diff --git a/reactor/API/pom.xml b/reactor/API/pom.xml
index 41aff01b..4cf73c2a 100644
--- a/reactor/API/pom.xml
+++ b/reactor/API/pom.xml
@@ -4,29 +4,18 @@
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
-    <artifactId>api</artifactId>
-    <packaging>jar</packaging>
-
     <parent>
         <groupId>jetbrains.mps.logic.reactor</groupId>
         <artifactId>main</artifactId>
-        <version>${reactor.version}</version>
+        <version>0.1</version>
         <relativePath>..</relativePath>
     </parent>
 
+    <artifactId>api</artifactId>
+    <packaging>jar</packaging>
+
     <build>
         <sourceDirectory>${basedir}/src/</sourceDirectory>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <version>${maven.version}</version>
-                <configuration>
-                    <source>1.6</source>
-                    <target>1.6</target>
-                </configuration>
-            </plugin>
-        </plugins>
     </build>
 
 </project>
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractConstraint.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractConstraint.java
index ec2a3582..0e90337f 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractConstraint.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractConstraint.java
@@ -2,10 +2,12 @@ package jetbrains.mps.logic.reactor.constraint;
 
 /*Generated by MPS */
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Arrays;
+import java.util.List;
 import java.util.ArrayList;
+import jetbrains.mps.logic.reactor.logical.LogicalPattern;
 
 public class AbstractConstraint implements Constraint {
 
@@ -18,14 +20,18 @@ public class AbstractConstraint implements Constraint {
     return symbol;
   }
 
-  public List<Object> arguments() {
+  public Collection<?> arguments() {
     return Collections.unmodifiableList(Arrays.asList(arguments));
   }
 
   public List<Class<?>> argumentTypes() {
     ArrayList<Class<?>> types = new ArrayList<Class<?>>(arguments.length);
     for (Object arg : arguments) {
-      types.add(arg.getClass());
+      if (arg instanceof LogicalPattern) {
+        types.add(((LogicalPattern) arg).type());
+      } else {
+        types.add(arg.getClass());
+      }
     }
     return types;
   }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractPredicate.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractPredicate.java
index 1a3a19b9..86204d78 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractPredicate.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AbstractPredicate.java
@@ -2,7 +2,7 @@ package jetbrains.mps.logic.reactor.constraint;
 
 /*Generated by MPS */
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Arrays;
 
@@ -13,7 +13,7 @@ public abstract class AbstractPredicate implements Predicate {
   }
 
   @Override
-  public List<Object> arguments() {
+  public Collection<?> arguments() {
     return Collections.unmodifiableList(Arrays.asList(arguments));
   }
 
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AndItem.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AndItem.java
index c26c080f..1eb01bcc 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AndItem.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/AndItem.java
@@ -2,12 +2,12 @@ package jetbrains.mps.logic.reactor.constraint;
 
 /*Generated by MPS */
 
-import java.util.List;
+import java.util.Collection;
 
 public interface AndItem {
 
   public Symbol symbol();
 
-  public List<Object> arguments();
+  public Collection<?> arguments();
 
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ComputingTracer.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ComputingTracer.java
index 54c949d1..45670cf4 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ComputingTracer.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ComputingTracer.java
@@ -9,6 +9,22 @@ public interface ComputingTracer {
 
   public void askFailure(PredicateSymbol predicateSymbol, Object... args);
 
+  public void ask(PredicateSymbol predicateSymbol, Object... args);
+
+  public void tell(Symbol symbol, Object... args);
+
   public void reportFailure(String message);
 
+  public static final ComputingTracer NULL = new ComputingTracer() {
+    public void askSuccess(PredicateSymbol predicateSymbol, Object... args) {
+    }
+    public void askFailure(PredicateSymbol predicateSymbol, Object... args) {
+    }
+    public void ask(PredicateSymbol predicateSymbol, Object... args) {
+    }
+    public void tell(Symbol symbol, Object... args) {
+    }
+    public void reportFailure(String message) {
+    }
+  };
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ConstraintOccurrence.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ConstraintOccurrence.java
index 3147b931..88b677ea 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ConstraintOccurrence.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/ConstraintOccurrence.java
@@ -2,12 +2,12 @@ package jetbrains.mps.logic.reactor.constraint;
 
 /*Generated by MPS */
 
-import java.util.List;
+import java.util.Collection;
 
 public interface ConstraintOccurrence {
 
   public Constraint constraint();
 
-  public List<Object> arguments();
+  public Collection<?> arguments();
 
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/SessionSolver.java b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/SessionSolver.java
index 5b67c7cd..ca58b675 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/SessionSolver.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/SessionSolver.java
@@ -11,20 +11,23 @@ import java.util.HashMap;
 public abstract class SessionSolver implements Instructible, Queryable {
 
   public void init(PredicateSymbol... predicateSymbols) {
-    registerSymbols(null, predicateSymbols);
+    registerSymbols(predicateSymbols);
   }
 
   public void init(ComputingTracer computingTracer, PredicateSymbol... predicateSymbols) {
-    registerSymbols(computingTracer, predicateSymbols);
+    tracer = computingTracer;
+    init(predicateSymbols);
   }
 
   @Override
   public boolean ask(PredicateSymbol predicateSymbol, Object... arg) {
+    tracer.ask(predicateSymbol, arg);
     return solver(predicateSymbol).ask(predicateSymbol, arg);
   }
 
   @Override
   public void tell(Symbol symbol, Object... arg) {
+    tracer.tell(symbol, arg);
     handler(symbol).tell(symbol, arg);
   }
 
@@ -50,9 +53,9 @@ public abstract class SessionSolver implements Instructible, Queryable {
     return solver((PredicateSymbol) symbol);
   }
 
-  private void registerSymbols(ComputingTracer computingTracer, PredicateSymbol... predicateSymbols) {
+  private void registerSymbols(PredicateSymbol... predicateSymbols) {
     for (PredicateSymbol symbol : predicateSymbols) {
-      registerSymbol(symbol, computingTracer);
+      registerSymbol(symbol, tracer);
     }
   }
 
@@ -64,4 +67,5 @@ public abstract class SessionSolver implements Instructible, Queryable {
   }
 
   private Map<PredicateSymbol, Queryable> solvers = new HashMap<PredicateSymbol, Queryable>();
+  private ComputingTracer tracer = ComputingTracer.NULL;
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/trace.info b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/trace.info
index 58ee54ff..57c07954 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/constraint/trace.info
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/constraint/trace.info
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <debug-info>
+  <concept fqn="jetbrains.mps.baseLanguage.structure.BlockStatement" />
   <concept fqn="jetbrains.mps.baseLanguage.structure.ConstructorDeclaration" />
   <concept fqn="jetbrains.mps.baseLanguage.structure.ExpressionStatement" />
   <concept fqn="jetbrains.mps.baseLanguage.structure.FieldDeclaration" />
@@ -15,9 +16,22 @@
   <concept fqn="jetbrains.mps.baseLanguage.structure.ThrowStatement" />
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/2394628030058821331">
     <file name="ComputingTracer.java">
-      <node id="2394628030058889702" at="8,0,9,0" concept="5" trace="askSuccess#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
-      <node id="2394628030058891476" at="10,0,11,0" concept="5" trace="askFailure#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
-      <node id="8344829839210112466" at="12,0,13,0" concept="5" trace="reportFailure#(Ljava/lang/String;)V" />
+      <node id="2394628030058889702" at="8,0,9,0" concept="6" trace="askSuccess#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="2394628030058891476" at="10,0,11,0" concept="6" trace="askFailure#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="7375810237849470390" at="12,0,13,0" concept="6" trace="ask#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="7375810237849456124" at="14,0,15,0" concept="6" trace="tell#(Ljetbrains/mps/logic/reactor/constraint/Symbol;null)V" />
+      <node id="8344829839210112466" at="16,0,17,0" concept="6" trace="reportFailure#(Ljava/lang/String;)V" />
+      <node id="5160444407776325515" at="19,0,21,0" concept="6" trace="askSuccess#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="5160444407776325526" at="21,0,23,0" concept="6" trace="askFailure#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="5160444407776325537" at="23,0,25,0" concept="6" trace="ask#(Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;null)V" />
+      <node id="5160444407776325548" at="25,0,27,0" concept="6" trace="tell#(Ljetbrains/mps/logic/reactor/constraint/Symbol;null)V" />
+      <node id="5160444407776325559" at="27,0,29,0" concept="6" trace="reportFailure#(Ljava/lang/String;)V" />
+      <node id="5160444407776320865" at="18,0,30,0" concept="10" trace="NULL" />
+      <scope id="5160444407776325524" at="19,77,19,77" />
+      <scope id="5160444407776325535" at="21,77,21,77" />
+      <scope id="5160444407776325546" at="23,70,23,70" />
+      <scope id="5160444407776325557" at="25,53,25,53" />
+      <scope id="5160444407776325565" at="27,47,27,47" />
       <scope id="2394628030058889702" at="8,0,9,0">
         <var name="args" id="2394628030058890766" />
         <var name="predicateSymbol" id="2394628030058890707" />
@@ -26,20 +40,48 @@
         <var name="args" id="2394628030058891479" />
         <var name="predicateSymbol" id="2394628030058891477" />
       </scope>
-      <scope id="8344829839210112466" at="12,0,13,0">
+      <scope id="7375810237849470390" at="12,0,13,0">
+        <var name="args" id="7375810237849470393" />
+        <var name="predicateSymbol" id="7375810237849470391" />
+      </scope>
+      <scope id="7375810237849456124" at="14,0,15,0">
+        <var name="args" id="7375810237849456127" />
+        <var name="symbol" id="7375810237849456125" />
+      </scope>
+      <scope id="8344829839210112466" at="16,0,17,0">
         <var name="message" id="8344829839210112700" />
       </scope>
-      <unit id="2394628030058821331" at="6,0,15,0" name="jetbrains.mps.logic.reactor.constraint.ComputingTracer" />
+      <scope id="5160444407776325515" at="19,0,21,0">
+        <var name="args" id="5160444407776325518" />
+        <var name="predicateSymbol" id="5160444407776325516" />
+      </scope>
+      <scope id="5160444407776325526" at="21,0,23,0">
+        <var name="args" id="5160444407776325529" />
+        <var name="predicateSymbol" id="5160444407776325527" />
+      </scope>
+      <scope id="5160444407776325537" at="23,0,25,0">
+        <var name="args" id="5160444407776325540" />
+        <var name="predicateSymbol" id="5160444407776325538" />
+      </scope>
+      <scope id="5160444407776325548" at="25,0,27,0">
+        <var name="args" id="5160444407776325551" />
+        <var name="symbol" id="5160444407776325549" />
+      </scope>
+      <scope id="5160444407776325559" at="27,0,29,0">
+        <var name="message" id="5160444407776325560" />
+      </scope>
+      <unit id="5160444407776325513" at="18,49,29,3" name="jetbrains.mps.logic.reactor.constraint.ComputingTracer$1" />
+      <unit id="2394628030058821331" at="6,0,31,0" name="jetbrains.mps.logic.reactor.constraint.ComputingTracer" />
     </file>
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/5841747851381496683">
     <file name="ConstraintSymbol.java">
-      <node id="5841747851381535271" at="11,63,12,43" concept="7" />
-      <node id="6317379717814129922" at="15,49,16,21" concept="11" />
-      <node id="5841747851383361011" at="20,28,21,32" concept="7" />
-      <node id="5841747851381533067" at="11,0,14,0" concept="10" trace="symbol#(Ljava/lang/String;I)Ljetbrains/mps/logic/reactor/constraint/ConstraintSymbol;" />
-      <node id="5841747851381516224" at="15,0,18,0" concept="0" trace="ConstraintSymbol#(Ljava/lang/String;I)V" />
-      <node id="5841747851383347181" at="19,0,23,0" concept="5" trace="toString#()Ljava/lang/String;" />
+      <node id="5841747851381535271" at="11,63,12,43" concept="8" />
+      <node id="6317379717814129922" at="15,49,16,21" concept="12" />
+      <node id="5841747851383361011" at="20,28,21,32" concept="8" />
+      <node id="5841747851381533067" at="11,0,14,0" concept="11" trace="symbol#(Ljava/lang/String;I)Ljetbrains/mps/logic/reactor/constraint/ConstraintSymbol;" />
+      <node id="5841747851381516224" at="15,0,18,0" concept="1" trace="ConstraintSymbol#(Ljava/lang/String;I)V" />
+      <node id="5841747851383347181" at="19,0,23,0" concept="6" trace="toString#()Ljava/lang/String;" />
       <scope id="5841747851381533071" at="11,63,12,43" />
       <scope id="5841747851381516231" at="15,49,16,21" />
       <scope id="5841747851383347185" at="20,28,21,32" />
@@ -57,33 +99,33 @@
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/6317379717814118653">
     <file name="Symbol.java">
-      <node id="6317379717814129293" at="8,42,9,17" concept="1" />
-      <node id="6317379717814157703" at="9,17,10,23" concept="1" />
-      <node id="5841747851381516257" at="13,22,14,14" concept="7" />
-      <node id="5841747851381516264" at="17,22,18,17" concept="7" />
-      <node id="5841747851381863229" at="22,25,23,20" concept="6" />
-      <node id="5841747851381863242" at="23,20,24,78" concept="1" />
-      <node id="5841747851381863258" at="24,78,25,38" concept="1" />
-      <node id="5841747851381863262" at="25,38,26,18" concept="7" />
-      <node id="5841747851381863158" at="31,20,32,18" concept="7" />
-      <node id="5841747851381863164" at="34,55,35,19" concept="7" />
-      <node id="5841747851381863177" at="36,5,37,0" concept="8" />
-      <node id="5841747851381863178" at="37,0,38,29" concept="6" />
-      <node id="5841747851381863196" at="39,67,40,19" concept="7" />
-      <node id="5841747851381863219" at="42,30,43,19" concept="7" />
-      <node id="5841747851381863221" at="44,5,45,0" concept="8" />
-      <node id="5841747851381863222" at="45,0,46,16" concept="7" />
-      <node id="5841747851381516267" at="49,0,50,0" concept="2" trace="id" />
-      <node id="5841747851381516270" at="50,0,51,0" concept="2" trace="arity" />
-      <node id="5841747851381516253" at="13,0,16,0" concept="5" trace="id#()Ljava/lang/String;" />
-      <node id="5841747851381516260" at="17,0,20,0" concept="5" trace="arity#()I" />
-      <node id="5841747851381863156" at="30,35,33,5" concept="4" />
-      <node id="5841747851381863162" at="33,5,36,5" concept="4" />
-      <node id="5841747851381863194" at="38,29,41,5" concept="4" />
-      <node id="5841747851381863214" at="41,5,44,5" concept="4" />
-      <node id="6317379717814128471" at="8,0,12,0" concept="0" trace="Symbol#(Ljava/lang/String;I)V" />
-      <node id="5841747851381863224" at="21,0,28,0" concept="5" trace="hashCode#()I" />
-      <node id="5841747851381863152" at="29,0,48,0" concept="5" trace="equals#(Ljava/lang/Object;)Z" />
+      <node id="6317379717814129293" at="8,42,9,17" concept="2" />
+      <node id="6317379717814157703" at="9,17,10,23" concept="2" />
+      <node id="5841747851381516257" at="13,22,14,14" concept="8" />
+      <node id="5841747851381516264" at="17,22,18,17" concept="8" />
+      <node id="5841747851381863229" at="22,25,23,20" concept="7" />
+      <node id="5841747851381863242" at="23,20,24,78" concept="2" />
+      <node id="5841747851381863258" at="24,78,25,38" concept="2" />
+      <node id="5841747851381863262" at="25,38,26,18" concept="8" />
+      <node id="5841747851381863158" at="31,20,32,18" concept="8" />
+      <node id="5841747851381863164" at="34,55,35,19" concept="8" />
+      <node id="5841747851381863177" at="36,5,37,0" concept="9" />
+      <node id="5841747851381863178" at="37,0,38,29" concept="7" />
+      <node id="5841747851381863196" at="39,67,40,19" concept="8" />
+      <node id="5841747851381863219" at="42,30,43,19" concept="8" />
+      <node id="5841747851381863221" at="44,5,45,0" concept="9" />
+      <node id="5841747851381863222" at="45,0,46,16" concept="8" />
+      <node id="5841747851381516267" at="49,0,50,0" concept="3" trace="id" />
+      <node id="5841747851381516270" at="50,0,51,0" concept="3" trace="arity" />
+      <node id="5841747851381516253" at="13,0,16,0" concept="6" trace="id#()Ljava/lang/String;" />
+      <node id="5841747851381516260" at="17,0,20,0" concept="6" trace="arity#()I" />
+      <node id="5841747851381863156" at="30,35,33,5" concept="5" />
+      <node id="5841747851381863162" at="33,5,36,5" concept="5" />
+      <node id="5841747851381863194" at="38,29,41,5" concept="5" />
+      <node id="5841747851381863214" at="41,5,44,5" concept="5" />
+      <node id="6317379717814128471" at="8,0,12,0" concept="1" trace="Symbol#(Ljava/lang/String;I)V" />
+      <node id="5841747851381863224" at="21,0,28,0" concept="6" trace="hashCode#()I" />
+      <node id="5841747851381863152" at="29,0,48,0" concept="6" trace="equals#(Ljava/lang/Object;)Z" />
       <scope id="5841747851381516256" at="13,22,14,14" />
       <scope id="5841747851381516263" at="17,22,18,17" />
       <scope id="5841747851381863157" at="31,20,32,18" />
@@ -112,10 +154,10 @@
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/6317379717814173903">
     <file name="PredicateSymbol.java">
-      <node id="6317379717823619735" at="8,48,9,21" concept="11" />
-      <node id="6317379717814175785" at="13,28,14,34" concept="7" />
-      <node id="6317379717814174713" at="8,0,11,0" concept="0" trace="PredicateSymbol#(Ljava/lang/String;I)V" />
-      <node id="6317379717814175781" at="12,0,16,0" concept="5" trace="toString#()Ljava/lang/String;" />
+      <node id="6317379717823619735" at="8,48,9,21" concept="12" />
+      <node id="6317379717814175785" at="13,28,14,34" concept="8" />
+      <node id="6317379717814174713" at="8,0,11,0" concept="1" trace="PredicateSymbol#(Ljava/lang/String;I)V" />
+      <node id="6317379717814175781" at="12,0,16,0" concept="6" trace="toString#()Ljava/lang/String;" />
       <scope id="6317379717814174717" at="8,48,9,21" />
       <scope id="6317379717814175784" at="13,28,14,34" />
       <scope id="6317379717814174713" at="8,0,11,0">
@@ -128,8 +170,8 @@
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/6317379717814244809">
     <file name="AndItem.java">
-      <node id="6317379717815747154" at="9,0,10,0" concept="5" trace="symbol#()Ljetbrains/mps/logic/reactor/constraint/Symbol;" />
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-      <scope id="6168558935193484643" at="54,53,55,46" />
-      <scope id="7785665572546325980" at="60,50,61,72" />
+      <scope id="7785665572546292862" at="48,82,49,39" />
+      <scope id="7785665572546284972" at="52,47,53,44" />
+      <scope id="6168558935193484643" at="57,53,58,37" />
+      <scope id="7785665572546325980" at="63,50,64,72" />
+      <scope id="2831834914717569548" at="17,90,19,27" />
+      <scope id="5217246026231897801" at="23,70,25,61" />
+      <scope id="5217246026231929912" at="29,50,31,38" />
       <scope id="2831834914716484929" at="13,0,16,0">
         <var name="predicateSymbols" id="2831834914717547255" />
       </scope>
-      <scope id="2831834914717569542" at="17,0,20,0">
-        <var name="computingTracer" id="2831834914717569543" />
-        <var name="predicateSymbols" id="2831834914717569545" />
-      </scope>
-      <scope id="7785665572546292859" at="45,0,48,0">
+      <scope id="7785665572546292859" at="48,0,51,0">
         <var name="constraint" id="7785665572546292863" />
         <var name="queryable" id="7785665572546292865" />
       </scope>
-      <scope id="7785665572546284968" at="49,0,52,0">
+      <scope id="7785665572546284968" at="52,0,55,0">
         <var name="symbol" id="7785665572546285221" />
       </scope>
-      <scope id="6168558935193484641" at="53,102,56,5">
+      <scope id="6168558935193484641" at="56,69,59,5">
         <var name="symbol" id="6168558935193484645" />
       </scope>
-      <scope id="95655808403395941" at="53,102,56,5" />
-      <scope id="5217246026231897797" at="21,0,25,0">
+      <scope id="95655808403395941" at="56,69,59,5" />
+      <scope id="2831834914717569542" at="17,0,21,0">
+        <var name="computingTracer" id="2831834914717569543" />
+        <var name="predicateSymbols" id="2831834914717569545" />
+      </scope>
+      <scope id="5217246026233172455" at="35,72,39,7">
+        <var name="queryable" id="6317379717822079129" />
+      </scope>
+      <scope id="7785665572546285625" at="62,61,66,40" />
+      <scope id="5217246026231897797" at="22,0,27,0">
         <var name="arg" id="5217246026231906313" />
         <var name="predicateSymbol" id="5217246026231904980" />
       </scope>
-      <scope id="5217246026231929908" at="26,0,30,0">
+      <scope id="5217246026231929908" at="28,0,33,0">
         <var name="arg" id="5217246026231935273" />
         <var name="symbol" id="5217246026231933720" />
       </scope>
-      <scope id="5217246026233172455" at="32,72,36,7">
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-      <scope id="95655808403395937" at="53,0,58,0">
-        <var name="computingTracer" id="2831834914717550245" />
+      <scope id="95655808403395937" at="56,0,61,0">
         <var name="predicateSymbols" id="2831834914717550247" />
       </scope>
-      <scope id="5217246026233172453" at="31,52,37,5">
+      <scope id="5217246026233172453" at="34,52,40,5">
         <var name="e" id="5217246026233172457" />
       </scope>
-      <scope id="7785665572546285620" at="59,0,65,0">
+      <scope id="7785665572546285620" at="62,0,68,0">
         <var name="predicateSymbol" id="7785665572546285621" />
       </scope>
-      <scope id="5217246026233157731" at="31,52,38,16" />
-      <scope id="5217246026233157724" at="31,0,40,0">
+      <scope id="5217246026233157731" at="34,52,41,16" />
+      <scope id="5217246026233157724" at="34,0,43,0">
         <var name="clazz" id="5217246026233157725" />
       </scope>
-      <unit id="7785665572546282176" at="11,0,68,0" name="jetbrains.mps.logic.reactor.constraint.SessionSolver" />
+      <unit id="7785665572546282176" at="11,0,72,0" name="jetbrains.mps.logic.reactor.constraint.SessionSolver" />
     </file>
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/7785665572546285342">
     <file name="AbstractPredicate.java">
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+      <node id="6317379717821161546" at="11,49,12,31" concept="2" />
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+      <node id="7785665572546293515" at="35,20,36,18" concept="8" />
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+      <node id="7785665572546293553" at="43,100,44,19" concept="8" />
+      <node id="7785665572546293569" at="45,5,46,0" concept="9" />
+      <node id="7785665572546293570" at="46,0,47,16" concept="8" />
+      <node id="7785665572546293577" at="51,25,52,20" concept="7" />
+      <node id="7785665572546293590" at="52,20,53,91" concept="2" />
+      <node id="7785665572546293602" at="53,91,54,18" concept="8" />
+      <node id="6317379717821161541" at="57,0,58,0" concept="3" trace="arguments" />
+      <node id="7785665572546286535" at="11,0,14,0" concept="1" trace="AbstractPredicate#(null)V" />
+      <node id="7785665572546678499" at="20,0,23,0" concept="6" trace="asConstraint#()Ljetbrains/mps/logic/reactor/constraint/Constraint;" />
+      <node id="7785665572546684164" at="24,0,27,0" concept="6" trace="asAutoConstraint#()Ljetbrains/mps/logic/reactor/constraint/Predicate;" />
+      <node id="7785665572546293513" at="34,35,37,5" concept="5" />
+      <node id="7785665572546293519" at="37,5,40,5" concept="5" />
+      <node id="7785665572546293551" at="42,51,45,5" concept="5" />
+      <node id="6317379717821176300" at="15,0,19,0" concept="6" trace="arguments#()Ljava/util/Collection;" />
+      <node id="7785665572546318121" at="28,0,32,0" concept="6" trace="toString#()Ljava/lang/String;" />
+      <node id="7785665572546293572" at="50,0,56,0" concept="6" trace="hashCode#()I" />
+      <node id="7785665572546293509" at="33,0,49,0" concept="6" trace="equals#(Ljava/lang/Object;)Z" />
       <scope id="7785665572546286539" at="11,49,12,31" />
-      <scope id="6317379717821176305" at="16,35,17,66" />
+      <scope id="6317379717821176305" at="16,36,17,66" />
       <scope id="7785665572546678503" at="20,36,21,29" />
       <scope id="7785665572546684167" at="24,39,25,28" />
       <scope id="7785665572546318125" at="29,28,30,31" />
@@ -392,8 +442,8 @@
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/7785665572546345623">
     <file name="Constraint.java">
-      <node id="6317379717814333032" at="14,0,15,0" concept="5" trace="symbol#()Ljetbrains/mps/logic/reactor/constraint/ConstraintSymbol;" />
-      <node id="8225968737376931639" at="16,0,17,0" concept="5" trace="argumentTypes#()Ljava/util/List;" />
+      <node id="6317379717814333032" at="14,0,15,0" concept="6" trace="symbol#()Ljetbrains/mps/logic/reactor/constraint/ConstraintSymbol;" />
+      <node id="8225968737376931639" at="16,0,17,0" concept="6" trace="argumentTypes#()Ljava/util/List;" />
       <scope id="6317379717814333032" at="14,0,15,0" />
       <scope id="8225968737376931639" at="16,0,17,0" />
       <unit id="7785665572546345623" at="12,0,19,0" name="jetbrains.mps.logic.reactor.constraint.Constraint" />
@@ -401,7 +451,7 @@
   </root>
   <root nodeRef="r:2a79c8aa-e372-4c00-8d71-5d7f3db517e4(jetbrains.mps.logic.reactor.constraint)/7785665572546359770">
     <file name="Predicate.java">
-      <node id="7785665572546360338" at="11,0,12,0" concept="5" trace="symbol#()Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;" />
+      <node id="7785665572546360338" at="11,0,12,0" concept="6" trace="symbol#()Ljetbrains/mps/logic/reactor/constraint/PredicateSymbol;" />
       <scope id="7785665572546360338" at="11,0,12,0" />
       <unit id="7785665572546359770" at="9,0,14,0" name="jetbrains.mps.logic.reactor.constraint.Predicate" />
     </file>
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogicalVar.java b/reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogicalVar.java
deleted file mode 100644
index 907e48d4..00000000
--- a/reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogicalVar.java
+++ /dev/null
@@ -1,10 +0,0 @@
-package jetbrains.mps.logic.reactor.logical;
-
-/*Generated by MPS */
-
-
-public interface ILogicalVar {
-
-  public ILogical<?> logical();
-
-}
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogical.java b/reactor/API/src/jetbrains/mps/logic/reactor/logical/Logical.java
similarity index 70%
rename from reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogical.java
rename to reactor/API/src/jetbrains/mps/logic/reactor/logical/Logical.java
index 72bc7e5c..69aa78d1 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/logical/ILogical.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/logical/Logical.java
@@ -3,13 +3,13 @@ package jetbrains.mps.logic.reactor.logical;
 /*Generated by MPS */
 
 
-public interface ILogical<T> {
+public interface Logical<T> {
 
   public String name();
 
   public String name(NamingContext namingContext);
 
-  public ILogical<T> findRoot();
+  public Logical<T> findRoot();
 
   public T value();
 
@@ -17,4 +17,6 @@ public interface ILogical<T> {
 
   public boolean isWildcard();
 
+  public LogicalPattern pattern();
+
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/LogicalPattern.java b/reactor/API/src/jetbrains/mps/logic/reactor/logical/LogicalPattern.java
new file mode 100644
index 00000000..5f30cffb
--- /dev/null
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/logical/LogicalPattern.java
@@ -0,0 +1,16 @@
+package jetbrains.mps.logic.reactor.logical;
+
+/*Generated by MPS */
+
+
+public interface LogicalPattern {
+
+  public String name();
+
+  public String name(NamingContext namingContext);
+
+  public boolean isWildcard();
+
+  public Class<?> type();
+
+}
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/MultiLogicalPattern.java b/reactor/API/src/jetbrains/mps/logic/reactor/logical/MultiLogicalPattern.java
new file mode 100644
index 00000000..f9ff2150
--- /dev/null
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/logical/MultiLogicalPattern.java
@@ -0,0 +1,14 @@
+package jetbrains.mps.logic.reactor.logical;
+
+/*Generated by MPS */
+
+
+public interface MultiLogicalPattern extends LogicalPattern {
+
+  public int cardinality();
+
+  public LogicalPattern patternAt(int idx);
+
+  public LogicalPattern[] toArray();
+
+}
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/NamingContext.java b/reactor/API/src/jetbrains/mps/logic/reactor/logical/NamingContext.java
index 906831b9..7460e364 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/logical/NamingContext.java
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/logical/NamingContext.java
@@ -8,11 +8,19 @@ import java.util.IdentityHashMap;
 
 public class NamingContext {
 
-  public String uniqueName(ILogical logical) {
-    if (!(cachedUnique.containsKey(logical))) {
-      cachedUnique.put(logical, makeUnique(logical.name()));
+  public String uniqueName(Logical logical) {
+    return cachedOrMakeUnique(logical, logical.name());
+  }
+
+  public String uniqueName(LogicalPattern logical) {
+    return cachedOrMakeUnique(logical, logical.name());
+  }
+
+  private String cachedOrMakeUnique(Object named, String name) {
+    if (!(cachedUnique.containsKey(named))) {
+      cachedUnique.put(named, makeUnique(name));
     }
-    return cachedUnique.get(logical);
+    return cachedUnique.get(named);
   }
 
   private String makeUnique(String name) {
@@ -28,6 +36,6 @@ public class NamingContext {
 
   private Map<String, Integer> uniqueCounters = new HashMap<String, Integer>();
 
-  private Map<ILogical, String> cachedUnique = new IdentityHashMap<ILogical, String>();
+  private Map<Object, String> cachedUnique = new IdentityHashMap<Object, String>();
 
 }
diff --git a/reactor/API/src/jetbrains/mps/logic/reactor/logical/trace.info b/reactor/API/src/jetbrains/mps/logic/reactor/logical/trace.info
index e4b5c5a6..9eaab8bd 100644
--- a/reactor/API/src/jetbrains/mps/logic/reactor/logical/trace.info
+++ b/reactor/API/src/jetbrains/mps/logic/reactor/logical/trace.info
@@ -7,13 +7,14 @@
   <concept fqn="jetbrains.mps.baseLanguage.structure.LocalVariableDeclarationStatement" />
   <concept fqn="jetbrains.mps.baseLanguage.structure.ReturnStatement" />
   <root nodeRef="r:7365f7fe-12e6-4229-8901-f6dc6d5df03f(jetbrains.mps.logic.reactor.logical)/1564179198503508264">
-    <file name="ILogical.java">
+    <file name="Logical.java">
       <node id="7045828502339522708" at="8,0,9,0" concept="3" trace="name#()Ljava/lang/String;" />
       <node id="2966490507992539037" at="10,0,11,0" concept="3" trace="name#(Ljetbrains/mps/logic/reactor/logical/NamingContext;)Ljava/lang/String;" />
-      <node id="238586457663160034" at="12,0,13,0" concept="3" trace="findRoot#()Ljetbrains/mps/logic/reactor/logical/ILogical;" />
+      <node id="238586457663160034" at="12,0,13,0" concept="3" trace="findRoot#()Ljetbrains/mps/logic/reactor/logical/Logical;" />
       <node id="1564179198503509166" at="14,0,15,0" concept="3" trace="value#()null" />
       <node id="1564179198503509045" at="16,0,17,0" concept="3" trace="isBound#()Z" />
       <node id="3058061960962299083" at="18,0,19,0" concept="3" trace="isWildcard#()Z" />
+      <node id="8897567155601592702" at="20,0,21,0" concept="3" trace="pattern#()Ljetbrains/mps/logic/reactor/logical/LogicalPattern;" />
       <scope id="7045828502339522708" at="8,0,9,0" />
       <scope id="2966490507992539037" at="10,0,11,0">
         <var name="namingContext" id="2966490507992541231" />
@@ -22,49 +23,84 @@
       <scope id="1564179198503509166" at="14,0,15,0" />
       <scope id="1564179198503509045" at="16,0,17,0" />
       <scope id="3058061960962299083" at="18,0,19,0" />
-      <unit id="1564179198503508264" at="6,0,21,0" name="jetbrains.mps.logic.reactor.logical.ILogical" />
+      <scope id="8897567155601592702" at="20,0,21,0" />
+      <unit id="1564179198503508264" at="6,0,23,0" name="jetbrains.mps.logic.reactor.logical.Logical" />
     </file>
   </root>
   <root nodeRef="r:7365f7fe-12e6-4229-8901-f6dc6d5df03f(jetbrains.mps.logic.reactor.logical)/2966490507992442162">
     <file name="NamingContext.java">
-      <node id="2966490507992493081" at="12,47,13,60" concept="0" />
-      <node id="2966490507992496215" at="14,5,15,37" concept="5" />
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-      <node id="2966490507992442764" at="29,0,30,0" concept="1" trace="uniqueCounters" />
-      <node id="2966490507992487240" at="31,0,32,0" concept="1" trace="cachedUnique" />
-      <node id="2966490507992491063" at="11,46,14,5" concept="2" />
-      <node id="2966490507992478411" at="18,0,22,0" concept="3" trace="makeUnique#(Ljava/lang/String;)Ljava/lang/String;" />
-      <node id="7788002923752647499" at="23,0,28,0" concept="3" trace="getAndIncrementCounter#(Ljava/lang/String;)I" />
-      <node id="2966490507992442243" at="11,0,17,0" concept="3" trace="uniqueName#(Ljetbrains/mps/logic/reactor/logical/ILogical;)Ljava/lang/String;" />
-      <scope id="2966490507992491064" at="12,47,13,60" />
-      <scope id="2966490507992478415" at="18,42,20,38">
+      <node id="8897567155601872170" at="11,45,12,55" concept="5" />
+      <node id="8897567155601877662" at="15,52,16,55" concept="5" />
+      <node id="8897567155601872137" at="20,45,21,48" concept="0" />
+      <node id="8897567155601872149" at="22,5,23,35" concept="5" />
+      <node id="7788002923752702358" at="26,42,27,41" concept="4" />
+      <node id="7788002923752701639" at="27,41,28,38" concept="5" />
+      <node id="7788002923752672045" at="31,51,32,82" concept="4" />
+      <node id="7788002923752674066" at="32,82,33,36" concept="0" />
+      <node id="7788002923752668035" at="33,36,34,13" concept="5" />
+      <node id="2966490507992442764" at="37,0,38,0" concept="1" trace="uniqueCounters" />
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