resolve="var" />
                 </node>
               </node>
@@ -2483,17 +2515,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3KV3FXk2oK$" role="3cqZAp">
-            <node concept="2OqwBi" id="3KV3FXk2oK_" role="3clFbG">
-              <node concept="37vLTw" id="3KV3FXk2oKA" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_xqP" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_xqQ" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_xqR" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_xqS" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_xqT" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3KV3FXk2oKB" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3KV3FXk2oKC" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_xqU" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_xqV" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_xqW" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk2oKs" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3KV3FXk2oKD" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_xqX" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk2oK3" resolve="var" />
                 </node>
               </node>
@@ -2928,17 +2970,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3hfdu5cN_MZ" role="3cqZAp">
-            <node concept="2OqwBi" id="3hfdu5cN_N0" role="3clFbG">
-              <node concept="37vLTw" id="3hfdu5cN_N1" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_xIi" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_xIj" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_xIk" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_xIl" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_xIm" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3hfdu5cN_N2" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3hfdu5cN_N3" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_xIn" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_xIo" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_xIp" role="37wK5m">
                   <ref role="3cqZAo" node="3hfdu5cN_MP" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3hfdu5cN_N4" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_xIq" role="37wK5m">
                   <ref role="3cqZAo" node="3hfdu5cN_Ms" resolve="var" />
                 </node>
               </node>
@@ -3397,17 +3449,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3KV3FXjXcr$" role="3cqZAp">
-            <node concept="2OqwBi" id="3KV3FXjXcr_" role="3clFbG">
-              <node concept="37vLTw" id="3KV3FXjXcrA" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_y0W" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_y0X" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_y0Y" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_y0Z" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_y10" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3KV3FXjXcrB" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3KV3FXjXcrC" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_y11" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_y12" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_y13" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXjXcrs" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3KV3FXjXcrD" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_y14" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXjXcr3" resolve="var" />
                 </node>
               </node>
@@ -3728,17 +3790,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3KV3FXk18PH" role="3cqZAp">
-            <node concept="2OqwBi" id="3KV3FXk18PI" role="3clFbG">
-              <node concept="37vLTw" id="3KV3FXk18PJ" role="2Oq$k0">
-                <ref role="3cqZAo" node="7t5VLKGALSI" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_yj3" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_yj4" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_yj5" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_yj6" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_yj7" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3KV3FXk18PK" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3KV3FXk18PL" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_yj8" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_yj9" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_yja" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk18Pu" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3KV3FXk18PM" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_yjb" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk18P5" resolve="var" />
                 </node>
               </node>
@@ -3747,39 +3819,54 @@
         </node>
       </node>
     </node>
-  </node>
-  <node concept="3s_ewN" id="3KV3FXk2b2J">
-    <property role="3s_ewP" value="SubtypePath" />
-    <node concept="312cEg" id="3KV3FXk2bd7" role="jymVt">
-      <property role="TrG5h" value="uni" />
-      <node concept="3Tm6S6" id="3KV3FXk2bd8" role="1B3o_S" />
-      <node concept="3uibUv" id="3KV3FXk2bd9" role="1tU5fm">
-        <ref role="3uigEE" to="95zw:6njqcfQVO0n" resolve="UnificationSolver" />
-      </node>
-      <node concept="2ShNRf" id="3KV3FXk2bda" role="33vP2m">
-        <node concept="1pGfFk" id="3KV3FXk2bdb" role="2ShVmc">
-          <ref role="37wK5l" to="95zw:3HJTsBn5KhD" resolve="UnificationSolverImpl" />
-          <node concept="2OqwBi" id="5uFPQ7Cmt4b" role="37wK5m">
-            <node concept="2YIFZM" id="5uFPQ7Cmt4c" role="2Oq$k0">
-              <ref role="37wK5l" to="qrld:6Kcfpq7BWKD" resolve="with" />
-              <ref role="1Pybhc" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
-              <node concept="10M0yZ" id="5uFPQ7Cmt4d" role="37wK5m">
-                <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
-                <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
+    <node concept="1KhYhu" id="5jPBdK_uGO" role="1KhZu4">
+      <node concept="3clFbS" id="5jPBdK_uGP" role="2VODD2">
+        <node concept="3clFbF" id="5jPBdK_uPf" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_uPM" role="3clFbG">
+            <ref role="37wK5l" to="mqqo:7ISVfSIf0j" resolve="init" />
+            <ref role="1Pybhc" to="mqqo:5jPBdK_dIS" resolve="TestingEvaluationSession" />
+          </node>
+        </node>
+        <node concept="3clFbH" id="5jPBdK_uQ_" role="3cqZAp" />
+        <node concept="3clFbF" id="5jPBdK_uRs" role="3cqZAp">
+          <node concept="2OqwBi" id="5jPBdK_uYD" role="3clFbG">
+            <node concept="2OqwBi" id="5jPBdK_uUg" role="2Oq$k0">
+              <node concept="2YIFZM" id="5jPBdK_uTI" role="2Oq$k0">
+                <ref role="37wK5l" to="rchb:7ISVfSIwfH" resolve="newSession" />
+                <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
               </node>
-              <node concept="10M0yZ" id="5uFPQ7Cmt4e" role="37wK5m">
-                <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
-                <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+              <node concept="liA8E" id="5jPBdK_uVI" role="2OqNvi">
+                <ref role="37wK5l" to="rchb:5uFPQ7Bwu9Q" resolve="withPredicates" />
+                <node concept="10M0yZ" id="5jPBdK_uXa" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
+                  <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
+                </node>
+                <node concept="10M0yZ" id="5jPBdK_uXd" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
               </node>
             </node>
-            <node concept="liA8E" id="5uFPQ7Cmt4f" role="2OqNvi">
-              <ref role="37wK5l" to="qrld:6Kcfpq7Cgrc" resolve="newSession" />
+            <node concept="liA8E" id="5jPBdK_v1h" role="2OqNvi">
+              <ref role="37wK5l" to="rchb:7ISVfSIuSh" resolve="start" />
             </node>
           </node>
-          <node concept="10Nm6u" id="5uFPQ7Cmtax" role="37wK5m" />
         </node>
       </node>
     </node>
+    <node concept="1KhZuU" id="5jPBdK_M4W" role="1KhZu3">
+      <node concept="3clFbS" id="5jPBdK_M4X" role="2VODD2">
+        <node concept="3clFbF" id="5jPBdK_M6G" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_M7s" role="3clFbG">
+            <ref role="37wK5l" to="mqqo:5jPBdK_KqB" resolve="deinit" />
+            <ref role="1Pybhc" to="mqqo:5jPBdK_dIS" resolve="TestingEvaluationSession" />
+          </node>
+        </node>
+      </node>
+    </node>
+  </node>
+  <node concept="3s_ewN" id="3KV3FXk2b2J">
+    <property role="3s_ewP" value="SubtypePath" />
     <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">
@@ -4107,17 +4194,27 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="3KV3FXk2bqx" role="3cqZAp">
-            <node concept="2OqwBi" id="3KV3FXk2bqy" role="3clFbG">
-              <node concept="37vLTw" id="3KV3FXk2bqz" role="2Oq$k0">
-                <ref role="3cqZAo" node="3KV3FXk2bd7" resolve="uni" />
+          <node concept="3clFbF" id="5jPBdK_R$R" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_R$S" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_R$T" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_R$U" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_R$V" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3KV3FXk2bq$" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4U_yxogCcGI" resolve="tellUni" />
-                <node concept="37vLTw" id="3KV3FXk2bq_" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_R$W" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_R$X" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdK_R$Y" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk2bqn" resolve="expect" />
                 </node>
-                <node concept="37vLTw" id="3KV3FXk2bqA" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_R$Z" role="37wK5m">
                   <ref role="3cqZAo" node="3KV3FXk2bpY" resolve="var" />
                 </node>
               </node>
@@ -4126,6 +4223,51 @@
         </node>
       </node>
     </node>
+    <node concept="1KhYhu" id="5jPBdK_QIy" role="1KhZu4">
+      <node concept="3clFbS" id="5jPBdK_QIz" role="2VODD2">
+        <node concept="3clFbF" id="5jPBdK_QKi" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_QKj" role="3clFbG">
+            <ref role="37wK5l" to="mqqo:7ISVfSIf0j" resolve="init" />
+            <ref role="1Pybhc" to="mqqo:5jPBdK_dIS" resolve="TestingEvaluationSession" />
+          </node>
+        </node>
+        <node concept="3clFbH" id="5jPBdK_QKk" role="3cqZAp" />
+        <node concept="3clFbF" id="5jPBdK_QKl" role="3cqZAp">
+          <node concept="2OqwBi" id="5jPBdK_QKm" role="3clFbG">
+            <node concept="2OqwBi" id="5jPBdK_QKn" role="2Oq$k0">
+              <node concept="2YIFZM" id="5jPBdK_QKo" role="2Oq$k0">
+                <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                <ref role="37wK5l" to="rchb:7ISVfSIwfH" resolve="newSession" />
+              </node>
+              <node concept="liA8E" id="5jPBdK_QKp" role="2OqNvi">
+                <ref role="37wK5l" to="rchb:5uFPQ7Bwu9Q" resolve="withPredicates" />
+                <node concept="10M0yZ" id="5jPBdK_QKq" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
+                </node>
+                <node concept="10M0yZ" id="5jPBdK_QKr" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+              </node>
+            </node>
+            <node concept="liA8E" id="5jPBdK_QKs" role="2OqNvi">
+              <ref role="37wK5l" to="rchb:7ISVfSIuSh" resolve="start" />
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="1KhZuU" id="5jPBdK_R9y" role="1KhZu3">
+      <node concept="3clFbS" id="5jPBdK_R9z" role="2VODD2">
+        <node concept="3clFbF" id="5jPBdK_RbA" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_RbB" role="3clFbG">
+            <ref role="37wK5l" to="mqqo:5jPBdK_KqB" resolve="deinit" />
+            <ref role="1Pybhc" to="mqqo:5jPBdK_dIS" resolve="TestingEvaluationSession" />
+          </node>
+        </node>
+      </node>
+    </node>
   </node>
 </model>
 
diff --git a/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/predicate.mps b/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/predicate.mps
index 9f7c8e69..b271ace0 100644
--- a/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/predicate.mps
+++ b/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/predicate.mps
@@ -59,6 +59,9 @@
       <concept id="1188220165133" name="jetbrains.mps.baseLanguage.structure.ArrayLiteral" flags="nn" index="2BsdOp">
         <child id="1188220173759" name="item" index="2BsfMF" />
       </concept>
+      <concept id="2820489544401957797" name="jetbrains.mps.baseLanguage.structure.DefaultClassCreator" flags="nn" index="HV5vD">
+        <reference id="2820489544401957798" name="classifier" index="HV5vE" />
+      </concept>
       <concept id="1224848483129" name="jetbrains.mps.baseLanguage.structure.IBLDeprecatable" flags="ng" index="IEa8$">
         <property id="1224848525476" name="isDeprecated" index="IEkAT" />
       </concept>
@@ -8482,5 +8485,441 @@
       </node>
     </node>
   </node>
+  <node concept="312cEu" id="7ISVfSIxNO">
+    <property role="2bfB8j" value="false" />
+    <property role="TrG5h" value="Symbols" />
+    <node concept="2tJIrI" id="7ISVfSIy3T" role="jymVt" />
+    <node concept="3clFbW" id="5mr7UHch7og" role="jymVt">
+      <node concept="3cqZAl" id="5mr7UHch7oi" role="3clF45" />
+      <node concept="3Tm1VV" id="5mr7UHch7oj" role="1B3o_S" />
+      <node concept="3clFbS" id="5mr7UHch7ok" role="3clF47">
+        <node concept="3clFbF" id="5mr7UHch7DZ" role="3cqZAp">
+          <node concept="37vLTI" id="5mr7UHch7E1" role="3clFbG">
+            <node concept="2OqwBi" id="5mr7UHch7E5" role="37vLTJ">
+              <node concept="Xjq3P" id="5mr7UHch7E8" role="2Oq$k0" />
+              <node concept="2OwXpG" id="5mr7UHch9IB" role="2OqNvi">
+                <ref role="2Oxat5" node="5mr7UHch7DV" resolve="computingSession" />
+              </node>
+            </node>
+            <node concept="37vLTw" id="5mr7UHch7E9" role="37vLTx">
+              <ref role="3cqZAo" node="5mr7UHch7vp" resolve="computingSession" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="5mr7UHchbUd" role="3cqZAp">
+          <node concept="37vLTI" id="5mr7UHchbUf" role="3clFbG">
+            <node concept="2OqwBi" id="5mr7UHchbUj" role="37vLTJ">
+              <node concept="Xjq3P" id="5mr7UHchbUm" role="2Oq$k0" />
+              <node concept="2OwXpG" id="5mr7UHchbUi" role="2OqNvi">
+                <ref role="2Oxat5" node="5mr7UHchbU9" resolve="computingTracer" />
+              </node>
+            </node>
+            <node concept="37vLTw" id="5mr7UHchbUn" role="37vLTx">
+              <ref role="3cqZAo" node="5mr7UHchb$f" resolve="computingTracer" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="37vLTG" id="5mr7UHch7vp" role="3clF46">
+        <property role="TrG5h" value="computingSession" />
+        <node concept="3uibUv" id="5mr7UHch7vo" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="5mr7UHchb$f" role="3clF46">
+        <property role="TrG5h" value="computingTracer" />
+        <node concept="3uibUv" id="5mr7UHchbC8" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5mr7UHch7zp" role="jymVt" />
+    <node concept="3clFb_" id="5jPBdK__lx" role="jymVt">
+      <property role="TrG5h" value="registerSymbols" />
+      <node concept="37vLTG" id="5jPBdK_Ahj" role="3clF46">
+        <property role="TrG5h" value="predicateSymbols" />
+        <node concept="8X2XB" id="5jPBdK_AnW" role="1tU5fm">
+          <node concept="3uibUv" id="5jPBdK_Anu" role="8Xvag">
+            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="5jPBdK__lz" role="3clF45" />
+      <node concept="3Tm1VV" id="5jPBdK__l$" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK__l_" role="3clF47">
+        <node concept="1DcWWT" id="5mr7UHchfPx" role="3cqZAp">
+          <node concept="3clFbS" id="5mr7UHchfPz" role="2LFqv$">
+            <node concept="3clFbF" id="5jPBdK_AI8" role="3cqZAp">
+              <node concept="1rXfSq" id="5jPBdK_AI6" role="3clFbG">
+                <ref role="37wK5l" node="7ISVfSIy6a" resolve="register" />
+                <node concept="37vLTw" id="5jPBdK_AJz" role="37wK5m">
+                  <ref role="3cqZAo" node="5mr7UHchfP_" resolve="symbol" />
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3cpWsn" id="5mr7UHchfP_" role="1Duv9x">
+            <property role="TrG5h" value="symbol" />
+            <node concept="3uibUv" id="5mr7UHchfPD" role="1tU5fm">
+              <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+            </node>
+          </node>
+          <node concept="37vLTw" id="5jPBdK_AEg" role="1DdaDG">
+            <ref role="3cqZAo" node="5jPBdK_Ahj" resolve="predicateSymbols" />
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK__cB" role="jymVt" />
+    <node concept="3clFb_" id="7ISVfSIy6a" role="jymVt">
+      <property role="TrG5h" value="register" />
+      <node concept="37vLTG" id="7ISVfSIJee" role="3clF46">
+        <property role="TrG5h" value="symbol" />
+        <node concept="3uibUv" id="7ISVfSIJhR" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:5uFPQ7B$mzX" resolve="Symbol" />
+        </node>
+      </node>
+      <node concept="3cqZAl" id="7ISVfSIy6c" role="3clF45" />
+      <node concept="3Tmbuc" id="5mr7UHchdZc" role="1B3o_S" />
+      <node concept="3clFbS" id="7ISVfSIy6e" role="3clF47">
+        <node concept="3clFbH" id="7ISVfSIYKv" role="3cqZAp" />
+        <node concept="3clFbJ" id="7ISVfSIIXN" role="3cqZAp">
+          <node concept="3clFbS" id="7ISVfSIIXO" role="3clFbx">
+            <node concept="3clFbF" id="7ISVfSIVrg" role="3cqZAp">
+              <node concept="2OqwBi" id="7ISVfSIVrQ" role="3clFbG">
+                <node concept="37vLTw" id="7ISVfSIVrf" role="2Oq$k0">
+                  <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                </node>
+                <node concept="liA8E" id="7ISVfSIVsU" role="2OqNvi">
+                  <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+                  <node concept="10QFUN" id="7ISVfSIYFl" role="37wK5m">
+                    <node concept="3uibUv" id="7ISVfSIYFj" role="10QFUM">
+                      <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+                    </node>
+                    <node concept="37vLTw" id="7ISVfSIYFk" role="10QFUP">
+                      <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                    </node>
+                  </node>
+                  <node concept="2ShNRf" id="7ISVfSIVIp" role="37wK5m">
+                    <node concept="1pGfFk" id="7ISVfSIWk9" role="2ShVmc">
+                      <ref role="37wK5l" node="3HJTsBn5KhD" resolve="UnificationSolverImpl" />
+                      <node concept="37vLTw" id="5mr7UHchbwX" role="37wK5m">
+                        <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                      </node>
+                      <node concept="37vLTw" id="5mr7UHchcsc" role="37wK5m">
+                        <ref role="3cqZAo" node="5mr7UHchbU9" resolve="computingTracer" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+            </node>
+            <node concept="3clFbH" id="7ISVfSIYJ8" role="3cqZAp" />
+          </node>
+          <node concept="2OqwBi" id="7ISVfSIJwN" role="3clFbw">
+            <node concept="10M0yZ" id="7ISVfSIJ9U" role="2Oq$k0">
+              <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+              <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+            </node>
+            <node concept="liA8E" id="7ISVfSIJyd" role="2OqNvi">
+              <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
+              <node concept="37vLTw" id="7ISVfSIJzc" role="37wK5m">
+                <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+              </node>
+            </node>
+          </node>
+          <node concept="3eNFk2" id="7ISVfSIJml" role="3eNLev">
+            <node concept="2OqwBi" id="7ISVfSIJ_2" role="3eO9$A">
+              <node concept="10M0yZ" id="7ISVfSIJrd" role="2Oq$k0">
+                <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
+                <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
+              </node>
+              <node concept="liA8E" id="7ISVfSIJAs" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
+                <node concept="37vLTw" id="7ISVfSIJBV" role="37wK5m">
+                  <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                </node>
+              </node>
+            </node>
+            <node concept="3clFbS" id="7ISVfSIJmn" role="3eOfB_">
+              <node concept="3clFbF" id="7ISVfSIYOv" role="3cqZAp">
+                <node concept="2OqwBi" id="7ISVfSIYOw" role="3clFbG">
+                  <node concept="37vLTw" id="7ISVfSIYOx" role="2Oq$k0">
+                    <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                  </node>
+                  <node concept="liA8E" id="7ISVfSIYOy" role="2OqNvi">
+                    <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+                    <node concept="10QFUN" id="7ISVfSIYOz" role="37wK5m">
+                      <node concept="3uibUv" id="7ISVfSIYO$" role="10QFUM">
+                        <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+                      </node>
+                      <node concept="37vLTw" id="7ISVfSIYO_" role="10QFUP">
+                        <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                      </node>
+                    </node>
+                    <node concept="2ShNRf" id="7ISVfSIYOA" role="37wK5m">
+                      <node concept="1pGfFk" id="7ISVfSIYOB" role="2ShVmc">
+                        <ref role="37wK5l" node="3HJTsBn5dl7" resolve="EqualsSolverImpl" />
+                        <node concept="37vLTw" id="7ISVfSIYOD" role="37wK5m">
+                          <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                        </node>
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbH" id="7ISVfSIYSU" role="3cqZAp" />
+            </node>
+          </node>
+          <node concept="3eNFk2" id="7ISVfSIJuG" role="3eNLev">
+            <node concept="2OqwBi" id="7ISVfSIJGK" role="3eO9$A">
+              <node concept="10M0yZ" id="7ISVfSIJCI" role="2Oq$k0">
+                <ref role="1PxDUh" to="oy3s:6infEALAfer" resolve="AssertBuiltinConstraint" />
+                <ref role="3cqZAo" to="oy3s:5uFPQ7BZnLB" resolve="ASSERT_SYM" />
+              </node>
+              <node concept="liA8E" id="7ISVfSIJIa" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
+                <node concept="37vLTw" id="7ISVfSIJJb" role="37wK5m">
+                  <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                </node>
+              </node>
+            </node>
+            <node concept="3clFbS" id="7ISVfSIJuI" role="3eOfB_">
+              <node concept="3clFbF" id="7ISVfSIZhm" role="3cqZAp">
+                <node concept="2OqwBi" id="7ISVfSIZhn" role="3clFbG">
+                  <node concept="37vLTw" id="7ISVfSIZho" role="2Oq$k0">
+                    <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                  </node>
+                  <node concept="liA8E" id="7ISVfSIZhp" role="2OqNvi">
+                    <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+                    <node concept="10QFUN" id="7ISVfSIZhq" role="37wK5m">
+                      <node concept="3uibUv" id="7ISVfSIZhr" role="10QFUM">
+                        <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+                      </node>
+                      <node concept="37vLTw" id="7ISVfSIZhs" role="10QFUP">
+                        <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                      </node>
+                    </node>
+                    <node concept="2ShNRf" id="7ISVfSIZht" role="37wK5m">
+                      <node concept="1pGfFk" id="7ISVfSIZhu" role="2ShVmc">
+                        <ref role="37wK5l" node="6infEALANZc" resolve="AssertSolverImpl" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbH" id="7ISVfSIZlS" role="3cqZAp" />
+            </node>
+          </node>
+          <node concept="3eNFk2" id="7ISVfSIJJE" role="3eNLev">
+            <node concept="2OqwBi" id="7ISVfSIJJF" role="3eO9$A">
+              <node concept="10M0yZ" id="7ISVfSIK8M" role="2Oq$k0">
+                <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
+                <ref role="3cqZAo" to="xq5w:5uFPQ7C26$b" resolve="BOUND_SYM" />
+              </node>
+              <node concept="liA8E" id="7ISVfSIJJH" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
+                <node concept="37vLTw" id="7ISVfSIJJI" role="37wK5m">
+                  <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                </node>
+              </node>
+            </node>
+            <node concept="3clFbS" id="7ISVfSIJJJ" role="3eOfB_">
+              <node concept="3clFbF" id="7ISVfSJ2P6" role="3cqZAp">
+                <node concept="2OqwBi" id="7ISVfSJ2P7" role="3clFbG">
+                  <node concept="37vLTw" id="7ISVfSJ2P8" role="2Oq$k0">
+                    <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                  </node>
+                  <node concept="liA8E" id="7ISVfSJ2P9" role="2OqNvi">
+                    <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+                    <node concept="10QFUN" id="7ISVfSJ2Pa" role="37wK5m">
+                      <node concept="3uibUv" id="7ISVfSJ2Pb" role="10QFUM">
+                        <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+                      </node>
+                      <node concept="37vLTw" id="7ISVfSJ2Pc" role="10QFUP">
+                        <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                      </node>
+                    </node>
+                    <node concept="2ShNRf" id="7ISVfSJ2Pd" role="37wK5m">
+                      <node concept="HV5vD" id="7ISVfSJ2Zy" role="2ShVmc">
+                        <ref role="HV5vE" node="7ISVfSJ0DF" resolve="LogicalSolverImpl.Bound" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbH" id="7ISVfSJ2Np" role="3cqZAp" />
+            </node>
+          </node>
+          <node concept="3eNFk2" id="7ISVfSJ2Gd" role="3eNLev">
+            <node concept="2OqwBi" id="7ISVfSJ2Ge" role="3eO9$A">
+              <node concept="10M0yZ" id="7ISVfSJ2Gf" role="2Oq$k0">
+                <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
+                <ref role="3cqZAo" to="xq5w:5uFPQ7C279$" resolve="FREE_SYM" />
+              </node>
+              <node concept="liA8E" id="7ISVfSJ2Gg" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
+                <node concept="37vLTw" id="7ISVfSJ2Gh" role="37wK5m">
+                  <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                </node>
+              </node>
+            </node>
+            <node concept="3clFbS" id="7ISVfSJ2Gi" role="3eOfB_">
+              <node concept="3clFbF" id="7ISVfSJ30n" role="3cqZAp">
+                <node concept="2OqwBi" id="7ISVfSJ30o" role="3clFbG">
+                  <node concept="37vLTw" id="7ISVfSJ30p" role="2Oq$k0">
+                    <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+                  </node>
+                  <node concept="liA8E" id="7ISVfSJ30q" role="2OqNvi">
+                    <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+                    <node concept="10QFUN" id="7ISVfSJ30r" role="37wK5m">
+                      <node concept="3uibUv" id="7ISVfSJ30s" role="10QFUM">
+                        <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+                      </node>
+                      <node concept="37vLTw" id="7ISVfSJ30t" role="10QFUP">
+                        <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                      </node>
+                    </node>
+                    <node concept="2ShNRf" id="7ISVfSJ30u" role="37wK5m">
+                      <node concept="HV5vD" id="7ISVfSJ3cx" role="2ShVmc">
+                        <ref role="HV5vE" node="7ISVfSJ1oi" resolve="LogicalSolverImpl.Free" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+              <node concept="3clFbH" id="7ISVfSJ2Nu" role="3cqZAp" />
+            </node>
+          </node>
+          <node concept="9aQIb" id="5mr7UHchgcy" role="9aQIa">
+            <node concept="3clFbS" id="5mr7UHchgcz" role="9aQI4">
+              <node concept="YS8fn" id="5mr7UHchgjZ" role="3cqZAp">
+                <node concept="2ShNRf" id="5mr7UHchgme" role="YScLw">
+                  <node concept="1pGfFk" id="5mr7UHchgDA" role="2ShVmc">
+                    <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;(java.lang.String)" resolve="IllegalArgumentException" />
+                    <node concept="3cpWs3" id="5mr7UHchgIt" role="37wK5m">
+                      <node concept="37vLTw" id="5mr7UHchgKN" role="3uHU7w">
+                        <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
+                      </node>
+                      <node concept="Xl_RD" id="5mr7UHchgEB" role="3uHU7B">
+                        <property role="Xl_RC" value="unknown symbol: " />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbH" id="5mr7UHcbFmH" role="3cqZAp" />
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5mr7UHch7aO" role="jymVt" />
+    <node concept="3clFb_" id="6Kcfpq7Bs88" role="jymVt">
+      <property role="TrG5h" value="registerHandler" />
+      <node concept="37vLTG" id="7ISVfSIOyP" role="3clF46">
+        <property role="TrG5h" value="symbol" />
+        <node concept="3uibUv" id="7ISVfSIOGX" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:5uFPQ7B$mzX" resolve="Symbol" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="6Kcfpq7BtOW" role="3clF46">
+        <property role="TrG5h" value="instructible" />
+        <node concept="3uibUv" id="6Kcfpq7BtZc" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:6Kcfpq7AXVG" resolve="Instructible" />
+        </node>
+      </node>
+      <node concept="3cqZAl" id="6Kcfpq7Bs8a" role="3clF45" />
+      <node concept="3Tmbuc" id="6Kcfpq7BskN" role="1B3o_S" />
+      <node concept="3clFbS" id="6Kcfpq7Bs8c" role="3clF47">
+        <node concept="3clFbF" id="6Kcfpq7Bu1B" role="3cqZAp">
+          <node concept="2OqwBi" id="6Kcfpq7Bu22" role="3clFbG">
+            <node concept="37vLTw" id="7ISVfSIOWI" role="2Oq$k0">
+              <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+            </node>
+            <node concept="liA8E" id="6Kcfpq7Bu2G" role="2OqNvi">
+              <ref role="37wK5l" to="qrld:6Kcfpq7B2yH" resolve="registerHandler" />
+              <node concept="37vLTw" id="7ISVfSIOLP" role="37wK5m">
+                <ref role="3cqZAo" node="7ISVfSIOyP" resolve="symbol" />
+              </node>
+              <node concept="37vLTw" id="6Kcfpq7Bu3W" role="37wK5m">
+                <ref role="3cqZAo" node="6Kcfpq7BtOW" resolve="instructible" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="6Kcfpq7BuLv" role="jymVt" />
+    <node concept="3clFb_" id="6Kcfpq7Buzk" role="jymVt">
+      <property role="TrG5h" value="registerSolver" />
+      <node concept="37vLTG" id="7ISVfSIOZm" role="3clF46">
+        <property role="TrG5h" value="predicateSymbol" />
+        <node concept="3uibUv" id="7ISVfSIPw0" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="6Kcfpq7Buzn" role="3clF46">
+        <property role="TrG5h" value="queryable" />
+        <node concept="3uibUv" id="6Kcfpq7Bw2C" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:6Kcfpq7AYBh" resolve="Queryable" />
+        </node>
+      </node>
+      <node concept="3cqZAl" id="6Kcfpq7Buzp" role="3clF45" />
+      <node concept="3Tmbuc" id="6Kcfpq7Buzq" role="1B3o_S" />
+      <node concept="3clFbS" id="6Kcfpq7Buzr" role="3clF47">
+        <node concept="3clFbF" id="6Kcfpq7Buzs" role="3cqZAp">
+          <node concept="2OqwBi" id="6Kcfpq7Buzt" role="3clFbG">
+            <node concept="37vLTw" id="7ISVfSIPqq" role="2Oq$k0">
+              <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+            </node>
+            <node concept="liA8E" id="6Kcfpq7Buzv" role="2OqNvi">
+              <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
+              <node concept="37vLTw" id="7ISVfSIPef" role="37wK5m">
+                <ref role="3cqZAo" node="7ISVfSIOZm" resolve="predicateSymbol" />
+              </node>
+              <node concept="37vLTw" id="6Kcfpq7Buzx" role="37wK5m">
+                <ref role="3cqZAo" node="6Kcfpq7Buzn" resolve="queryable" />
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="4xBopTzylBh" role="3cqZAp">
+          <node concept="2OqwBi" id="4xBopTzylBi" role="3clFbG">
+            <node concept="37vLTw" id="7ISVfSIPtf" role="2Oq$k0">
+              <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
+            </node>
+            <node concept="liA8E" id="4xBopTzylBk" role="2OqNvi">
+              <ref role="37wK5l" to="qrld:6Kcfpq7B2yH" resolve="registerHandler" />
+              <node concept="37vLTw" id="7ISVfSIPfC" role="37wK5m">
+                <ref role="3cqZAo" node="7ISVfSIOZm" resolve="predicateSymbol" />
+              </node>
+              <node concept="37vLTw" id="4xBopTzylH0" role="37wK5m">
+                <ref role="3cqZAo" node="6Kcfpq7Buzn" resolve="queryable" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5uFPQ7BZbUe" role="jymVt" />
+    <node concept="2tJIrI" id="7ISVfSIy3Y" role="jymVt" />
+    <node concept="3Tm1VV" id="5jPBdK_$TM" role="1B3o_S" />
+    <node concept="312cEg" id="5mr7UHch7DV" role="jymVt">
+      <property role="TrG5h" value="computingSession" />
+      <node concept="3Tm6S6" id="5mr7UHch7DW" role="1B3o_S" />
+      <node concept="3uibUv" id="5mr7UHch7DY" role="1tU5fm">
+        <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5mr7UHchpFD" role="jymVt" />
+    <node concept="312cEg" id="5mr7UHchbU9" role="jymVt">
+      <property role="TrG5h" value="computingTracer" />
+      <node concept="3Tm6S6" id="5mr7UHchbUa" role="1B3o_S" />
+      <node concept="3uibUv" id="5mr7UHchbUc" role="1tU5fm">
+        <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
+      </node>
+    </node>
+  </node>
 </model>
 
diff --git a/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/program.mps b/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/program.mps
index 76e2f48b..ad6496bf 100644
--- a/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/program.mps
+++ b/languages/jetbrains.mps.logic/jchr/models/jetbrains/mps/logic/jchr/program.mps
@@ -33,9 +33,6 @@
       <concept id="1219920932475" name="jetbrains.mps.baseLanguage.structure.VariableArityType" flags="in" index="8X2XB">
         <child id="1219921048460" name="componentType" index="8Xvag" />
       </concept>
-      <concept id="1082485599095" name="jetbrains.mps.baseLanguage.structure.BlockStatement" flags="nn" index="9aQIb">
-        <child id="1082485599096" name="statements" index="9aQI4" />
-      </concept>
       <concept id="1215693861676" name="jetbrains.mps.baseLanguage.structure.BaseAssignmentExpression" flags="nn" index="d038R">
         <child id="1068498886297" name="rValue" index="37vLTx" />
         <child id="1068498886295" name="lValue" index="37vLTJ" />
@@ -142,10 +139,8 @@
       </concept>
       <concept id="1068580123157" name="jetbrains.mps.baseLanguage.structure.Statement" flags="nn" index="3clFbH" />
       <concept id="1068580123159" name="jetbrains.mps.baseLanguage.structure.IfStatement" flags="nn" index="3clFbJ">
-        <child id="1082485599094" name="ifFalseStatement" index="9aQIa" />
         <child id="1068580123160" name="condition" index="3clFbw" />
         <child id="1068580123161" name="ifTrue" index="3clFbx" />
-        <child id="1206060520071" name="elsifClauses" index="3eNLev" />
       </concept>
       <concept id="1068580123136" name="jetbrains.mps.baseLanguage.structure.StatementList" flags="sn" stub="5293379017992965193" index="3clFbS">
         <child id="1068581517665" name="statement" index="3cqZAp" />
@@ -163,10 +158,6 @@
       </concept>
       <concept id="1068581242863" name="jetbrains.mps.baseLanguage.structure.LocalVariableDeclaration" flags="nr" index="3cpWsn" />
       <concept id="1068581517677" name="jetbrains.mps.baseLanguage.structure.VoidType" flags="in" index="3cqZAl" />
-      <concept id="1206060495898" name="jetbrains.mps.baseLanguage.structure.ElsifClause" flags="ng" index="3eNFk2">
-        <child id="1206060619838" name="condition" index="3eO9$A" />
-        <child id="1206060644605" name="statementList" index="3eOfB_" />
-      </concept>
       <concept id="1081506773034" name="jetbrains.mps.baseLanguage.structure.LessThanExpression" flags="nn" index="3eOVzh" />
       <concept id="1204053956946" name="jetbrains.mps.baseLanguage.structure.IMethodCall" flags="ng" index="1ndlxa">
         <reference id="1068499141037" name="baseMethodDeclaration" index="37wK5l" />
@@ -292,8 +283,8 @@
                   <node concept="37vLTw" id="7ISVfSIkA9" role="2Oq$k0">
                     <ref role="3cqZAo" node="7ISVfSIeK_" resolve="config" />
                   </node>
-                  <node concept="liA8E" id="7ISVfSIkAa" role="2OqNvi">
-                    <ref role="37wK5l" node="7ISVfSIiZn" resolve="getPredicateSymbols" />
+                  <node concept="2OwXpG" id="5jPBdK_kJY" role="2OqNvi">
+                    <ref role="2Oxat5" node="7ISVfSIioQ" resolve="predicateSymbols" />
                   </node>
                 </node>
               </node>
@@ -304,62 +295,38 @@
           </node>
         </node>
         <node concept="3clFbH" id="5mr7UHchezJ" role="3cqZAp" />
-        <node concept="3cpWs8" id="5mr7UHcheHc" role="3cqZAp">
-          <node concept="3cpWsn" id="5mr7UHcheHd" role="3cpWs9">
-            <property role="TrG5h" value="symbols" />
-            <node concept="3uibUv" id="5mr7UHcheGS" role="1tU5fm">
-              <ref role="3uigEE" node="7ISVfSIxNO" resolve="JchrEvaluationSession.Symbols" />
-            </node>
-            <node concept="2ShNRf" id="5mr7UHcheHe" role="33vP2m">
-              <node concept="1pGfFk" id="5mr7UHcheHf" role="2ShVmc">
-                <ref role="37wK5l" node="5mr7UHch7og" resolve="JchrEvaluationSession.Symbols" />
-                <node concept="37vLTw" id="5mr7UHcheHg" role="37wK5m">
+        <node concept="3clFbF" id="5jPBdK_B63" role="3cqZAp">
+          <node concept="2OqwBi" id="5jPBdK_Bcd" role="3clFbG">
+            <node concept="2ShNRf" id="5jPBdK_BqZ" role="2Oq$k0">
+              <node concept="1pGfFk" id="5jPBdK_Br0" role="2ShVmc">
+                <ref role="37wK5l" to="95zw:5mr7UHch7og" resolve="Symbols" />
+                <node concept="37vLTw" id="5jPBdK_Br1" role="37wK5m">
                   <ref role="3cqZAo" node="7ISVfSIkA5" resolve="csession" />
                 </node>
-                <node concept="2OqwBi" id="5mr7UHcheHh" role="37wK5m">
-                  <node concept="37vLTw" id="5mr7UHcheHi" role="2Oq$k0">
+                <node concept="2OqwBi" id="5jPBdK_Br2" role="37wK5m">
+                  <node concept="37vLTw" id="5jPBdK_Br3" role="2Oq$k0">
                     <ref role="3cqZAo" node="7ISVfSIeK_" resolve="config" />
                   </node>
-                  <node concept="liA8E" id="5mr7UHcheHj" role="2OqNvi">
-                    <ref role="37wK5l" node="5mr7UHcbx7o" resolve="getComputingTracer" />
+                  <node concept="2OwXpG" id="5jPBdK_Br4" role="2OqNvi">
+                    <ref role="2Oxat5" node="5mr7UHcbs2A" resolve="computingTracer" />
                   </node>
                 </node>
               </node>
             </node>
+            <node concept="liA8E" id="5jPBdK_Bhd" role="2OqNvi">
+              <ref role="37wK5l" to="95zw:5jPBdK__lx" resolve="registerSymbols" />
+              <node concept="2OqwBi" id="5jPBdK_Bie" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdK_Bif" role="2Oq$k0">
+                  <ref role="3cqZAo" node="7ISVfSIeK_" resolve="config" />
+                </node>
+                <node concept="2OwXpG" id="5jPBdK_Big" role="2OqNvi">
+                  <ref role="2Oxat5" node="7ISVfSIioQ" resolve="predicateSymbols" />
+                </node>
+              </node>
+            </node>
           </node>
         </node>
-        <node concept="1DcWWT" id="5mr7UHchfPx" role="3cqZAp">
-          <node concept="3clFbS" id="5mr7UHchfPz" role="2LFqv$">
-            <node concept="3clFbF" id="5mr7UHchebU" role="3cqZAp">
-              <node concept="2OqwBi" id="5mr7UHchg4S" role="3clFbG">
-                <node concept="37vLTw" id="5mr7UHcheHk" role="2Oq$k0">
-                  <ref role="3cqZAo" node="5mr7UHcheHd" resolve="symbols" />
-                </node>
-                <node concept="liA8E" id="5mr7UHchgaR" role="2OqNvi">
-                  <ref role="37wK5l" node="7ISVfSIy6a" resolve="register" />
-                  <node concept="37vLTw" id="5mr7UHchgbS" role="37wK5m">
-                    <ref role="3cqZAo" node="5mr7UHchfP_" resolve="symbol" />
-                  </node>
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3cpWsn" id="5mr7UHchfP_" role="1Duv9x">
-            <property role="TrG5h" value="symbol" />
-            <node concept="3uibUv" id="5mr7UHchfPD" role="1tU5fm">
-              <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-            </node>
-          </node>
-          <node concept="2OqwBi" id="5mr7UHchfPE" role="1DdaDG">
-            <node concept="37vLTw" id="5mr7UHchfPF" role="2Oq$k0">
-              <ref role="3cqZAo" node="7ISVfSIeK_" resolve="config" />
-            </node>
-            <node concept="liA8E" id="5mr7UHchfPG" role="2OqNvi">
-              <ref role="37wK5l" node="7ISVfSIiZn" resolve="getPredicateSymbols" />
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbH" id="5mr7UHch5Ht" role="3cqZAp" />
+        <node concept="3clFbH" id="5jPBdK_Byj" role="3cqZAp" />
         <node concept="3clFbF" id="7ISVfSIeOH" role="3cqZAp">
           <node concept="2ShNRf" id="7ISVfSIeOF" role="3clFbG">
             <node concept="1pGfFk" id="7ISVfSIeUk" role="2ShVmc">
@@ -472,90 +439,6 @@
       </node>
     </node>
     <node concept="2tJIrI" id="7ISVfSIhAc" role="jymVt" />
-    <node concept="3clFb_" id="7ISVfSIg2G" role="jymVt">
-      <property role="TrG5h" value="tell" />
-      <property role="1EzhhJ" value="false" />
-      <node concept="3cqZAl" id="7ISVfSIg2H" role="3clF45" />
-      <node concept="3Tm1VV" id="7ISVfSIg2I" role="1B3o_S" />
-      <node concept="37vLTG" id="7ISVfSIg2K" role="3clF46">
-        <property role="TrG5h" value="symbol" />
-        <node concept="3uibUv" id="7ISVfSIqv7" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:5uFPQ7B$mzX" resolve="Symbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="7ISVfSIg2M" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="7ISVfSIg2N" role="1tU5fm">
-          <node concept="3uibUv" id="7ISVfSIg2O" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-      <node concept="3clFbS" id="7ISVfSIg2P" role="3clF47">
-        <node concept="3clFbF" id="7ISVfSIob6" role="3cqZAp">
-          <node concept="2OqwBi" id="7ISVfSIobF" role="3clFbG">
-            <node concept="37vLTw" id="7ISVfSIob5" role="2Oq$k0">
-              <ref role="3cqZAo" node="7ISVfSIlkQ" resolve="computingSession" />
-            </node>
-            <node concept="liA8E" id="7ISVfSIofH" role="2OqNvi">
-              <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
-              <node concept="37vLTw" id="7ISVfSIora" role="37wK5m">
-                <ref role="3cqZAo" node="7ISVfSIg2K" resolve="symbol" />
-              </node>
-              <node concept="37vLTw" id="7ISVfSIomK" role="37wK5m">
-                <ref role="3cqZAo" node="7ISVfSIg2M" resolve="args" />
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="7ISVfSIqVs" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
-    <node concept="2tJIrI" id="7ISVfSIhI1" role="jymVt" />
-    <node concept="3clFb_" id="7ISVfSIg30" role="jymVt">
-      <property role="TrG5h" value="ask" />
-      <property role="1EzhhJ" value="false" />
-      <node concept="3cqZAl" id="7ISVfSIg31" role="3clF45" />
-      <node concept="3Tm1VV" id="7ISVfSIg32" role="1B3o_S" />
-      <node concept="37vLTG" id="7ISVfSIg34" role="3clF46">
-        <property role="TrG5h" value="predicateSymbol" />
-        <node concept="3uibUv" id="7ISVfSIg35" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="7ISVfSIrPy" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="7ISVfSIs2D" role="1tU5fm">
-          <node concept="3uibUv" id="7ISVfSIrW_" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-      <node concept="3clFbS" id="7ISVfSIg36" role="3clF47">
-        <node concept="3clFbF" id="7ISVfSIrIB" role="3cqZAp">
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-            <node concept="37vLTw" id="7ISVfSIrIA" role="2Oq$k0">
-              <ref role="3cqZAo" node="7ISVfSIlkQ" resolve="computingSession" />
-            </node>
-            <node concept="liA8E" id="7ISVfSIrMb" role="2OqNvi">
-              <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
-              <node concept="37vLTw" id="7ISVfSIrMZ" role="37wK5m">
-                <ref role="3cqZAo" node="7ISVfSIg34" resolve="predicateSymbol" />
-              </node>
-              <node concept="37vLTw" id="7ISVfSIswq" role="37wK5m">
-                <ref role="3cqZAo" node="7ISVfSIrPy" resolve="args" />
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2AHcQZ" id="7ISVfSIri5" role="2AJF6D">
-        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
-      </node>
-    </node>
-    <node concept="2tJIrI" id="7ISVfSIhXI" role="jymVt" />
     <node concept="3clFb_" id="7ISVfSIg37" role="jymVt">
       <property role="TrG5h" value="constraintSymbols" />
       <property role="1EzhhJ" value="false" />
@@ -896,64 +779,155 @@
           </node>
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-      <node concept="3clFb_" id="7ISVfSIiZn" role="jymVt">
-        <property role="TrG5h" value="getPredicateSymbols" />
-        <node concept="10Q1$e" id="5mr7UHchhag" role="3clF45">
-          <node concept="3uibUv" id="5mr7UHchgVU" role="10Q1$1">
-            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+      <node concept="2tJIrI" id="5jPBdK_iKa" role="jymVt" />
+      <node concept="3clFb_" id="5uFPQ7Bwu9Q" role="jymVt">
+        <property role="TrG5h" value="withPredicates" />
+        <node concept="37vLTG" id="5uFPQ7BwufO" role="3clF46">
+          <property role="TrG5h" value="predicateSymbols" />
+          <node concept="8X2XB" id="5uFPQ7BwuhP" role="1tU5fm">
+            <node concept="3uibUv" id="5uFPQ7BZb0v" role="8Xvag">
+              <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+            </node>
           </node>
         </node>
-        <node concept="3Tmbuc" id="5mr7UHcbwKC" role="1B3o_S" />
-        <node concept="3clFbS" id="7ISVfSIiZr" role="3clF47">
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-            <node concept="2YIFZM" id="5mr7UHchfIK" role="3clFbG">
-              <ref role="37wK5l" to="33ny:~Arrays.asList(java.lang.Object...):java.util.List" resolve="asList" />
-              <ref role="1Pybhc" to="33ny:~Arrays" resolve="Arrays" />
-              <node concept="37vLTw" id="5mr7UHchfKW" role="37wK5m">
-                <ref role="3cqZAo" to="rchb:7ISVfSIioQ" resolve="predicateSymbols" />
+        <node concept="3uibUv" id="5uFPQ7Bwub9" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5uFPQ7Bwu9T" role="1B3o_S" />
+        <node concept="3clFbS" id="5uFPQ7Bwu9U" role="3clF47">
+          <node concept="3clFbF" id="7ISVfSIioV" role="3cqZAp">
+            <node concept="37vLTI" id="7ISVfSIioX" role="3clFbG">
+              <node concept="2OqwBi" id="7ISVfSIip1" role="37vLTJ">
+                <node concept="Xjq3P" id="7ISVfSIip4" role="2Oq$k0" />
+                <node concept="2OwXpG" id="7ISVfSIip0" role="2OqNvi">
+                  <ref role="2Oxat5" node="7ISVfSIioQ" resolve="predicateSymbols" />
+                </node>
+              </node>
+              <node concept="37vLTw" id="7ISVfSIip5" role="37vLTx">
+                <ref role="3cqZAo" node="5uFPQ7BwufO" resolve="predicateSymbols" />
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             </node>
           </node>
-          <node concept="3clFbF" id="5mr7UHchhEK" role="3cqZAp">
-            <node concept="37vLTw" id="5mr7UHchhEM" role="3clFbG">
-              <ref role="3cqZAo" to="rchb:7ISVfSIioQ" resolve="predicateSymbols" />
-            </node>
+          <node concept="3clFbF" id="7ISVfSIiJ6" role="3cqZAp">
+            <node concept="Xjq3P" id="7ISVfSIiJ4" role="3clFbG" />
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-      <node concept="3clFb_" id="5mr7UHcbx7o" role="jymVt">
-        <property role="TrG5h" value="getComputingTracer" />
-        <node concept="3uibUv" id="5mr7UHcbx7p" role="3clF45">
-          <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
+        <node concept="2AHcQZ" id="5jPBdK_lg1" role="2AJF6D">
+          <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
         </node>
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-        <node concept="3clFbS" id="5mr7UHcbx7r" role="3clF47">
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-            <node concept="37vLTw" id="5mr7UHcbx7n" role="3clFbG">
-              <ref role="3cqZAo" to="rchb:5mr7UHcbs2A" resolve="computingTracer" />
-            </node>
+      </node>
+      <node concept="2tJIrI" id="5uFPQ7Bwvfj" role="jymVt" />
+      <node concept="3clFb_" id="5uFPQ7Bwvg_" role="jymVt">
+        <property role="TrG5h" value="withTrace" />
+        <node concept="37vLTG" id="5mr7UHcbrGT" role="3clF46">
+          <property role="TrG5h" value="computingTracer" />
+          <node concept="3uibUv" id="5mr7UHcbrPY" role="1tU5fm">
+            <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
           </node>
         </node>
+        <node concept="3uibUv" id="5uFPQ7Bwvia" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5uFPQ7BwvgC" role="1B3o_S" />
+        <node concept="3clFbS" id="5uFPQ7BwvgD" role="3clF47">
+          <node concept="3clFbF" id="5mr7UHcbs2E" role="3cqZAp">
+            <node concept="37vLTI" id="5mr7UHcbs2G" role="3clFbG">
+              <node concept="2OqwBi" id="5mr7UHcbs2K" role="37vLTJ">
+                <node concept="Xjq3P" id="5mr7UHcbs2N" role="2Oq$k0" />
+                <node concept="2OwXpG" id="5mr7UHcbs2J" role="2OqNvi">
+                  <ref role="2Oxat5" node="5mr7UHcbs2A" resolve="computingTracer" />
+                </node>
+              </node>
+              <node concept="37vLTw" id="5mr7UHcbs2O" role="37vLTx">
+                <ref role="3cqZAo" node="5mr7UHcbrGT" resolve="computingTracer" />
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbF" id="5uFPQ7BwvnB" role="3cqZAp">
+            <node concept="Xjq3P" id="5uFPQ7BwvnA" role="3clFbG" />
+          </node>
+        </node>
+        <node concept="2AHcQZ" id="5jPBdK_lwj" role="2AJF6D">
+          <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+        </node>
       </node>
-      <node concept="2tJIrI" id="5mr7UHcbybF" role="jymVt" />
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-          <node concept="3uibUv" id="5mr7UHcbx7j" role="11_B2D">
+      <node concept="2tJIrI" id="5mr7UHcbcbV" role="jymVt" />
+      <node concept="3clFb_" id="5mr7UHcbbR2" role="jymVt">
+        <property role="TrG5h" value="withParam" />
+        <node concept="37vLTG" id="5mr7UHcbcpj" role="3clF46">
+          <property role="TrG5h" value="key" />
+          <node concept="17QB3L" id="5mr7UHcbcs$" role="1tU5fm" />
+        </node>
+        <node concept="37vLTG" id="5mr7UHcbctA" role="3clF46">
+          <property role="TrG5h" value="param" />
+          <node concept="3uibUv" id="5mr7UHcbcxl" role="1tU5fm">
             <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
           </node>
         </node>
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-              <ref role="3cqZAo" to="rchb:5mr7UHcbcAv" resolve="parameters" />
+        <node concept="3uibUv" id="5mr7UHcbjuP" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5mr7UHcbbR5" role="1B3o_S" />
+        <node concept="3clFbS" id="5mr7UHcbbR6" role="3clF47">
+          <node concept="3clFbF" id="5mr7UHcbdeU" role="3cqZAp">
+            <node concept="2OqwBi" id="5mr7UHcbdgN" role="3clFbG">
+              <node concept="37vLTw" id="5mr7UHcbdeT" role="2Oq$k0">
+                <ref role="3cqZAo" node="5mr7UHcbcAv" resolve="parameters" />
+              </node>
+              <node concept="liA8E" id="5mr7UHcbdni" role="2OqNvi">
+                <ref role="37wK5l" to="33ny:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
+                <node concept="37vLTw" id="5mr7UHcbdq7" role="37wK5m">
+                  <ref role="3cqZAo" node="5mr7UHcbcpj" resolve="key" />
+                </node>
+                <node concept="37vLTw" id="5mr7UHcbdvq" role="37wK5m">
+                  <ref role="3cqZAo" node="5mr7UHcbctA" resolve="param" />
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+              </node>
             </node>
           </node>
+          <node concept="3clFbF" id="5mr7UHcbjFr" role="3cqZAp">
+            <node concept="Xjq3P" id="5mr7UHcbjFp" role="3clFbG" />
+          </node>
+        </node>
+        <node concept="2AHcQZ" id="5jPBdK_lKH" role="2AJF6D">
+          <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
+        </node>
+      </node>
+      <node concept="2tJIrI" id="5mr7UHcbwTX" role="jymVt" />
+      <node concept="312cEg" id="7ISVfSIioQ" role="jymVt">
+        <property role="TrG5h" value="predicateSymbols" />
+        <node concept="3Tmbuc" id="5mr7UHcbtUi" role="1B3o_S" />
+        <node concept="10Q1$e" id="7ISVfSIix5" role="1tU5fm">
+          <node concept="3uibUv" id="7ISVfSIix7" role="10Q1$1">
+            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+          </node>
+        </node>
+      </node>
+      <node concept="312cEg" id="5mr7UHcbcAv" role="jymVt">
+        <property role="TrG5h" value="parameters" />
+        <node concept="3Tmbuc" id="5mr7UHcbtVS" role="1B3o_S" />
+        <node concept="3uibUv" id="5mr7UHcbcEh" role="1tU5fm">
+          <ref role="3uigEE" to="33ny:~Map" resolve="Map" />
+          <node concept="17QB3L" id="5mr7UHcbcEz" role="11_B2D" />
+          <node concept="3uibUv" id="5mr7UHcbcF8" role="11_B2D">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+        <node concept="2ShNRf" id="5mr7UHcbcTG" role="33vP2m">
+          <node concept="1pGfFk" id="5mr7UHcbd42" role="2ShVmc">
+            <ref role="37wK5l" to="33ny:~HashMap.&lt;init&gt;()" resolve="HashMap" />
+            <node concept="17QB3L" id="5mr7UHcbd7P" role="1pMfVU" />
+            <node concept="3uibUv" id="5mr7UHcbdce" role="1pMfVU">
+              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="312cEg" id="5mr7UHcbs2A" role="jymVt">
+        <property role="TrG5h" value="computingTracer" />
+        <node concept="3Tmbuc" id="5mr7UHcbtYG" role="1B3o_S" />
+        <node concept="3uibUv" id="5mr7UHcbs2D" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
         </node>
       </node>
       <node concept="2tJIrI" id="5mr7UHcbDBk" role="jymVt" />
@@ -974,8 +948,8 @@
                 <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
               </node>
               <node concept="2OqwBi" id="5mr7UHcbEN9" role="33vP2m">
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-                  <ref role="3cqZAo" to="rchb:5mr7UHcbcAv" resolve="parameters" />
+                <node concept="37vLTw" id="5jPBdK_mjF" role="2Oq$k0">
+                  <ref role="3cqZAo" node="5mr7UHcbcAv" resolve="parameters" />
                 </node>
                 <node concept="liA8E" id="5mr7UHcbENb" role="2OqNvi">
                   <ref role="37wK5l" to="33ny:~Map.get(java.lang.Object):java.lang.Object" resolve="get" />
@@ -1106,405 +1080,6 @@
       <node concept="2tJIrI" id="7ISVfSIezb" role="jymVt" />
     </node>
     <node concept="2tJIrI" id="7ISVfSIeeE" role="jymVt" />
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-                <node concept="10M0yZ" id="7ISVfSIJrd" role="2Oq$k0">
-                  <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
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-                </node>
-                <node concept="liA8E" id="7ISVfSIJAs" role="2OqNvi">
-                  <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
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-                          <node concept="37vLTw" id="7ISVfSIYOD" role="37wK5m">
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-                <node concept="liA8E" id="7ISVfSIJIa" role="2OqNvi">
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-                        <node concept="3uibUv" id="7ISVfSIZhr" role="10QFUM">
-                          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-                        </node>
-                        <node concept="37vLTw" id="7ISVfSIZhs" role="10QFUP">
-                          <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                        </node>
-                      </node>
-                      <node concept="2ShNRf" id="7ISVfSIZht" role="37wK5m">
-                        <node concept="1pGfFk" id="7ISVfSIZhu" role="2ShVmc">
-                          <ref role="37wK5l" to="95zw:6infEALANZc" resolve="AssertSolverImpl" />
-                        </node>
-                      </node>
-                    </node>
-                  </node>
-                </node>
-                <node concept="3clFbH" id="7ISVfSIZlS" role="3cqZAp" />
-              </node>
-            </node>
-            <node concept="3eNFk2" id="7ISVfSIJJE" role="3eNLev">
-              <node concept="2OqwBi" id="7ISVfSIJJF" role="3eO9$A">
-                <node concept="10M0yZ" id="7ISVfSIK8M" role="2Oq$k0">
-                  <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
-                  <ref role="3cqZAo" to="xq5w:5uFPQ7C26$b" resolve="BOUND_SYM" />
-                </node>
-                <node concept="liA8E" id="7ISVfSIJJH" role="2OqNvi">
-                  <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
-                  <node concept="37vLTw" id="7ISVfSIJJI" role="37wK5m">
-                    <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                  </node>
-                </node>
-              </node>
-              <node concept="3clFbS" id="7ISVfSIJJJ" role="3eOfB_">
-                <node concept="3clFbF" id="7ISVfSJ2P6" role="3cqZAp">
-                  <node concept="2OqwBi" id="7ISVfSJ2P7" role="3clFbG">
-                    <node concept="37vLTw" id="7ISVfSJ2P8" role="2Oq$k0">
-                      <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
-                    </node>
-                    <node concept="liA8E" id="7ISVfSJ2P9" role="2OqNvi">
-                      <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
-                      <node concept="10QFUN" id="7ISVfSJ2Pa" role="37wK5m">
-                        <node concept="3uibUv" id="7ISVfSJ2Pb" role="10QFUM">
-                          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-                        </node>
-                        <node concept="37vLTw" id="7ISVfSJ2Pc" role="10QFUP">
-                          <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                        </node>
-                      </node>
-                      <node concept="2ShNRf" id="7ISVfSJ2Pd" role="37wK5m">
-                        <node concept="HV5vD" id="7ISVfSJ2Zy" role="2ShVmc">
-                          <ref role="HV5vE" to="95zw:7ISVfSJ0DF" resolve="LogicalSolverImpl.Bound" />
-                        </node>
-                      </node>
-                    </node>
-                  </node>
-                </node>
-                <node concept="3clFbH" id="7ISVfSJ2Np" role="3cqZAp" />
-              </node>
-            </node>
-            <node concept="3eNFk2" id="7ISVfSJ2Gd" role="3eNLev">
-              <node concept="2OqwBi" id="7ISVfSJ2Ge" role="3eO9$A">
-                <node concept="10M0yZ" id="7ISVfSJ2Gf" role="2Oq$k0">
-                  <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
-                  <ref role="3cqZAo" to="xq5w:5uFPQ7C279$" resolve="FREE_SYM" />
-                </node>
-                <node concept="liA8E" id="7ISVfSJ2Gg" role="2OqNvi">
-                  <ref role="37wK5l" to="qrld:54i3Fxd17bK" resolve="equals" />
-                  <node concept="37vLTw" id="7ISVfSJ2Gh" role="37wK5m">
-                    <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                  </node>
-                </node>
-              </node>
-              <node concept="3clFbS" id="7ISVfSJ2Gi" role="3eOfB_">
-                <node concept="3clFbF" id="7ISVfSJ30n" role="3cqZAp">
-                  <node concept="2OqwBi" id="7ISVfSJ30o" role="3clFbG">
-                    <node concept="37vLTw" id="7ISVfSJ30p" role="2Oq$k0">
-                      <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
-                    </node>
-                    <node concept="liA8E" id="7ISVfSJ30q" role="2OqNvi">
-                      <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
-                      <node concept="10QFUN" id="7ISVfSJ30r" role="37wK5m">
-                        <node concept="3uibUv" id="7ISVfSJ30s" role="10QFUM">
-                          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-                        </node>
-                        <node concept="37vLTw" id="7ISVfSJ30t" role="10QFUP">
-                          <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                        </node>
-                      </node>
-                      <node concept="2ShNRf" id="7ISVfSJ30u" role="37wK5m">
-                        <node concept="HV5vD" id="7ISVfSJ3cx" role="2ShVmc">
-                          <ref role="HV5vE" to="95zw:7ISVfSJ1oi" resolve="LogicalSolverImpl.Free" />
-                        </node>
-                      </node>
-                    </node>
-                  </node>
-                </node>
-                <node concept="3clFbH" id="7ISVfSJ2Nu" role="3cqZAp" />
-              </node>
-            </node>
-            <node concept="9aQIb" id="5mr7UHchgcy" role="9aQIa">
-              <node concept="3clFbS" id="5mr7UHchgcz" role="9aQI4">
-                <node concept="YS8fn" id="5mr7UHchgjZ" role="3cqZAp">
-                  <node concept="2ShNRf" id="5mr7UHchgme" role="YScLw">
-                    <node concept="1pGfFk" id="5mr7UHchgDA" role="2ShVmc">
-                      <ref role="37wK5l" to="wyt6:~IllegalArgumentException.&lt;init&gt;(java.lang.String)" resolve="IllegalArgumentException" />
-                      <node concept="3cpWs3" id="5mr7UHchgIt" role="37wK5m">
-                        <node concept="37vLTw" id="5mr7UHchgKN" role="3uHU7w">
-                          <ref role="3cqZAo" node="7ISVfSIJee" resolve="symbol" />
-                        </node>
-                        <node concept="Xl_RD" id="5mr7UHchgEB" role="3uHU7B">
-                          <property role="Xl_RC" value="unknown symbol: " />
-                        </node>
-                      </node>
-                    </node>
-                  </node>
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3clFbH" id="5mr7UHcbFmH" role="3cqZAp" />
-        </node>
-      </node>
-      <node concept="2tJIrI" id="5mr7UHch7aO" role="jymVt" />
-      <node concept="3clFb_" id="6Kcfpq7Bs88" role="jymVt">
-        <property role="TrG5h" value="registerHandler" />
-        <node concept="37vLTG" id="7ISVfSIOyP" role="3clF46">
-          <property role="TrG5h" value="symbol" />
-          <node concept="3uibUv" id="7ISVfSIOGX" role="1tU5fm">
-            <ref role="3uigEE" to="qrld:5uFPQ7B$mzX" resolve="Symbol" />
-          </node>
-        </node>
-        <node concept="37vLTG" id="6Kcfpq7BtOW" role="3clF46">
-          <property role="TrG5h" value="instructible" />
-          <node concept="3uibUv" id="6Kcfpq7BtZc" role="1tU5fm">
-            <ref role="3uigEE" to="qrld:6Kcfpq7AXVG" resolve="Instructible" />
-          </node>
-        </node>
-        <node concept="3cqZAl" id="6Kcfpq7Bs8a" role="3clF45" />
-        <node concept="3Tmbuc" id="6Kcfpq7BskN" role="1B3o_S" />
-        <node concept="3clFbS" id="6Kcfpq7Bs8c" role="3clF47">
-          <node concept="3clFbF" id="6Kcfpq7Bu1B" role="3cqZAp">
-            <node concept="2OqwBi" id="6Kcfpq7Bu22" role="3clFbG">
-              <node concept="37vLTw" id="7ISVfSIOWI" role="2Oq$k0">
-                <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
-              </node>
-              <node concept="liA8E" id="6Kcfpq7Bu2G" role="2OqNvi">
-                <ref role="37wK5l" to="qrld:6Kcfpq7B2yH" resolve="registerHandler" />
-                <node concept="37vLTw" id="7ISVfSIOLP" role="37wK5m">
-                  <ref role="3cqZAo" node="7ISVfSIOyP" resolve="symbol" />
-                </node>
-                <node concept="37vLTw" id="6Kcfpq7Bu3W" role="37wK5m">
-                  <ref role="3cqZAo" node="6Kcfpq7BtOW" resolve="instructible" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2tJIrI" id="6Kcfpq7BuLv" role="jymVt" />
-      <node concept="3clFb_" id="6Kcfpq7Buzk" role="jymVt">
-        <property role="TrG5h" value="registerSolver" />
-        <node concept="37vLTG" id="7ISVfSIOZm" role="3clF46">
-          <property role="TrG5h" value="predicateSymbol" />
-          <node concept="3uibUv" id="7ISVfSIPw0" role="1tU5fm">
-            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-          </node>
-        </node>
-        <node concept="37vLTG" id="6Kcfpq7Buzn" role="3clF46">
-          <property role="TrG5h" value="queryable" />
-          <node concept="3uibUv" id="6Kcfpq7Bw2C" role="1tU5fm">
-            <ref role="3uigEE" to="qrld:6Kcfpq7AYBh" resolve="Queryable" />
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-        </node>
-        <node concept="3cqZAl" id="6Kcfpq7Buzp" role="3clF45" />
-        <node concept="3Tmbuc" id="6Kcfpq7Buzq" role="1B3o_S" />
-        <node concept="3clFbS" id="6Kcfpq7Buzr" role="3clF47">
-          <node concept="3clFbF" id="6Kcfpq7Buzs" role="3cqZAp">
-            <node concept="2OqwBi" id="6Kcfpq7Buzt" role="3clFbG">
-              <node concept="37vLTw" id="7ISVfSIPqq" role="2Oq$k0">
-                <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
-              </node>
-              <node concept="liA8E" id="6Kcfpq7Buzv" role="2OqNvi">
-                <ref role="37wK5l" to="qrld:6Kcfpq7B2LV" resolve="registerSolver" />
-                <node concept="37vLTw" id="7ISVfSIPef" role="37wK5m">
-                  <ref role="3cqZAo" node="7ISVfSIOZm" resolve="predicateSymbol" />
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-                <node concept="37vLTw" id="6Kcfpq7Buzx" role="37wK5m">
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-                <ref role="3cqZAo" node="5mr7UHch7DV" resolve="computingSession" />
-              </node>
-              <node concept="liA8E" id="4xBopTzylBk" role="2OqNvi">
-                <ref role="37wK5l" to="qrld:6Kcfpq7B2yH" resolve="registerHandler" />
-                <node concept="37vLTw" id="7ISVfSIPfC" role="37wK5m">
-                  <ref role="3cqZAo" node="7ISVfSIOZm" resolve="predicateSymbol" />
-                </node>
-                <node concept="37vLTw" id="4xBopTzylH0" role="37wK5m">
-                  <ref role="3cqZAo" node="6Kcfpq7Buzn" resolve="queryable" />
-                </node>
-              </node>
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="2tJIrI" id="5uFPQ7BZbUe" role="jymVt" />
-      <node concept="2tJIrI" id="7ISVfSIy3Y" role="jymVt" />
-      <node concept="3Tm6S6" id="5mr7UHchbHJ" role="1B3o_S" />
-      <node concept="312cEg" id="5mr7UHch7DV" role="jymVt">
-        <property role="TrG5h" value="computingSession" />
-        <node concept="3Tm6S6" id="5mr7UHch7DW" role="1B3o_S" />
-        <node concept="3uibUv" id="5mr7UHch7DY" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
-        </node>
-      </node>
-      <node concept="2tJIrI" id="5mr7UHchpFD" role="jymVt" />
-      <node concept="312cEg" id="5mr7UHchbU9" role="jymVt">
-        <property role="TrG5h" value="computingTracer" />
-        <node concept="3Tm6S6" id="5mr7UHchbUa" role="1B3o_S" />
-        <node concept="3uibUv" id="5mr7UHchbUc" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
-        </node>
-      </node>
-    </node>
     <node concept="2tJIrI" id="7ISVfSIszY" role="jymVt" />
     <node concept="3Tm1VV" id="7ISVfSIedR" role="1B3o_S" />
     <node concept="3uibUv" id="7ISVfSIefW" role="1zkMxy">
diff --git a/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/constraint.mps b/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/constraint.mps
index 842a5fea..14620297 100644
--- a/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/constraint.mps
+++ b/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/constraint.mps
@@ -874,6 +874,27 @@
             </node>
           </node>
         </node>
+        <node concept="3SKdUt" id="5jPBdK_GNG" role="3cqZAp">
+          <node concept="3SKdUq" id="5jPBdK_GNI" role="3SKWNk">
+            <property role="3SKdUp" value="TODO: must we keep them twice?" />
+          </node>
+        </node>
+        <node concept="3clFbF" id="5jPBdK_Gux" role="3cqZAp">
+          <node concept="2OqwBi" id="5jPBdK_Guy" role="3clFbG">
+            <node concept="37vLTw" id="5jPBdK_Guz" role="2Oq$k0">
+              <ref role="3cqZAo" node="2GO7tyJTzV1" resolve="handlers" />
+            </node>
+            <node concept="liA8E" id="5jPBdK_Gu$" role="2OqNvi">
+              <ref role="37wK5l" to="33ny:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
+              <node concept="37vLTw" id="5jPBdK_GCX" role="37wK5m">
+                <ref role="3cqZAo" node="6Kcfpq7B2LZ" resolve="constraint" />
+              </node>
+              <node concept="37vLTw" id="5jPBdK_GFX" role="37wK5m">
+                <ref role="3cqZAo" node="6Kcfpq7B2M1" resolve="queryable" />
+              </node>
+            </node>
+          </node>
+        </node>
       </node>
       <node concept="37vLTG" id="6Kcfpq7B2LZ" role="3clF46">
         <property role="TrG5h" value="constraint" />
diff --git a/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/program.mps b/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/program.mps
index 91bf40dc..7e098f22 100644
--- a/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/program.mps
+++ b/languages/jetbrains.mps.logic/reactor/models/jetbrains/mps/logic/reactor/program.mps
@@ -28,14 +28,10 @@
         <child id="1197027771414" name="operand" index="2Oq$k0" />
         <child id="1197027833540" name="operation" index="2OqNvi" />
       </concept>
-      <concept id="1197029447546" name="jetbrains.mps.baseLanguage.structure.FieldReferenceOperation" flags="nn" index="2OwXpG">
-        <reference id="1197029500499" name="fieldDeclaration" index="2Oxat5" />
-      </concept>
       <concept id="1145552977093" name="jetbrains.mps.baseLanguage.structure.GenericNewExpression" flags="nn" index="2ShNRf">
         <child id="1145553007750" name="creator" index="2ShVmc" />
       </concept>
       <concept id="1070462154015" name="jetbrains.mps.baseLanguage.structure.StaticFieldDeclaration" flags="ig" index="Wx3nA" />
-      <concept id="1070475354124" name="jetbrains.mps.baseLanguage.structure.ThisExpression" flags="nn" index="Xjq3P" />
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
@@ -44,16 +40,9 @@
         <child id="1164991057263" name="throwable" index="YScLw" />
       </concept>
       <concept id="1070534058343" name="jetbrains.mps.baseLanguage.structure.NullLiteral" flags="nn" index="10Nm6u" />
-      <concept id="1070534760951" name="jetbrains.mps.baseLanguage.structure.ArrayType" flags="in" index="10Q1$e">
-        <child id="1070534760952" name="componentType" index="10Q1$1" />
-      </concept>
-      <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" />
       </concept>
-      <concept id="1068431474542" name="jetbrains.mps.baseLanguage.structure.VariableDeclaration" flags="ng" index="33uBYm">
-        <child id="1068431790190" name="initializer" index="33vP2m" />
-      </concept>
       <concept id="1068498886296" name="jetbrains.mps.baseLanguage.structure.VariableReference" flags="nn" index="37vLTw">
         <reference id="1068581517664" name="variableDeclaration" index="3cqZAo" />
       </concept>
@@ -64,6 +53,8 @@
         <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" />
@@ -82,15 +73,12 @@
       <concept id="1068580123136" name="jetbrains.mps.baseLanguage.structure.StatementList" flags="sn" stub="5293379017992965193" index="3clFbS">
         <child id="1068581517665" name="statement" index="3cqZAp" />
       </concept>
-      <concept id="1068580123140" name="jetbrains.mps.baseLanguage.structure.ConstructorDeclaration" flags="ig" index="3clFbW" />
       <concept id="1068581517677" name="jetbrains.mps.baseLanguage.structure.VoidType" flags="in" index="3cqZAl" />
       <concept id="1204053956946" name="jetbrains.mps.baseLanguage.structure.IMethodCall" flags="ng" index="1ndlxa">
         <reference id="1068499141037" name="baseMethodDeclaration" index="37wK5l" />
         <child id="1068499141038" name="actualArgument" index="37wK5m" />
       </concept>
-      <concept id="1212685548494" name="jetbrains.mps.baseLanguage.structure.ClassCreator" flags="nn" index="1pGfFk">
-        <child id="1212687122400" name="typeParameter" index="1pMfVU" />
-      </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" />
@@ -269,14 +257,9 @@
       <property role="TrG5h" value="Config" />
       <property role="1sVAO0" value="true" />
       <node concept="2tJIrI" id="5uFPQ7BwtaY" role="jymVt" />
-      <node concept="3clFbW" id="7ISVfSIxgm" role="jymVt">
-        <node concept="3cqZAl" id="7ISVfSIxgp" role="3clF45" />
-        <node concept="3Tmbuc" id="5mr7UHcbwBO" role="1B3o_S" />
-        <node concept="3clFbS" id="7ISVfSIxgr" role="3clF47" />
-      </node>
-      <node concept="2tJIrI" id="7ISVfSIwT4" role="jymVt" />
       <node concept="3clFb_" id="5uFPQ7Bwu9Q" role="jymVt">
         <property role="TrG5h" value="withPredicates" />
+        <property role="1EzhhJ" value="true" />
         <node concept="37vLTG" id="5uFPQ7BwufO" role="3clF46">
           <property role="TrG5h" value="predicateSymbols" />
           <node concept="8X2XB" id="5uFPQ7BwuhP" role="1tU5fm">
@@ -289,28 +272,12 @@
           <ref role="3uigEE" node="5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
         </node>
         <node concept="3Tm1VV" id="5uFPQ7Bwu9T" role="1B3o_S" />
-        <node concept="3clFbS" id="5uFPQ7Bwu9U" role="3clF47">
-          <node concept="3clFbF" id="7ISVfSIioV" role="3cqZAp">
-            <node concept="37vLTI" id="7ISVfSIioX" role="3clFbG">
-              <node concept="2OqwBi" id="7ISVfSIip1" role="37vLTJ">
-                <node concept="Xjq3P" id="7ISVfSIip4" role="2Oq$k0" />
-                <node concept="2OwXpG" id="7ISVfSIip0" role="2OqNvi">
-                  <ref role="2Oxat5" node="7ISVfSIioQ" resolve="predicateSymbols" />
-                </node>
-              </node>
-              <node concept="37vLTw" id="7ISVfSIip5" role="37vLTx">
-                <ref role="3cqZAo" node="5uFPQ7BwufO" resolve="predicateSymbols" />
-              </node>
-            </node>
-          </node>
-          <node concept="3clFbF" id="7ISVfSIiJ6" role="3cqZAp">
-            <node concept="Xjq3P" id="7ISVfSIiJ4" role="3clFbG" />
-          </node>
-        </node>
+        <node concept="3clFbS" id="5uFPQ7Bwu9U" role="3clF47" />
       </node>
       <node concept="2tJIrI" id="5uFPQ7Bwvfj" role="jymVt" />
       <node concept="3clFb_" id="5uFPQ7Bwvg_" role="jymVt">
         <property role="TrG5h" value="withTrace" />
+        <property role="1EzhhJ" value="true" />
         <node concept="37vLTG" id="5mr7UHcbrGT" role="3clF46">
           <property role="TrG5h" value="computingTracer" />
           <node concept="3uibUv" id="5mr7UHcbrPY" role="1tU5fm">
@@ -321,28 +288,12 @@
           <ref role="3uigEE" node="5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
         </node>
         <node concept="3Tm1VV" id="5uFPQ7BwvgC" role="1B3o_S" />
-        <node concept="3clFbS" id="5uFPQ7BwvgD" role="3clF47">
-          <node concept="3clFbF" id="5mr7UHcbs2E" role="3cqZAp">
-            <node concept="37vLTI" id="5mr7UHcbs2G" role="3clFbG">
-              <node concept="2OqwBi" id="5mr7UHcbs2K" role="37vLTJ">
-                <node concept="Xjq3P" id="5mr7UHcbs2N" role="2Oq$k0" />
-                <node concept="2OwXpG" id="5mr7UHcbs2J" role="2OqNvi">
-                  <ref role="2Oxat5" node="5mr7UHcbs2A" resolve="computingTracer" />
-                </node>
-              </node>
-              <node concept="37vLTw" id="5mr7UHcbs2O" role="37vLTx">
-                <ref role="3cqZAo" node="5mr7UHcbrGT" resolve="computingTracer" />
-              </node>
-            </node>
-          </node>
-          <node concept="3clFbF" id="5uFPQ7BwvnB" role="3cqZAp">
-            <node concept="Xjq3P" id="5uFPQ7BwvnA" role="3clFbG" />
-          </node>
-        </node>
+        <node concept="3clFbS" id="5uFPQ7BwvgD" role="3clF47" />
       </node>
       <node concept="2tJIrI" id="5mr7UHcbcbV" role="jymVt" />
       <node concept="3clFb_" id="5mr7UHcbbR2" role="jymVt">
         <property role="TrG5h" value="withParam" />
+        <property role="1EzhhJ" value="true" />
         <node concept="37vLTG" id="5mr7UHcbcpj" role="3clF46">
           <property role="TrG5h" value="key" />
           <node concept="17QB3L" id="5mr7UHcbcs$" role="1tU5fm" />
@@ -357,27 +308,7 @@
           <ref role="3uigEE" node="5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
         </node>
         <node concept="3Tm1VV" id="5mr7UHcbbR5" role="1B3o_S" />
-        <node concept="3clFbS" id="5mr7UHcbbR6" role="3clF47">
-          <node concept="3clFbF" id="5mr7UHcbdeU" role="3cqZAp">
-            <node concept="2OqwBi" id="5mr7UHcbdgN" role="3clFbG">
-              <node concept="37vLTw" id="5mr7UHcbdeT" role="2Oq$k0">
-                <ref role="3cqZAo" node="5mr7UHcbcAv" resolve="parameters" />
-              </node>
-              <node concept="liA8E" id="5mr7UHcbdni" role="2OqNvi">
-                <ref role="37wK5l" to="33ny:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
-                <node concept="37vLTw" id="5mr7UHcbdq7" role="37wK5m">
-                  <ref role="3cqZAo" node="5mr7UHcbcpj" resolve="key" />
-                </node>
-                <node concept="37vLTw" id="5mr7UHcbdvq" role="37wK5m">
-                  <ref role="3cqZAo" node="5mr7UHcbctA" resolve="param" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3clFbF" id="5mr7UHcbjFr" role="3cqZAp">
-            <node concept="Xjq3P" id="5mr7UHcbjFp" role="3clFbG" />
-          </node>
-        </node>
+        <node concept="3clFbS" id="5mr7UHcbbR6" role="3clF47" />
       </node>
       <node concept="2tJIrI" id="5mr7UHcb$Ol" role="jymVt" />
       <node concept="3clFb_" id="7ISVfSIuSh" role="jymVt">
@@ -389,44 +320,7 @@
         <node concept="3Tm1VV" id="7ISVfSIuSk" role="1B3o_S" />
         <node concept="3clFbS" id="7ISVfSIuSl" role="3clF47" />
       </node>
-      <node concept="2tJIrI" id="5mr7UHcbwTX" role="jymVt" />
       <node concept="3Tm1VV" id="5uFPQ7Bwt90" role="1B3o_S" />
-      <node concept="312cEg" id="7ISVfSIioQ" role="jymVt">
-        <property role="TrG5h" value="predicateSymbols" />
-        <node concept="3Tmbuc" id="5mr7UHcbtUi" role="1B3o_S" />
-        <node concept="10Q1$e" id="7ISVfSIix5" role="1tU5fm">
-          <node concept="3uibUv" id="7ISVfSIix7" role="10Q1$1">
-            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-          </node>
-        </node>
-      </node>
-      <node concept="312cEg" id="5mr7UHcbcAv" role="jymVt">
-        <property role="TrG5h" value="parameters" />
-        <node concept="3Tmbuc" id="5mr7UHcbtVS" role="1B3o_S" />
-        <node concept="3uibUv" id="5mr7UHcbcEh" role="1tU5fm">
-          <ref role="3uigEE" to="33ny:~Map" resolve="Map" />
-          <node concept="17QB3L" id="5mr7UHcbcEz" role="11_B2D" />
-          <node concept="3uibUv" id="5mr7UHcbcF8" role="11_B2D">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-        <node concept="2ShNRf" id="5mr7UHcbcTG" role="33vP2m">
-          <node concept="1pGfFk" id="5mr7UHcbd42" role="2ShVmc">
-            <ref role="37wK5l" to="33ny:~HashMap.&lt;init&gt;()" resolve="HashMap" />
-            <node concept="17QB3L" id="5mr7UHcbd7P" role="1pMfVU" />
-            <node concept="3uibUv" id="5mr7UHcbdce" role="1pMfVU">
-              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-            </node>
-          </node>
-        </node>
-      </node>
-      <node concept="312cEg" id="5mr7UHcbs2A" role="jymVt">
-        <property role="TrG5h" value="computingTracer" />
-        <node concept="3Tmbuc" id="5mr7UHcbtYG" role="1B3o_S" />
-        <node concept="3uibUv" id="5mr7UHcbs2D" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
-        </node>
-      </node>
     </node>
     <node concept="2tJIrI" id="5uFPQ7Bwwl1" role="jymVt" />
     <node concept="3clFb_" id="7ISVfSIWX_" role="jymVt">
@@ -449,50 +343,6 @@
       <node concept="3clFbS" id="5uFPQ7ClOzE" role="3clF47" />
     </node>
     <node concept="2tJIrI" id="5uFPQ7ClOwd" role="jymVt" />
-    <node concept="3clFb_" id="5uFPQ7BvQw$" role="jymVt">
-      <property role="TrG5h" value="tell" />
-      <property role="1EzhhJ" value="true" />
-      <node concept="3cqZAl" id="5uFPQ7BvQwA" role="3clF45" />
-      <node concept="3Tm1VV" id="5uFPQ7BvQwB" role="1B3o_S" />
-      <node concept="3clFbS" id="5uFPQ7BvQwC" role="3clF47" />
-      <node concept="37vLTG" id="5uFPQ7Bwx2C" role="3clF46">
-        <property role="TrG5h" value="symbol" />
-        <node concept="3uibUv" id="7ISVfSIoMW" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:5uFPQ7B$mzX" resolve="Symbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="5uFPQ7BZbqc" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="5uFPQ7BZbuR" role="1tU5fm">
-          <node concept="3uibUv" id="5uFPQ7BZbuk" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-    </node>
-    <node concept="2tJIrI" id="5uFPQ7BZb$P" role="jymVt" />
-    <node concept="3clFb_" id="5uFPQ7Bwy32" role="jymVt">
-      <property role="TrG5h" value="ask" />
-      <property role="1EzhhJ" value="true" />
-      <node concept="3cqZAl" id="5uFPQ7Bwy33" role="3clF45" />
-      <node concept="3Tm1VV" id="5uFPQ7Bwy34" role="1B3o_S" />
-      <node concept="3clFbS" id="5uFPQ7Bwy35" role="3clF47" />
-      <node concept="37vLTG" id="5uFPQ7Bwy36" role="3clF46">
-        <property role="TrG5h" value="predicateSymbol" />
-        <node concept="3uibUv" id="5uFPQ7BZbC_" role="1tU5fm">
-          <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
-        </node>
-      </node>
-      <node concept="37vLTG" id="7ISVfSIrPy" role="3clF46">
-        <property role="TrG5h" value="args" />
-        <node concept="8X2XB" id="7ISVfSIs2D" role="1tU5fm">
-          <node concept="3uibUv" id="7ISVfSIrW_" role="8Xvag">
-            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
-          </node>
-        </node>
-      </node>
-    </node>
-    <node concept="2tJIrI" id="5uFPQ7BvQx4" role="jymVt" />
     <node concept="3clFb_" id="5uFPQ7BvQyO" role="jymVt">
       <property role="TrG5h" value="constraintSymbols" />
       <property role="1EzhhJ" value="true" />
@@ -608,6 +458,52 @@
         </node>
       </node>
     </node>
+    <node concept="2tJIrI" id="5jPBdK_J2T" role="jymVt" />
+    <node concept="2YIFZL" id="5jPBdK_JeZ" role="jymVt">
+      <property role="DiZV1" value="false" />
+      <property role="od$2w" value="false" />
+      <property role="TrG5h" value="clearBackend" />
+      <node concept="37vLTG" id="5jPBdK_JrA" role="3clF46">
+        <property role="TrG5h" value="backend" />
+        <node concept="3uibUv" id="5jPBdK_JrB" role="1tU5fm">
+          <ref role="3uigEE" node="5uFPQ7BwtoR" resolve="EvaluationSession.Backend" />
+        </node>
+      </node>
+      <node concept="3clFbS" id="5jPBdK_J94" role="3clF47">
+        <node concept="3clFbJ" id="5jPBdK_JtX" role="3cqZAp">
+          <node concept="3clFbS" id="5jPBdK_JtY" role="3clFbx">
+            <node concept="YS8fn" id="5jPBdK_JtZ" role="3cqZAp">
+              <node concept="2ShNRf" id="5jPBdK_Ju0" role="YScLw">
+                <node concept="1pGfFk" id="5jPBdK_Ju1" role="2ShVmc">
+                  <ref role="37wK5l" to="wyt6:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
+                  <node concept="Xl_RD" id="5jPBdK_Ju2" role="37wK5m">
+                    <property role="Xl_RC" value="illegal access" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3y3z36" id="5jPBdK_Ju3" role="3clFbw">
+            <node concept="37vLTw" id="5jPBdK_Jws" role="3uHU7w">
+              <ref role="3cqZAo" node="5jPBdK_JrA" resolve="backend" />
+            </node>
+            <node concept="37vLTw" id="5jPBdK_Ju7" role="3uHU7B">
+              <ref role="3cqZAo" node="5uFPQ7BwtFE" resolve="ourBackend" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="5jPBdK_Ju9" role="3cqZAp">
+          <node concept="37vLTI" id="5jPBdK_Jua" role="3clFbG">
+            <node concept="10Nm6u" id="5jPBdK_JxG" role="37vLTx" />
+            <node concept="37vLTw" id="5jPBdK_Jue" role="37vLTJ">
+              <ref role="3cqZAo" node="5uFPQ7BwtFE" resolve="ourBackend" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="5jPBdK_J92" role="3clF45" />
+      <node concept="3Tmbuc" id="5jPBdK_Je4" role="1B3o_S" />
+    </node>
     <node concept="2tJIrI" id="5uFPQ7BwtL0" role="jymVt" />
     <node concept="Wx3nA" id="5uFPQ7BwtFE" role="jymVt">
       <property role="TrG5h" value="ourBackend" />
diff --git a/languages/jetbrains.mps.logic/test/jetbrains.mps.logic.test.msd b/languages/jetbrains.mps.logic/test/jetbrains.mps.logic.test.msd
index 3fc9425e..207e6cc8 100644
--- a/languages/jetbrains.mps.logic/test/jetbrains.mps.logic.test.msd
+++ b/languages/jetbrains.mps.logic/test/jetbrains.mps.logic.test.msd
@@ -20,6 +20,7 @@
     <dependency reexport="false">6354ebe7-c22a-4a0f-ac54-50b52ab9b065(JDK)</dependency>
     <dependency reexport="false">bbf5c548-7111-4a53-a117-cdefc664cf34(jetbrains.mps.logic.reactor)</dependency>
     <dependency reexport="false">760652ad-c01a-495e-9510-ed51532f617b(jetbrains.mps.logic.jchr)</dependency>
+    <dependency reexport="false">e4a4c488-aaf8-4c5b-bc98-e65c5dd9acb9(jetbrains.mps.lang.typesystem2.samplechecker.handler.test)</dependency>
   </dependencies>
   <usedDevKits>
     <usedDevKit>fbc25dd2-5da4-483a-8b19-70928e1b62d7(jetbrains.mps.devkit.general-purpose)</usedDevKit>
@@ -54,6 +55,7 @@
     <module reference="d7eb0a2a-bd50-4576-beae-e4a89db35f20(jetbrains.mps.lang.scopes.runtime)" version="0" />
     <module reference="c72da2b9-7cce-4447-8389-f407dc1158b7(jetbrains.mps.lang.structure)" version="0" />
     <module reference="9ded098b-ad6a-4657-bfd9-48636cfe8bc3(jetbrains.mps.lang.traceable)" version="0" />
+    <module reference="e4a4c488-aaf8-4c5b-bc98-e65c5dd9acb9(jetbrains.mps.lang.typesystem2.samplechecker.handler.test)" version="0" />
     <module reference="35320f26-77cb-4c55-be9f-a97a27770af1(jetbrains.mps.logic)" version="0" />
     <module reference="7526e0cf-1ce7-46f8-a555-9eca1e06c23b(jetbrains.mps.logic.atom)" version="0" />
     <module reference="760652ad-c01a-495e-9510-ed51532f617b(jetbrains.mps.logic.jchr)" version="0" />
diff --git a/languages/jetbrains.mps.logic/test/models/jetbrains/mps/logic/test/unification.mps b/languages/jetbrains.mps.logic/test/models/jetbrains/mps/logic/test/unification.mps
index 80aaf773..e6da417a 100644
--- a/languages/jetbrains.mps.logic/test/models/jetbrains/mps/logic/test/unification.mps
+++ b/languages/jetbrains.mps.logic/test/models/jetbrains/mps/logic/test/unification.mps
@@ -18,28 +18,43 @@
     <import index="45ys" ref="r:7365f7fe-12e6-4229-8901-f6dc6d5df03f(jetbrains.mps.logic.reactor.logical)" />
     <import index="qrld" ref="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)" />
     <import index="95zw" ref="r:f3ff7852-b9dd-4760-b213-a8a031c77d0e(jetbrains.mps.logic.jchr.predicate)" />
+    <import index="rchb" ref="r:f43ee4a0-488a-425a-87a0-594ab3b0d15f(jetbrains.mps.logic.reactor.program)" />
+    <import index="wyt6" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.lang(JDK/)" />
+    <import index="yhq8" ref="r:5a1f4b5d-8f7a-49a1-a68a-49cfbbceb473(jetbrains.mps.lang.typesystem2.samplechecker.handle.test.util)" />
   </imports>
   <registry>
     <language id="f3061a53-9226-4cc5-a443-f952ceaf5816" name="jetbrains.mps.baseLanguage">
+      <concept id="1219920932475" name="jetbrains.mps.baseLanguage.structure.VariableArityType" flags="in" index="8X2XB">
+        <child id="1219921048460" name="componentType" index="8Xvag" />
+      </concept>
       <concept id="1215693861676" name="jetbrains.mps.baseLanguage.structure.BaseAssignmentExpression" flags="nn" index="d038R">
         <child id="1068498886297" name="rValue" index="37vLTx" />
         <child id="1068498886295" name="lValue" index="37vLTJ" />
       </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="2820489544401957797" name="jetbrains.mps.baseLanguage.structure.DefaultClassCreator" flags="nn" index="HV5vD">
+        <reference id="2820489544401957798" name="classifier" index="HV5vE" />
+      </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" />
       </concept>
+      <concept id="1197029447546" name="jetbrains.mps.baseLanguage.structure.FieldReferenceOperation" flags="nn" index="2OwXpG">
+        <reference id="1197029500499" name="fieldDeclaration" index="2Oxat5" />
+      </concept>
       <concept id="1145552977093" name="jetbrains.mps.baseLanguage.structure.GenericNewExpression" flags="nn" index="2ShNRf">
         <child id="1145553007750" name="creator" index="2ShVmc" />
       </concept>
       <concept id="1137021947720" name="jetbrains.mps.baseLanguage.structure.ConceptFunction" flags="in" index="2VMwT0">
         <child id="1137022507850" name="body" index="2VODD2" />
       </concept>
+      <concept id="1070462154015" name="jetbrains.mps.baseLanguage.structure.StaticFieldDeclaration" flags="ig" index="Wx3nA" />
+      <concept id="1070475354124" name="jetbrains.mps.baseLanguage.structure.ThisExpression" flags="nn" index="Xjq3P" />
       <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="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>
@@ -47,12 +62,20 @@
         <reference id="1144433057691" name="classifier" index="1PxDUh" />
       </concept>
       <concept id="1070534058343" name="jetbrains.mps.baseLanguage.structure.NullLiteral" flags="nn" index="10Nm6u" />
+      <concept id="1070534760951" name="jetbrains.mps.baseLanguage.structure.ArrayType" flags="in" index="10Q1$e">
+        <child id="1070534760952" name="componentType" index="10Q1$1" />
+      </concept>
       <concept id="1070534934090" name="jetbrains.mps.baseLanguage.structure.CastExpression" flags="nn" index="10QFUN">
         <child id="1070534934091" name="type" index="10QFUM" />
         <child id="1070534934092" name="expression" index="10QFUP" />
       </concept>
       <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">
+        <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">
+        <property id="1176718929932" name="isFinal" index="3TUv4t" />
         <child id="1068431790190" name="initializer" index="33vP2m" />
       </concept>
       <concept id="1068498886296" name="jetbrains.mps.baseLanguage.structure.VariableReference" flags="nn" index="37vLTw">
@@ -69,7 +92,9 @@
         <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="1068580123155" name="jetbrains.mps.baseLanguage.structure.ExpressionStatement" flags="nn" index="3clFbF">
         <child id="1068580123156" name="expression" index="3clFbG" />
       </concept>
@@ -80,6 +105,7 @@
       <concept id="1068580123137" name="jetbrains.mps.baseLanguage.structure.BooleanConstant" flags="nn" index="3clFbT">
         <property id="1068580123138" name="value" index="3clFbU" />
       </concept>
+      <concept id="1068580123140" name="jetbrains.mps.baseLanguage.structure.ConstructorDeclaration" flags="ig" index="3clFbW" />
       <concept id="1068580320020" name="jetbrains.mps.baseLanguage.structure.IntegerConstant" flags="nn" index="3cmrfG">
         <property id="1068580320021" name="value" index="3cmrfH" />
       </concept>
@@ -97,6 +123,7 @@
       </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" />
@@ -1631,13 +1658,7 @@
         <ref role="3uigEE" to="eifs:~ConstraintSystem" resolve="ConstraintSystem" />
       </node>
     </node>
-    <node concept="312cEg" id="1OShD0Ift_R" role="jymVt">
-      <property role="TrG5h" value="unificationSolver" />
-      <node concept="3Tm6S6" id="1OShD0Ift_S" role="1B3o_S" />
-      <node concept="3uibUv" id="1OShD0Ift_T" role="1tU5fm">
-        <ref role="3uigEE" to="95zw:6njqcfQVO0n" resolve="UnificationSolver" />
-      </node>
-    </node>
+    <node concept="2tJIrI" id="5jPBdKMIHL" role="jymVt" />
     <node concept="2tJIrI" id="1OShD0Ifu78" role="jymVt" />
     <node concept="3clFb_" id="1OShD0Ifu8d" role="jymVt">
       <property role="TrG5h" value="var" />
@@ -1911,17 +1932,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0IfuGP" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0Ifv2C" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfuGR" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IfuGS" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdK_vh_" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_vpp" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_vmP" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdK_vlo" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdK_voQ" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfuGT" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IfuGU" role="37wK5m">
+              <node concept="liA8E" id="5jPBdK_vsV" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdK_vv8" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNF6V" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfuGw" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfuGV" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNF9Y" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfuGF" resolve="b" />
                 </node>
               </node>
@@ -2038,17 +2069,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="3HJTsBn443E" role="3cqZAp" />
-          <node concept="3clFbF" id="3HJTsBn443F" role="3cqZAp">
-            <node concept="2OqwBi" id="3HJTsBn443G" role="3clFbG">
-              <node concept="37vLTw" id="3HJTsBn443H" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNFji" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNFjj" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNFjk" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNFjl" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNFjm" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="3HJTsBn443I" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="3HJTsBn443J" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNFjn" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNFjo" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNFjp" role="37wK5m">
                   <ref role="3cqZAo" node="3HJTsBn443g" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="3HJTsBn443K" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNFjq" role="37wK5m">
                   <ref role="3cqZAo" node="3HJTsBn443w" resolve="b" />
                 </node>
               </node>
@@ -2210,33 +2251,53 @@
             </node>
           </node>
           <node concept="3vwNmj" id="7FuqS$4k214" role="3cqZAp">
-            <node concept="2OqwBi" id="7FuqS$4k5oX" role="3vwVQn">
-              <node concept="37vLTw" id="7FuqS$4k5oY" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
-              </node>
-              <node concept="liA8E" id="7FuqS$4k5oZ" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="37vLTw" id="7FuqS$4k5p0" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivyni3" resolve="c" />
+            <node concept="2OqwBi" id="5jPBdKNFB7" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNFB8" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNFB9" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
                 </node>
-                <node concept="37vLTw" id="7FuqS$4k5p1" role="37wK5m">
-                  <ref role="3cqZAo" node="4XqG8ivy_$I" resolve="d" />
+                <node concept="liA8E" id="5jPBdKNFBa" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
+              </node>
+              <node concept="liA8E" id="5jPBdKNFBb" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNFBc" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <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>
           </node>
           <node concept="3clFbH" id="7FuqS$4k1Wl" role="3cqZAp" />
-          <node concept="3clFbF" id="4XqG8ivynie" role="3cqZAp">
-            <node concept="2OqwBi" id="4XqG8ivynif" role="3clFbG">
-              <node concept="37vLTw" id="4XqG8ivynig" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNFL4" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNFL5" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNFL6" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNFL7" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNFL8" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4XqG8ivynih" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="4XqG8ivynii" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNFL9" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNFLa" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNFLb" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivynhQ" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="4XqG8ivyA_P" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNFLc" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivy$Me" resolve="b" />
                 </node>
               </node>
@@ -2270,16 +2331,26 @@
             </node>
           </node>
           <node concept="3vFxKo" id="4XqG8ivyGzs" role="3cqZAp">
-            <node concept="2OqwBi" id="4XqG8ivyBc1" role="3vFALc">
-              <node concept="37vLTw" id="4XqG8ivyBc2" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+            <node concept="2OqwBi" id="5jPBdKNG7d" role="3vFALc">
+              <node concept="2OqwBi" id="5jPBdKNG7e" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNG7f" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNG7g" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4XqG8ivyBc3" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="37vLTw" id="4XqG8ivyBl_" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNG7h" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNG7i" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNGcw" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivyni3" resolve="c" />
                 </node>
-                <node concept="37vLTw" id="4XqG8ivyBnr" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNGeg" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivy_$I" resolve="d" />
                 </node>
               </node>
@@ -2407,33 +2478,53 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0IfOk1" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0IfOfp" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfOfr" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IfOfs" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNGme" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNGmf" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNGmg" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNGmh" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNGmi" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfOft" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IfOfu" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNGmj" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNGmk" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNGml" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfNC5" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfOfv" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNGmm" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfNCg" resolve="b" />
                 </node>
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="1OShD0IfS$G" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfS$H" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IfS$I" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNGuA" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNGuB" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNGuC" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNGuD" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNGuE" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfS$J" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IfU27" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNGuF" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNGuG" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNGCr" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfNCg" resolve="b" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfSKy" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNGEd" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfOZy" resolve="c" />
                 </node>
               </node>
@@ -2522,16 +2613,26 @@
           </node>
           <node concept="3clFbH" id="1OShD0IfODl" role="3cqZAp" />
           <node concept="3vwNmj" id="1OShD0IfR23" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfR24" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IfR25" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+            <node concept="2OqwBi" id="5jPBdKNGS_" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNGSA" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNGSB" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNGSC" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfR26" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="37vLTw" id="1OShD0IfRhN" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNGSD" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNGSE" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNGZw" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfO_f" resolve="s" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfRkA" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNH1r" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfOGV" resolve="t" />
                 </node>
               </node>
@@ -2659,34 +2760,54 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbH" id="4XqG8ivylRD" role="3cqZAp" />
-          <node concept="3clFbF" id="4XqG8ivylRE" role="3cqZAp">
-            <node concept="2OqwBi" id="4XqG8ivylRF" role="3clFbG">
-              <node concept="37vLTw" id="4XqG8ivylRG" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbH" id="5jPBdKNHr8" role="3cqZAp" />
+          <node concept="3clFbF" id="5jPBdKNHhT" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNHhU" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNHhV" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNHhW" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNHhX" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4XqG8ivylRH" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="4XqG8ivylRI" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNHhY" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNHhZ" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNHH2" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylQZ" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="4XqG8ivylRJ" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNHIZ" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylRf" resolve="b" />
                 </node>
               </node>
             </node>
           </node>
-          <node concept="3clFbF" id="4XqG8ivylRK" role="3cqZAp">
-            <node concept="2OqwBi" id="4XqG8ivylRL" role="3clFbG">
-              <node concept="37vLTw" id="4XqG8ivylRM" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNH9r" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNH9s" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNH9t" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNH9u" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNH9v" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4XqG8ivylRN" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="4XqG8ivylRO" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNH9w" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNH9x" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNH9y" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylRf" resolve="b" />
                 </node>
-                <node concept="37vLTw" id="4XqG8ivylRP" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNH9z" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylRv" resolve="c" />
                 </node>
               </node>
@@ -2775,16 +2896,26 @@
           </node>
           <node concept="3clFbH" id="4XqG8ivylSf" role="3cqZAp" />
           <node concept="3vwNmj" id="4XqG8ivylSg" role="3cqZAp">
-            <node concept="2OqwBi" id="4XqG8ivylSh" role="3vwVQn">
-              <node concept="37vLTw" id="4XqG8ivylSi" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+            <node concept="2OqwBi" id="5jPBdKNHSB" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNHSC" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNHSD" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNHSE" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="4XqG8ivylSj" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="37vLTw" id="4XqG8ivylSk" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNHSF" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNHSG" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNHSH" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylS2" resolve="s" />
                 </node>
-                <node concept="37vLTw" id="4XqG8ivylSl" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNHSI" role="37wK5m">
                   <ref role="3cqZAo" node="4XqG8ivylS9" resolve="t" />
                 </node>
               </node>
@@ -2890,17 +3021,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0IfY4a" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0IfXZr" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfXZs" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IfXZt" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNHZ$" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNHZ_" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNHZA" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNHZB" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNHZC" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfXZu" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IfXZv" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNHZD" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNHZE" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNHZF" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfW$y" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfXZw" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNHZG" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfW$L" resolve="b" />
                 </node>
               </node>
@@ -2949,16 +3090,26 @@
           </node>
           <node concept="3clFbH" id="1OShD0IfYhY" role="3cqZAp" />
           <node concept="3vwNmj" id="1OShD0IfW_0" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IfW_1" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IfW_2" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+            <node concept="2OqwBi" id="5jPBdKNI3I" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNI3J" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNI3K" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNI3L" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IfW_3" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="37vLTw" id="1OShD0IfYy1" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNI3M" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNI3N" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNI3O" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfYmM" resolve="s" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IfY$$" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNI3P" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IfYmT" resolve="t" />
                 </node>
               </node>
@@ -3093,17 +3244,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0IgkRZ" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0IgkS0" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgkS1" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IgkS2" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNI6O" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNI6P" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNI6Q" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNI6R" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNI6S" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IgkS3" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IgkS4" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNI6T" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNI6U" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNI6V" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IgkRu" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IgkS5" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNI6W" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0IgkRM" resolve="b" />
                 </node>
               </node>
@@ -3115,28 +3276,37 @@
               <property role="3SKdUp" value="single node" />
             </node>
           </node>
-          <node concept="3clFbH" id="1OShD0IgkSm" role="3cqZAp" />
-          <node concept="3vwNmj" id="1OShD0IgkSn" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgkSo" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IgkSp" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3vwNmj" id="5jPBdKNIbX" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNIbY" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNIbZ" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNIc0" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNIc1" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IgkSq" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="1oi1Uc" id="1OShD0IgnVn" role="37wK5m">
-                  <node concept="1oi5UN" id="1OShD0IgnVo" role="1oi0x0">
-                    <node concept="1oi5Wm" id="1OShD0IgnVp" role="1ojpOf">
+              <node concept="liA8E" id="5jPBdKNIc2" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNIc3" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </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="1OShD0IgnVq" role="1oi5zu">
+                      <node concept="1oi5XN" id="5jPBdKNIhC" role="1oi5zu">
                         <property role="1oi5yK" value="bar" />
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="1OShD0Igo4R" role="37wK5m">
-                  <node concept="1oi5UN" id="677NV56wbOs" role="1oi0x0">
-                    <node concept="22Ky0T" id="677NV56wbOt" role="lGtFl">
-                      <node concept="37vLTw" id="1OShD0Igo4T" role="22Ky0K">
+                <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>
@@ -3145,29 +3315,38 @@
               </node>
             </node>
           </node>
-          <node concept="3clFbH" id="1OShD0Igm8U" role="3cqZAp" />
-          <node concept="3clFbH" id="1OShD0IglYB" role="3cqZAp" />
-          <node concept="3vwNmj" id="1OShD0IglYx" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IglYy" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IglYz" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbH" id="5jPBdKNIwy" role="3cqZAp" />
+          <node concept="3vwNmj" id="5jPBdKNInm" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNInn" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNIno" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNInp" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNInq" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IglY$" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="1oi1Uc" id="1OShD0Igoee" role="37wK5m">
-                  <node concept="1oi5UN" id="1OShD0Igoef" role="1oi0x0">
-                    <node concept="1oi5Wm" id="1OShD0Igoeg" role="1ojpOf">
+              <node concept="liA8E" id="5jPBdKNInr" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNIns" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <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="1OShD0Igoeh" role="1oi5zu">
+                      <node concept="1oi5XN" id="5jPBdKNIv4" role="1oi5zu">
                         <property role="1oi5yK" value="bazz" />
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="1OShD0Igonw" role="37wK5m">
-                  <node concept="1oi5UN" id="677NV56wbOy" role="1oi0x0">
-                    <node concept="22Ky0T" id="677NV56wbOz" role="lGtFl">
-                      <node concept="37vLTw" id="1OShD0Igony" role="22Ky0K">
+                <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>
@@ -3300,17 +3479,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0Ig2j5" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0IgaFM" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgaFN" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IgaFO" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNIG7" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNIG8" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNIG9" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNIGa" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNIGb" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IgaFP" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IgaFQ" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNIGc" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNIGd" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNIGe" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Ig2i$" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IgaFR" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNIGf" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Ig2iS" resolve="b" />
                 </node>
               </node>
@@ -3322,38 +3511,47 @@
               <property role="3SKdUp" value="*list* variable in the last position matches the _list_" />
             </node>
           </node>
-          <node concept="3clFbH" id="1OShD0IgaFw" role="3cqZAp" />
-          <node concept="3vwNmj" id="1OShD0IgaFq" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgaFr" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IgaFs" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3vwNmj" id="5jPBdKNIJK" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNIJL" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNIJM" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNIJN" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNIJO" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IgaFt" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="1oi1Uc" id="1OShD0IgmzL" role="37wK5m">
-                  <node concept="KCUsM" id="1OShD0IgmzM" role="1oi0x0">
-                    <node concept="1oi5UN" id="1OShD0IgmzN" role="KCVpo">
-                      <node concept="1oi5Wm" id="1OShD0IgmzO" role="1ojpOf">
+              <node concept="liA8E" id="5jPBdKNIJP" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNIJQ" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </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="1OShD0IgmzP" role="1oi5zu">
+                        <node concept="1oi5XN" id="5jPBdKNIPY" role="1oi5zu">
                           <property role="1oi5yK" value="bazz" />
                         </node>
                       </node>
                     </node>
-                    <node concept="1oi5UN" id="7nuzzkr2adA" role="KCVpo">
-                      <node concept="1oi5Wm" id="7nuzzkr2adB" role="1ojpOf">
+                    <node concept="1oi5UN" id="5jPBdKNIPZ" role="KCVpo">
+                      <node concept="1oi5Wm" id="5jPBdKNIQ0" role="1ojpOf">
                         <property role="TrG5h" value="name" />
-                        <node concept="1oi5XN" id="7nuzzkr2adC" role="1oi5zu">
+                        <node concept="1oi5XN" id="5jPBdKNIQ1" role="1oi5zu">
                           <property role="1oi5yK" value="bazzzz" />
                         </node>
                       </node>
                     </node>
                   </node>
                 </node>
-                <node concept="1oi1Uc" id="1OShD0IgmVf" role="37wK5m">
-                  <node concept="1oi5UN" id="677NV56wbOw" role="1oi0x0">
-                    <node concept="22Ky0T" id="677NV56wbOx" role="lGtFl">
-                      <node concept="37vLTw" id="1OShD0IgmVh" role="22Ky0K">
+                <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" />
                       </node>
                     </node>
@@ -3467,17 +3665,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0Ig9w$" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0Ig2j6" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0Ig2j7" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0Ig2j8" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNJ00" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNJ01" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNJ02" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNJ03" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNJ04" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0Ig2j9" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0Ig2ja" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNJ05" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNJ06" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNJ07" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Ig9w4" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0Ig2jb" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNJ08" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Ig9wj" resolve="b" />
                 </node>
               </node>
@@ -3489,21 +3697,30 @@
               <property role="3SKdUp" value="*list* variable in the last position matches the _list_" />
             </node>
           </node>
-          <node concept="3clFbH" id="1OShD0Ig2jr" role="3cqZAp" />
-          <node concept="3vwNmj" id="1OShD0Ig2js" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0Ig2jt" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0Ig2ju" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
-              </node>
-              <node concept="liA8E" id="1OShD0Ig2jv" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="1oi1Uc" id="1OShD0Igngn" role="37wK5m">
-                  <node concept="KCUsM" id="1OShD0Igngo" role="1oi0x0" />
+          <node concept="3vwNmj" id="5jPBdKNJ3l" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNJ3m" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNJ3n" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNJ3o" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
                 </node>
-                <node concept="1oi1Uc" id="1OShD0Ignoe" role="37wK5m">
-                  <node concept="1oi5UN" id="677NV56wbOk" role="1oi0x0">
-                    <node concept="22Ky0T" id="677NV56wbOl" role="lGtFl">
-                      <node concept="37vLTw" id="1OShD0Ignog" role="22Ky0K">
+                <node concept="liA8E" id="5jPBdKNJ3p" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
+              </node>
+              <node concept="liA8E" id="5jPBdKNJ3q" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNJ3r" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+                <node concept="1oi1Uc" id="5jPBdKNJ96" role="37wK5m">
+                  <node concept="KCUsM" id="5jPBdKNJ97" role="1oi0x0" />
+                </node>
+                <node concept="1oi1Uc" id="5jPBdKNJ98" role="37wK5m">
+                  <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>
@@ -3584,17 +3801,27 @@
             </node>
           </node>
           <node concept="3clFbH" id="1OShD0Igj1r" role="3cqZAp" />
-          <node concept="3clFbF" id="1OShD0IgiRF" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgiRG" role="3clFbG">
-              <node concept="37vLTw" id="1OShD0IgiRH" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
+          <node concept="3clFbF" id="5jPBdKNJfr" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNJfs" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdKNJft" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNJfu" role="2Oq$k0">
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                </node>
+                <node concept="liA8E" id="5jPBdKNJfv" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
               </node>
-              <node concept="liA8E" id="1OShD0IgiRI" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAlI6" resolve="tellUni" />
-                <node concept="37vLTw" id="1OShD0IgiRJ" role="37wK5m">
+              <node concept="liA8E" id="5jPBdKNJfw" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznPKO" resolve="tell" />
+                <node concept="10M0yZ" id="5jPBdKNJfx" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                </node>
+                <node concept="37vLTw" id="5jPBdKNJfy" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Igi9l" resolve="a" />
                 </node>
-                <node concept="37vLTw" id="1OShD0IgiRK" role="37wK5m">
+                <node concept="37vLTw" id="5jPBdKNJfz" role="37wK5m">
                   <ref role="3cqZAo" node="1OShD0Igi9u" resolve="b" />
                 </node>
               </node>
@@ -3606,21 +3833,30 @@
               <property role="3SKdUp" value="*list* variable in the last position matches the _list_" />
             </node>
           </node>
-          <node concept="3clFbH" id="1OShD0IgiRZ" role="3cqZAp" />
-          <node concept="3vwNmj" id="1OShD0IgiS0" role="3cqZAp">
-            <node concept="2OqwBi" id="1OShD0IgiS1" role="3vwVQn">
-              <node concept="37vLTw" id="1OShD0IgiS2" role="2Oq$k0">
-                <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
-              </node>
-              <node concept="liA8E" id="1OShD0IgiS3" role="2OqNvi">
-                <ref role="37wK5l" to="95zw:4OsiK2BAnTP" resolve="askUni" />
-                <node concept="1oi1Uc" id="1OShD0IgnvY" role="37wK5m">
-                  <node concept="KCUsM" id="1OShD0IgnvZ" role="1oi0x0" />
+          <node concept="3vwNmj" id="5jPBdKNJi$" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdKNJi_" role="3vwVQn">
+              <node concept="2OqwBi" id="5jPBdKNJiA" role="2Oq$k0">
+                <node concept="2YIFZM" id="5jPBdKNJiB" role="2Oq$k0">
+                  <ref role="37wK5l" to="rchb:5uFPQ7Bwt5n" resolve="current" />
+                  <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
                 </node>
-                <node concept="1oi1Uc" id="1OShD0IgnB0" role="37wK5m">
-                  <node concept="1oi5UN" id="677NV56wbOA" role="1oi0x0">
-                    <node concept="22Ky0T" id="677NV56wbOB" role="lGtFl">
-                      <node concept="37vLTw" id="1OShD0IgnB2" role="22Ky0K">
+                <node concept="liA8E" id="5jPBdKNJiC" role="2OqNvi">
+                  <ref role="37wK5l" to="rchb:5uFPQ7ClOzA" resolve="computingSession" />
+                </node>
+              </node>
+              <node concept="liA8E" id="5jPBdKNJiD" role="2OqNvi">
+                <ref role="37wK5l" to="qrld:4xBopTznHV5" resolve="ask" />
+                <node concept="10M0yZ" id="5jPBdKNJiE" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </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" />
                       </node>
                     </node>
@@ -3634,62 +3870,45 @@
     </node>
     <node concept="1KhYhu" id="1OShD0IftNv" role="1KhZu4">
       <node concept="3clFbS" id="1OShD0IftNw" role="2VODD2">
-        <node concept="3clFbF" id="1OShD0IftOp" role="3cqZAp">
-          <node concept="37vLTI" id="1OShD0IftOq" role="3clFbG">
-            <node concept="37vLTw" id="1OShD0IftOr" role="37vLTJ">
-              <ref role="3cqZAo" node="1OShD0Ift_O" resolve="constraintSystem" />
-            </node>
-            <node concept="2ShNRf" id="1OShD0IftOs" role="37vLTx">
-              <node concept="1pGfFk" id="1OShD0IftOt" role="2ShVmc">
-                <ref role="37wK5l" to="eifs:~ConstraintSystem.&lt;init&gt;()" resolve="ConstraintSystem" />
+        <node concept="3clFbF" id="5jPBdK_uPf" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_uPM" role="3clFbG">
+            <ref role="1Pybhc" node="5jPBdK_dIS" resolve="TestingEvaluationSession" />
+            <ref role="37wK5l" node="7ISVfSIf0j" resolve="init" />
+          </node>
+        </node>
+        <node concept="3clFbH" id="5jPBdK_uQ_" role="3cqZAp" />
+        <node concept="3clFbF" id="5jPBdK_uRs" role="3cqZAp">
+          <node concept="2OqwBi" id="5jPBdK_uYD" role="3clFbG">
+            <node concept="2OqwBi" id="5jPBdK_uUg" role="2Oq$k0">
+              <node concept="2YIFZM" id="5jPBdK_uTI" role="2Oq$k0">
+                <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+                <ref role="37wK5l" to="rchb:7ISVfSIwfH" resolve="newSession" />
               </node>
+              <node concept="liA8E" id="5jPBdK_uVI" role="2OqNvi">
+                <ref role="37wK5l" to="rchb:5uFPQ7Bwu9Q" resolve="withPredicates" />
+                <node concept="10M0yZ" id="5jPBdK_uXa" role="37wK5m">
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
+                  <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
+                </node>
+                <node concept="10M0yZ" id="5jPBdK_uXd" role="37wK5m">
+                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
+                </node>
+              </node>
+            </node>
+            <node concept="liA8E" id="5jPBdK_v1h" role="2OqNvi">
+              <ref role="37wK5l" to="rchb:7ISVfSIuSh" resolve="start" />
             </node>
           </node>
         </node>
-        <node concept="3clFbF" id="1OShD0IftOu" role="3cqZAp">
-          <node concept="2OqwBi" id="1OShD0IftOv" role="3clFbG">
-            <node concept="37vLTw" id="1OShD0IftOw" role="2Oq$k0">
-              <ref role="3cqZAo" node="1OShD0Ift_O" resolve="constraintSystem" />
-            </node>
-            <node concept="liA8E" id="1OShD0IftOx" role="2OqNvi">
-              <ref role="37wK5l" to="eifs:~ConstraintSystem.setQueuing(boolean):void" resolve="setQueuing" />
-              <node concept="3clFbT" id="1OShD0IftOy" role="37wK5m">
-                <property role="3clFbU" value="false" />
-              </node>
-            </node>
-          </node>
-        </node>
-        <node concept="3clFbF" id="1OShD0IftOz" role="3cqZAp">
-          <node concept="37vLTI" id="1OShD0IftO$" role="3clFbG">
-            <node concept="2ShNRf" id="1OShD0IftO_" role="37vLTx">
-              <node concept="1pGfFk" id="1OShD0IftOA" role="2ShVmc">
-                <ref role="37wK5l" to="95zw:5p8T3QHGKJ7" resolve="UnificationSolverImpl" />
-                <node concept="2OqwBi" id="5uFPQ7CmmaS" role="37wK5m">
-                  <node concept="2YIFZM" id="5uFPQ7CmmaT" role="2Oq$k0">
-                    <ref role="1Pybhc" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
-                    <ref role="37wK5l" to="qrld:6Kcfpq7BWKD" resolve="with" />
-                    <node concept="10M0yZ" id="5uFPQ7CmmaU" role="37wK5m">
-                      <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
-                      <ref role="3cqZAo" to="oy3s:5uFPQ7C23RV" resolve="EQ_SYM" />
-                    </node>
-                    <node concept="10M0yZ" id="5uFPQ7CmmaV" role="37wK5m">
-                      <ref role="3cqZAo" to="oy3s:5uFPQ7C29mw" resolve="UNI_SYM" />
-                      <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
-                    </node>
-                  </node>
-                  <node concept="liA8E" id="5uFPQ7CmmaW" role="2OqNvi">
-                    <ref role="37wK5l" to="qrld:6Kcfpq7Cgrc" resolve="newSession" />
-                  </node>
-                </node>
-                <node concept="37vLTw" id="1OShD0IftOB" role="37wK5m">
-                  <ref role="3cqZAo" node="1OShD0Ift_O" resolve="constraintSystem" />
-                </node>
-                <node concept="10Nm6u" id="5uFPQ7Cmmhq" role="37wK5m" />
-              </node>
-            </node>
-            <node concept="37vLTw" id="1OShD0IftOC" role="37vLTJ">
-              <ref role="3cqZAo" node="1OShD0Ift_R" resolve="unificationSolver" />
-            </node>
+      </node>
+    </node>
+    <node concept="1KhZuU" id="5jPBdKNDUW" role="1KhZu3">
+      <node concept="3clFbS" id="5jPBdKNDUX" role="2VODD2">
+        <node concept="3clFbF" id="5jPBdK_M6G" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_M7s" role="3clFbG">
+            <ref role="37wK5l" node="5jPBdK_KqB" resolve="deinit" />
+            <ref role="1Pybhc" node="5jPBdK_dIS" resolve="TestingEvaluationSession" />
           </node>
         </node>
       </node>
@@ -4546,5 +4765,396 @@
       </node>
     </node>
   </node>
+  <node concept="312cEu" id="5jPBdK_dIS">
+    <property role="TrG5h" value="TestingEvaluationSession" />
+    <node concept="2tJIrI" id="5jPBdK_KTs" role="jymVt" />
+    <node concept="Wx3nA" id="5jPBdK_KfB" role="jymVt">
+      <property role="3TUv4t" value="true" />
+      <property role="TrG5h" value="ourBackend" />
+      <node concept="3Tm6S6" id="5jPBdK_Kfz" role="1B3o_S" />
+      <node concept="3uibUv" id="5jPBdK_Kf$" role="1tU5fm">
+        <ref role="3uigEE" node="5jPBdK_dKd" resolve="TestingEvaluationSession.Backend" />
+      </node>
+      <node concept="2ShNRf" id="5jPBdK_Kf_" role="33vP2m">
+        <node concept="HV5vD" id="5jPBdK_KfA" role="2ShVmc">
+          <ref role="HV5vE" node="5jPBdK_dKd" resolve="TestingEvaluationSession.Backend" />
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_s6v" role="jymVt" />
+    <node concept="Wx3nA" id="5jPBdK_nJi" role="jymVt">
+      <property role="TrG5h" value="INSTANCE" />
+      <node concept="3Tm6S6" id="5jPBdK_nJk" role="1B3o_S" />
+      <node concept="3uibUv" id="5jPBdK_nNn" role="1tU5fm">
+        <ref role="3uigEE" node="5jPBdK_dIS" resolve="TestingEvaluationSession" />
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_nzw" role="jymVt" />
+    <node concept="2YIFZL" id="7ISVfSIf0j" role="jymVt">
+      <property role="TrG5h" value="init" />
+      <node concept="3cqZAl" id="7ISVfSIf0l" role="3clF45" />
+      <node concept="3Tm1VV" id="7ISVfSIf0m" role="1B3o_S" />
+      <node concept="3clFbS" id="7ISVfSIf0n" role="3clF47">
+        <node concept="3clFbF" id="7ISVfSIf2T" role="3cqZAp">
+          <node concept="2YIFZM" id="7ISVfSIf4g" role="3clFbG">
+            <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+            <ref role="37wK5l" to="rchb:5uFPQ7Bwt$y" resolve="setBackend" />
+            <node concept="37vLTw" id="5jPBdK_KfE" role="37wK5m">
+              <ref role="3cqZAo" node="5jPBdK_KfB" resolve="ourBackend" />
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_KJw" role="jymVt" />
+    <node concept="2YIFZL" id="5jPBdK_KqB" role="jymVt">
+      <property role="TrG5h" value="deinit" />
+      <node concept="3cqZAl" id="5jPBdK_KqC" role="3clF45" />
+      <node concept="3Tm1VV" id="5jPBdK_KqD" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_KqE" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_KqF" role="3cqZAp">
+          <node concept="2YIFZM" id="5jPBdK_KEq" role="3clFbG">
+            <ref role="37wK5l" to="rchb:5jPBdK_JeZ" resolve="clearBackend" />
+            <ref role="1Pybhc" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+            <node concept="37vLTw" id="5jPBdK_KEr" role="37wK5m">
+              <ref role="3cqZAo" node="5jPBdK_KfB" resolve="ourBackend" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbF" id="5jPBdK_NAE" role="3cqZAp">
+          <node concept="37vLTI" id="5jPBdK_NDg" role="3clFbG">
+            <node concept="10Nm6u" id="5jPBdK_NDW" role="37vLTx" />
+            <node concept="37vLTw" id="5jPBdK_NAC" role="37vLTJ">
+              <ref role="3cqZAo" node="5jPBdK_nJi" resolve="INSTANCE" />
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_dK1" role="jymVt" />
+    <node concept="3clFbW" id="5jPBdK_qM0" role="jymVt">
+      <node concept="3cqZAl" id="5jPBdK_qM2" role="3clF45" />
+      <node concept="3Tm6S6" id="5jPBdK_rSe" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_qM4" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_qYH" role="3cqZAp">
+          <node concept="37vLTI" id="5jPBdK_qYJ" role="3clFbG">
+            <node concept="2OqwBi" id="5jPBdK_qYN" role="37vLTJ">
+              <node concept="Xjq3P" id="5jPBdK_qYQ" role="2Oq$k0" />
+              <node concept="2OwXpG" id="5jPBdK_qYM" role="2OqNvi">
+                <ref role="2Oxat5" node="5jPBdK_qYD" resolve="computingSession" />
+              </node>
+            </node>
+            <node concept="37vLTw" id="5jPBdK_qYR" role="37vLTx">
+              <ref role="3cqZAo" node="5jPBdK_qV5" resolve="computingSession" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="37vLTG" id="5jPBdK_qV5" role="3clF46">
+        <property role="TrG5h" value="computingSession" />
+        <node concept="3uibUv" id="5jPBdK_qV4" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_qFR" role="jymVt" />
+    <node concept="3clFb_" id="5jPBdK_dWv" role="jymVt">
+      <property role="TrG5h" value="computingTracer" />
+      <property role="1EzhhJ" value="false" />
+      <node concept="3uibUv" id="5jPBdK_dWw" role="3clF45">
+        <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
+      </node>
+      <node concept="3Tm1VV" id="5jPBdK_dWx" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_dWz" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_dW_" role="3cqZAp">
+          <node concept="10Nm6u" id="5jPBdK_dW$" role="3clFbG" />
+        </node>
+      </node>
+    </node>
+    <node concept="3clFb_" id="5jPBdK_dWA" role="jymVt">
+      <property role="TrG5h" value="computingSession" />
+      <property role="1EzhhJ" value="false" />
+      <node concept="3uibUv" id="5jPBdK_dWB" role="3clF45">
+        <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+      </node>
+      <node concept="3Tm1VV" id="5jPBdK_dWC" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_dWE" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_r6i" role="3cqZAp">
+          <node concept="37vLTw" id="5jPBdK_r6h" role="3clFbG">
+            <ref role="3cqZAo" node="5jPBdK_qYD" resolve="computingSession" />
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="3clFb_" id="5jPBdK_dX1" role="jymVt">
+      <property role="TrG5h" value="constraintSymbols" />
+      <property role="1EzhhJ" value="false" />
+      <node concept="3uibUv" id="5jPBdK_dX2" role="3clF45">
+        <ref role="3uigEE" to="wyt6:~Iterable" resolve="Iterable" />
+        <node concept="3uibUv" id="5jPBdK_dX3" role="11_B2D">
+          <ref role="3uigEE" to="qrld:54i3FxcZHHF" resolve="ConstraintSymbol" />
+        </node>
+      </node>
+      <node concept="3Tm1VV" id="5jPBdK_dX4" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_dX6" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_dX8" role="3cqZAp">
+          <node concept="10Nm6u" id="5jPBdK_dX7" role="3clFbG" />
+        </node>
+      </node>
+    </node>
+    <node concept="3clFb_" id="5jPBdK_dX9" role="jymVt">
+      <property role="TrG5h" value="constraintOccurrences" />
+      <property role="1EzhhJ" value="false" />
+      <node concept="3uibUv" id="5jPBdK_dXa" role="3clF45">
+        <ref role="3uigEE" to="wyt6:~Iterable" resolve="Iterable" />
+        <node concept="3uibUv" id="5jPBdK_dXb" role="11_B2D">
+          <ref role="3uigEE" to="qrld:5uFPQ7BZac$" resolve="ConstraintOccurrence" />
+        </node>
+      </node>
+      <node concept="3Tm1VV" id="5jPBdK_dXc" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_dXe" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_dXg" role="3cqZAp">
+          <node concept="10Nm6u" id="5jPBdK_dXf" role="3clFbG" />
+        </node>
+      </node>
+    </node>
+    <node concept="3clFb_" id="5jPBdK_dXh" role="jymVt">
+      <property role="TrG5h" value="constraintOccurrences" />
+      <property role="1EzhhJ" value="false" />
+      <node concept="37vLTG" id="5jPBdK_dXi" role="3clF46">
+        <property role="TrG5h" value="symbol" />
+        <node concept="3uibUv" id="5jPBdK_dXj" role="1tU5fm">
+          <ref role="3uigEE" to="qrld:54i3FxcZHHF" resolve="ConstraintSymbol" />
+        </node>
+      </node>
+      <node concept="3uibUv" id="5jPBdK_dXk" role="3clF45">
+        <ref role="3uigEE" to="wyt6:~Iterable" resolve="Iterable" />
+        <node concept="3uibUv" id="5jPBdK_dXl" role="11_B2D">
+          <ref role="3uigEE" to="qrld:5uFPQ7BZac$" resolve="ConstraintOccurrence" />
+        </node>
+      </node>
+      <node concept="3Tm1VV" id="5jPBdK_dXm" role="1B3o_S" />
+      <node concept="3clFbS" id="5jPBdK_dXo" role="3clF47">
+        <node concept="3clFbF" id="5jPBdK_dXq" role="3cqZAp">
+          <node concept="10Nm6u" id="5jPBdK_dXp" role="3clFbG" />
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+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_dW3" role="jymVt" />
+    <node concept="312cEu" id="5jPBdK_mRo" role="jymVt">
+      <property role="2bfB8j" value="false" />
+      <property role="TrG5h" value="Config" />
+      <node concept="3Tm1VV" id="5jPBdK_mRp" role="1B3o_S" />
+      <node concept="3uibUv" id="5jPBdK_n1a" role="1zkMxy">
+        <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+      </node>
+      <node concept="3clFb_" id="5jPBdK_npi" role="jymVt">
+        <property role="TrG5h" value="withPredicates" />
+        <property role="1EzhhJ" value="false" />
+        <node concept="37vLTG" id="5jPBdK_npj" role="3clF46">
+          <property role="TrG5h" value="predicateSymbols" />
+          <node concept="8X2XB" id="5jPBdK_npk" role="1tU5fm">
+            <node concept="3uibUv" id="5jPBdK_npl" role="8Xvag">
+              <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
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+        <node concept="3uibUv" id="5jPBdK_npm" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_npn" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_npp" role="3clF47">
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+            <node concept="37vLTI" id="5jPBdK_qdI" role="3clFbG">
+              <node concept="2OqwBi" id="5jPBdK_qdM" role="37vLTJ">
+                <node concept="Xjq3P" id="5jPBdK_qdP" role="2Oq$k0" />
+                <node concept="2OwXpG" id="5jPBdK_qdL" role="2OqNvi">
+                  <ref role="2Oxat5" node="5jPBdK_qdB" resolve="predicateSymbols" />
+                </node>
+              </node>
+              <node concept="37vLTw" id="5jPBdK_qdQ" role="37vLTx">
+                <ref role="3cqZAo" node="5jPBdK_npj" resolve="predicateSymbols" />
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbF" id="5jPBdK_rac" role="3cqZAp">
+            <node concept="Xjq3P" id="5jPBdK_raa" role="3clFbG" />
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+        </node>
+      </node>
+      <node concept="3clFb_" id="5jPBdK_nps" role="jymVt">
+        <property role="TrG5h" value="withTrace" />
+        <property role="1EzhhJ" value="false" />
+        <node concept="37vLTG" id="5jPBdK_npt" role="3clF46">
+          <property role="TrG5h" value="computingTracer" />
+          <node concept="3uibUv" id="5jPBdK_npu" role="1tU5fm">
+            <ref role="3uigEE" to="qrld:24Vro6cQnrj" resolve="ComputingTracer" />
+          </node>
+        </node>
+        <node concept="3uibUv" id="5jPBdK_npv" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_npw" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_npy" role="3clF47">
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+            <node concept="10Nm6u" id="5jPBdK_npz" role="3clFbG" />
+          </node>
+        </node>
+      </node>
+      <node concept="3clFb_" id="5jPBdK_np_" role="jymVt">
+        <property role="TrG5h" value="withParam" />
+        <property role="1EzhhJ" value="false" />
+        <node concept="37vLTG" id="5jPBdK_npA" role="3clF46">
+          <property role="TrG5h" value="key" />
+          <node concept="17QB3L" id="5jPBdK_npB" role="1tU5fm" />
+        </node>
+        <node concept="37vLTG" id="5jPBdK_npC" role="3clF46">
+          <property role="TrG5h" value="param" />
+          <node concept="3uibUv" id="5jPBdK_npD" role="1tU5fm">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+        <node concept="3uibUv" id="5jPBdK_npE" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_npF" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_npH" role="3clF47">
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+            <node concept="10Nm6u" id="5jPBdK_npI" role="3clFbG" />
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+        </node>
+      </node>
+      <node concept="3clFb_" id="5jPBdK_npK" role="jymVt">
+        <property role="TrG5h" value="start" />
+        <property role="1EzhhJ" value="false" />
+        <node concept="3uibUv" id="5jPBdK_npL" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_npM" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_npO" role="3clF47">
+          <node concept="3cpWs8" id="5jPBdK_DfG" role="3cqZAp">
+            <node concept="3cpWsn" id="5jPBdK_DfH" role="3cpWs9">
+              <property role="TrG5h" value="csession" />
+              <node concept="3uibUv" id="5jPBdK_DfB" role="1tU5fm">
+                <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+              </node>
+              <node concept="2OqwBi" id="5jPBdK_DfI" role="33vP2m">
+                <node concept="2YIFZM" id="5jPBdK_DfJ" role="2Oq$k0">
+                  <ref role="37wK5l" to="qrld:6Kcfpq7BWKD" resolve="with" />
+                  <ref role="1Pybhc" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+                  <node concept="37vLTw" id="5jPBdK_DfK" role="37wK5m">
+                    <ref role="3cqZAo" node="5jPBdK_qdB" resolve="predicateSymbols" />
+                  </node>
+                </node>
+                <node concept="liA8E" id="5jPBdK_DfL" role="2OqNvi">
+                  <ref role="37wK5l" to="qrld:6Kcfpq7Cgrc" resolve="newSession" />
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbF" id="5jPBdK_B63" role="3cqZAp">
+            <node concept="2OqwBi" id="5jPBdK_Bcd" role="3clFbG">
+              <node concept="2ShNRf" id="5jPBdK_BqZ" role="2Oq$k0">
+                <node concept="1pGfFk" id="5jPBdK_Br0" role="2ShVmc">
+                  <ref role="37wK5l" to="95zw:5mr7UHch7og" resolve="Symbols" />
+                  <node concept="37vLTw" id="5jPBdK_DCR" role="37wK5m">
+                    <ref role="3cqZAo" node="5jPBdK_DfH" resolve="csession" />
+                  </node>
+                  <node concept="10Nm6u" id="5jPBdK_DIc" role="37wK5m" />
+                </node>
+              </node>
+              <node concept="liA8E" id="5jPBdK_Bhd" role="2OqNvi">
+                <ref role="37wK5l" to="95zw:5jPBdK__lx" resolve="registerSymbols" />
+                <node concept="2OqwBi" id="5jPBdK_Bie" role="37wK5m">
+                  <node concept="Xjq3P" id="5jPBdK_DL6" role="2Oq$k0" />
+                  <node concept="2OwXpG" id="5jPBdK_Ep_" role="2OqNvi">
+                    <ref role="2Oxat5" node="5jPBdK_qdB" resolve="predicateSymbols" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbF" id="5jPBdK_p5i" role="3cqZAp">
+            <node concept="37vLTI" id="5jPBdK_p7U" role="3clFbG">
+              <node concept="37vLTw" id="5jPBdK_p5h" role="37vLTJ">
+                <ref role="3cqZAo" node="5jPBdK_nJi" resolve="INSTANCE" />
+              </node>
+              <node concept="2ShNRf" id="5jPBdK_pxU" role="37vLTx">
+                <node concept="1pGfFk" id="5jPBdK_qS9" role="2ShVmc">
+                  <ref role="37wK5l" node="5jPBdK_qM0" resolve="TestingEvaluationSession" />
+                  <node concept="37vLTw" id="5jPBdK_DfM" role="37wK5m">
+                    <ref role="3cqZAo" node="5jPBdK_DfH" resolve="csession" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="312cEg" id="5jPBdK_qdB" role="jymVt">
+        <property role="TrG5h" value="predicateSymbols" />
+        <node concept="3Tm6S6" id="5jPBdK_qdC" role="1B3o_S" />
+        <node concept="10Q1$e" id="5jPBdK_qn0" role="1tU5fm">
+          <node concept="3uibUv" id="5jPBdK_qdF" role="10Q1$1">
+            <ref role="3uigEE" to="qrld:5uFPQ7B$$3f" resolve="PredicateSymbol" />
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="5jPBdK_mO3" role="jymVt" />
+    <node concept="312cEu" id="5jPBdK_dKd" role="jymVt">
+      <property role="2bfB8j" value="false" />
+      <property role="TrG5h" value="Backend" />
+      <node concept="3Tm1VV" id="5jPBdK_dKe" role="1B3o_S" />
+      <node concept="3uibUv" id="5jPBdK_dR3" role="EKbjA">
+        <ref role="3uigEE" to="rchb:5uFPQ7BwtoR" resolve="EvaluationSession.Backend" />
+      </node>
+      <node concept="2tJIrI" id="5jPBdK_dUF" role="jymVt" />
+      <node concept="3clFb_" id="5jPBdK_dRk" role="jymVt">
+        <property role="1EzhhJ" value="false" />
+        <property role="TrG5h" value="current" />
+        <node concept="3uibUv" id="5jPBdK_dRl" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_dRm" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_dRo" role="3clF47">
+          <node concept="3clFbF" id="5jPBdK_nTT" role="3cqZAp">
+            <node concept="37vLTw" id="5jPBdK_nTS" role="3clFbG">
+              <ref role="3cqZAo" node="5jPBdK_nJi" resolve="INSTANCE" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="2tJIrI" id="5jPBdK_dTD" role="jymVt" />
+      <node concept="3clFb_" id="5jPBdK_dSh" role="jymVt">
+        <property role="1EzhhJ" value="false" />
+        <property role="TrG5h" value="createConfig" />
+        <node concept="3uibUv" id="5jPBdK_dSi" role="3clF45">
+          <ref role="3uigEE" to="rchb:5uFPQ7Bwt8Z" resolve="EvaluationSession.Config" />
+        </node>
+        <node concept="3Tm1VV" id="5jPBdK_dSj" role="1B3o_S" />
+        <node concept="3clFbS" id="5jPBdK_dSl" role="3clF47">
+          <node concept="3clFbF" id="5jPBdK_nWq" role="3cqZAp">
+            <node concept="2ShNRf" id="5jPBdK_nWo" role="3clFbG">
+              <node concept="HV5vD" id="5jPBdK_p0f" role="2ShVmc">
+                <ref role="HV5vE" node="5jPBdK_mRo" resolve="TestingEvaluationSession.Config" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="3Tm1VV" id="5jPBdK_dIT" role="1B3o_S" />
+    <node concept="3uibUv" id="5jPBdK_dJd" role="1zkMxy">
+      <ref role="3uigEE" to="rchb:5uFPQ7BvN_d" resolve="EvaluationSession" />
+    </node>
+    <node concept="312cEg" id="5jPBdK_qYD" role="jymVt">
+      <property role="TrG5h" value="computingSession" />
+      <node concept="3Tm6S6" id="5jPBdK_qYE" role="1B3o_S" />
+      <node concept="3uibUv" id="5jPBdK_qYG" role="1tU5fm">
+        <ref role="3uigEE" to="qrld:6Kcfpq7B0b0" resolve="ComputingSession" />
+      </node>
+    </node>
+  </node>
 </model>