add realistic solver

7 files changed, 3322 insertions, 0 deletions

diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/.gitignore b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/.gitignore
new file mode 100644
index 00000000..c42ca056
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/.gitignore
@@ -0,0 +1,8 @@
+/.Ecore_pattern.java._trace
+/.MoreThenFiveSuperTypes.java._trace
+/.DirectSupertype.java._trace
+/.Ecore.java._trace
+/.LoopInInheritence.java._trace
+/.NonSymmetricOpposite.java._trace
+/.Opposite.java._trace
+/.OppositeDifferentClass.java._trace
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/DirectSupertype.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/DirectSupertype.java
new file mode 100644
index 00000000..a6ffad45
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/DirectSupertype.java
@@ -0,0 +1,692 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.log4j.Logger;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.viatra.query.runtime.api.IPatternMatch;
+import org.eclipse.viatra.query.runtime.api.IQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFPQuery;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.impl.BaseMatcher;
+import org.eclipse.viatra.query.runtime.api.impl.BasePatternMatch;
+import org.eclipse.viatra.query.runtime.emf.types.EClassTransitiveInstancesKey;
+import org.eclipse.viatra.query.runtime.emf.types.EStructuralFeatureInstancesKey;
+import org.eclipse.viatra.query.runtime.matchers.backend.QueryEvaluationHint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PBody;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PVariable;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.Equality;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.ExportedParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.TypeConstraint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameterDirection;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PVisibility;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuples;
+import org.eclipse.viatra.query.runtime.util.ViatraQueryLoggingUtil;
+
+/**
+ * A pattern-specific query specification that can instantiate Matcher in a type-safe way.
+ * 
+ * <p>Original source:
+ *         <code><pre>
+ *         pattern directSupertype(a: EClass, b:EClass) {
+ *              EClass.eSuperTypes(a,b);
+ *         }
+ * </pre></code>
+ * 
+ * @see Matcher
+ * @see Match
+ * 
+ */
+@SuppressWarnings("all")
+public final class DirectSupertype extends BaseGeneratedEMFQuerySpecification<DirectSupertype.Matcher> {
+  /**
+   * Pattern-specific match representation of the ecore.directSupertype pattern,
+   * to be used in conjunction with {@link Matcher}.
+   * 
+   * <p>Class fields correspond to parameters of the pattern. Fields with value null are considered unassigned.
+   * Each instance is a (possibly partial) substitution of pattern parameters,
+   * usable to represent a match of the pattern in the result of a query,
+   * or to specify the bound (fixed) input parameters when issuing a query.
+   * 
+   * @see Matcher
+   * 
+   */
+  public static abstract class Match extends BasePatternMatch {
+    private EClass fA;
+    
+    private EClass fB;
+    
+    private static List<String> parameterNames = makeImmutableList("a", "b");
+    
+    private Match(final EClass pA, final EClass pB) {
+      this.fA = pA;
+      this.fB = pB;
+    }
+    
+    @Override
+    public Object get(final String parameterName) {
+      if ("a".equals(parameterName)) return this.fA;
+      if ("b".equals(parameterName)) return this.fB;
+      return null;
+    }
+    
+    public EClass getA() {
+      return this.fA;
+    }
+    
+    public EClass getB() {
+      return this.fB;
+    }
+    
+    @Override
+    public boolean set(final String parameterName, final Object newValue) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      if ("a".equals(parameterName) ) {
+          this.fA = (EClass) newValue;
+          return true;
+      }
+      if ("b".equals(parameterName) ) {
+          this.fB = (EClass) newValue;
+          return true;
+      }
+      return false;
+    }
+    
+    public void setA(final EClass pA) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fA = pA;
+    }
+    
+    public void setB(final EClass pB) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fB = pB;
+    }
+    
+    @Override
+    public String patternName() {
+      return "ecore.directSupertype";
+    }
+    
+    @Override
+    public List<String> parameterNames() {
+      return DirectSupertype.Match.parameterNames;
+    }
+    
+    @Override
+    public Object[] toArray() {
+      return new Object[]{fA, fB};
+    }
+    
+    @Override
+    public DirectSupertype.Match toImmutable() {
+      return isMutable() ? newMatch(fA, fB) : this;
+    }
+    
+    @Override
+    public String prettyPrint() {
+      StringBuilder result = new StringBuilder();
+      result.append("\"a\"=" + prettyPrintValue(fA) + ", ");
+      result.append("\"b\"=" + prettyPrintValue(fB));
+      return result.toString();
+    }
+    
+    @Override
+    public int hashCode() {
+      return Objects.hash(fA, fB);
+    }
+    
+    @Override
+    public boolean equals(final Object obj) {
+      if (this == obj)
+          return true;
+      if (obj == null) {
+          return false;
+      }
+      if ((obj instanceof DirectSupertype.Match)) {
+          DirectSupertype.Match other = (DirectSupertype.Match) obj;
+          return Objects.equals(fA, other.fA) && Objects.equals(fB, other.fB);
+      } else {
+          // this should be infrequent
+          if (!(obj instanceof IPatternMatch)) {
+              return false;
+          }
+          IPatternMatch otherSig  = (IPatternMatch) obj;
+          return Objects.equals(specification(), otherSig.specification()) && Arrays.deepEquals(toArray(), otherSig.toArray());
+      }
+    }
+    
+    @Override
+    public DirectSupertype specification() {
+      return DirectSupertype.instance();
+    }
+    
+    /**
+     * Returns an empty, mutable match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @return the empty match.
+     * 
+     */
+    public static DirectSupertype.Match newEmptyMatch() {
+      return new Mutable(null, null);
+    }
+    
+    /**
+     * Returns a mutable (partial) match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the new, mutable (partial) match object.
+     * 
+     */
+    public static DirectSupertype.Match newMutableMatch(final EClass pA, final EClass pB) {
+      return new Mutable(pA, pB);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public static DirectSupertype.Match newMatch(final EClass pA, final EClass pB) {
+      return new Immutable(pA, pB);
+    }
+    
+    private static final class Mutable extends DirectSupertype.Match {
+      Mutable(final EClass pA, final EClass pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return true;
+      }
+    }
+    
+    private static final class Immutable extends DirectSupertype.Match {
+      Immutable(final EClass pA, final EClass pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return false;
+      }
+    }
+  }
+  
+  /**
+   * Generated pattern matcher API of the ecore.directSupertype pattern,
+   * providing pattern-specific query methods.
+   * 
+   * <p>Use the pattern matcher on a given model via {@link #on(ViatraQueryEngine)},
+   * e.g. in conjunction with {@link ViatraQueryEngine#on(QueryScope)}.
+   * 
+   * <p>Matches of the pattern will be represented as {@link Match}.
+   * 
+   * <p>Original source:
+   * <code><pre>
+   * pattern directSupertype(a: EClass, b:EClass) {
+   *    EClass.eSuperTypes(a,b);
+   * }
+   * </pre></code>
+   * 
+   * @see Match
+   * @see DirectSupertype
+   * 
+   */
+  public static class Matcher extends BaseMatcher<DirectSupertype.Match> {
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    public static DirectSupertype.Matcher on(final ViatraQueryEngine engine) {
+      // check if matcher already exists
+      Matcher matcher = engine.getExistingMatcher(querySpecification());
+      if (matcher == null) {
+          matcher = (Matcher)engine.getMatcher(querySpecification());
+      }
+      return matcher;
+    }
+    
+    /**
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * @return an initialized matcher
+     * @noreference This method is for internal matcher initialization by the framework, do not call it manually.
+     * 
+     */
+    public static DirectSupertype.Matcher create() {
+      return new Matcher();
+    }
+    
+    private static final int POSITION_A = 0;
+    
+    private static final int POSITION_B = 1;
+    
+    private static final Logger LOGGER = ViatraQueryLoggingUtil.getLogger(DirectSupertype.Matcher.class);
+    
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    private Matcher() {
+      super(querySpecification());
+    }
+    
+    /**
+     * Returns the set of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return matches represented as a Match object.
+     * 
+     */
+    public Collection<DirectSupertype.Match> getAllMatches(final EClass pA, final EClass pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Returns a stream of all matches of the pattern that conform to the given fixed values of some parameters.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a stream of matches represented as a Match object.
+     * 
+     */
+    public Stream<DirectSupertype.Match> streamAllMatches(final EClass pA, final EClass pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a match represented as a Match object, or null if no match is found.
+     * 
+     */
+    public Optional<DirectSupertype.Match> getOneArbitraryMatch(final EClass pA, final EClass pB) {
+      return rawGetOneArbitraryMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Indicates whether the given combination of specified pattern parameters constitute a valid pattern match,
+     * under any possible substitution of the unspecified parameters (if any).
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return true if the input is a valid (partial) match of the pattern.
+     * 
+     */
+    public boolean hasMatch(final EClass pA, final EClass pB) {
+      return rawHasMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns the number of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the number of pattern matches found.
+     * 
+     */
+    public int countMatches(final EClass pA, final EClass pB) {
+      return rawCountMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Executes the given processor on an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @param processor the action that will process the selected match.
+     * @return true if the pattern has at least one match with the given parameter values, false if the processor was not invoked
+     * 
+     */
+    public boolean forOneArbitraryMatch(final EClass pA, final EClass pB, final Consumer<? super DirectSupertype.Match> processor) {
+      return rawForOneArbitraryMatch(new Object[]{pA, pB}, processor);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public DirectSupertype.Match newMatch(final EClass pA, final EClass pB) {
+      return DirectSupertype.Match.newMatch(pA, pB);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EClass> rawStreamAllValuesOfa(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_A, parameters).map(EClass.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfa(final DirectSupertype.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfa(final EClass pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfa(final DirectSupertype.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfa(final EClass pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EClass> rawStreamAllValuesOfb(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_B, parameters).map(EClass.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfb(final DirectSupertype.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfb(final EClass pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfb(final DirectSupertype.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfb(final EClass pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null}).collect(Collectors.toSet());
+    }
+    
+    @Override
+    protected DirectSupertype.Match tupleToMatch(final Tuple t) {
+      try {
+          return DirectSupertype.Match.newMatch((EClass) t.get(POSITION_A), (EClass) t.get(POSITION_B));
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in tuple not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected DirectSupertype.Match arrayToMatch(final Object[] match) {
+      try {
+          return DirectSupertype.Match.newMatch((EClass) match[POSITION_A], (EClass) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected DirectSupertype.Match arrayToMatchMutable(final Object[] match) {
+      try {
+          return DirectSupertype.Match.newMutableMatch((EClass) match[POSITION_A], (EClass) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    /**
+     * @return the singleton instance of the query specification of this pattern
+     * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+     * 
+     */
+    public static IQuerySpecification<DirectSupertype.Matcher> querySpecification() {
+      return DirectSupertype.instance();
+    }
+  }
+  
+  private DirectSupertype() {
+    super(GeneratedPQuery.INSTANCE);
+  }
+  
+  /**
+   * @return the singleton instance of the query specification
+   * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+   * 
+   */
+  public static DirectSupertype instance() {
+    try{
+        return LazyHolder.INSTANCE;
+    } catch (ExceptionInInitializerError err) {
+        throw processInitializerError(err);
+    }
+  }
+  
+  @Override
+  protected DirectSupertype.Matcher instantiate(final ViatraQueryEngine engine) {
+    return DirectSupertype.Matcher.on(engine);
+  }
+  
+  @Override
+  public DirectSupertype.Matcher instantiate() {
+    return DirectSupertype.Matcher.create();
+  }
+  
+  @Override
+  public DirectSupertype.Match newEmptyMatch() {
+    return DirectSupertype.Match.newEmptyMatch();
+  }
+  
+  @Override
+  public DirectSupertype.Match newMatch(final Object... parameters) {
+    return DirectSupertype.Match.newMatch((org.eclipse.emf.ecore.EClass) parameters[0], (org.eclipse.emf.ecore.EClass) parameters[1]);
+  }
+  
+  /**
+   * Inner class allowing the singleton instance of {@link JvmGenericType: ecore.DirectSupertype (visibility: PUBLIC, simpleName: DirectSupertype, identifier: ecore.DirectSupertype, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)} to be created 
+   *     <b>not</b> at the class load time of the outer class, 
+   *     but rather at the first call to {@link JvmGenericType: ecore.DirectSupertype (visibility: PUBLIC, simpleName: DirectSupertype, identifier: ecore.DirectSupertype, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)#instance()}.
+   * 
+   * <p> This workaround is required e.g. to support recursion.
+   * 
+   */
+  private static class LazyHolder {
+    private static final DirectSupertype INSTANCE = new DirectSupertype();
+    
+    /**
+     * Statically initializes the query specification <b>after</b> the field {@link #INSTANCE} is assigned.
+     * This initialization order is required to support indirect recursion.
+     * 
+     * <p> The static initializer is defined using a helper field to work around limitations of the code generator.
+     * 
+     */
+    private static final Object STATIC_INITIALIZER = ensureInitialized();
+    
+    public static Object ensureInitialized() {
+      INSTANCE.ensureInitializedInternal();
+      return null;
+    }
+  }
+  
+  private static class GeneratedPQuery extends BaseGeneratedEMFPQuery {
+    private static final DirectSupertype.GeneratedPQuery INSTANCE = new GeneratedPQuery();
+    
+    private final PParameter parameter_a = new PParameter("a", "org.eclipse.emf.ecore.EClass", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EClass")), PParameterDirection.INOUT);
+    
+    private final PParameter parameter_b = new PParameter("b", "org.eclipse.emf.ecore.EClass", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EClass")), PParameterDirection.INOUT);
+    
+    private final List<PParameter> parameters = Arrays.asList(parameter_a, parameter_b);
+    
+    private GeneratedPQuery() {
+      super(PVisibility.PUBLIC);
+    }
+    
+    @Override
+    public String getFullyQualifiedName() {
+      return "ecore.directSupertype";
+    }
+    
+    @Override
+    public List<String> getParameterNames() {
+      return Arrays.asList("a","b");
+    }
+    
+    @Override
+    public List<PParameter> getParameters() {
+      return parameters;
+    }
+    
+    @Override
+    public Set<PBody> doGetContainedBodies() {
+      setEvaluationHints(new QueryEvaluationHint(null, QueryEvaluationHint.BackendRequirement.UNSPECIFIED));
+      Set<PBody> bodies = new LinkedHashSet<>();
+      {
+          PBody body = new PBody(this);
+          PVariable var_a = body.getOrCreateVariableByName("a");
+          PVariable var_b = body.getOrCreateVariableByName("b");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var_b), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          body.setSymbolicParameters(Arrays.<ExportedParameter>asList(
+             new ExportedParameter(body, var_a, parameter_a),
+             new ExportedParameter(body, var_b, parameter_b)
+          ));
+          //    EClass.eSuperTypes(a,b)
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          PVariable var__virtual_0_ = body.getOrCreateVariableByName(".virtual{0}");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a, var__virtual_0_), new EStructuralFeatureInstancesKey(getFeatureLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass", "eSuperTypes")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var__virtual_0_), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          new Equality(body, var__virtual_0_, var_b);
+          bodies.add(body);
+      }
+      return bodies;
+    }
+  }
+}
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Ecore.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Ecore.java
new file mode 100644
index 00000000..bca43a17
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Ecore.java
@@ -0,0 +1,97 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import ecore.DirectSupertype;
+import ecore.LoopInInheritence;
+import ecore.NonSymmetricOpposite;
+import ecore.Opposite;
+import ecore.OppositeDifferentClass;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedPatternGroup;
+
+/**
+ * A pattern group formed of all public patterns defined in Ecore.vql.
+ * 
+ * <p>Use the static instance as any {@link interface org.eclipse.viatra.query.runtime.api.IQueryGroup}, to conveniently prepare
+ * a VIATRA Query engine for matching all patterns originally defined in file Ecore.vql,
+ * in order to achieve better performance than one-by-one on-demand matcher initialization.
+ * 
+ * <p> From package ecore, the group contains the definition of the following patterns: <ul>
+ * <li>directSupertype</li>
+ * <li>loopInInheritence</li>
+ * <li>opposite</li>
+ * <li>oppositeDifferentClass</li>
+ * <li>nonSymmetricOpposite</li>
+ * </ul>
+ * 
+ * @see IQueryGroup
+ * 
+ */
+@SuppressWarnings("all")
+public final class Ecore extends BaseGeneratedPatternGroup {
+  /**
+   * Access the pattern group.
+   * 
+   * @return the singleton instance of the group
+   * @throws ViatraQueryRuntimeException if there was an error loading the generated code of pattern specifications
+   * 
+   */
+  public static Ecore instance() {
+    if (INSTANCE == null) {
+        INSTANCE = new Ecore();
+    }
+    return INSTANCE;
+  }
+  
+  private static Ecore INSTANCE;
+  
+  private Ecore() {
+    querySpecifications.add(DirectSupertype.instance());
+    querySpecifications.add(LoopInInheritence.instance());
+    querySpecifications.add(Opposite.instance());
+    querySpecifications.add(OppositeDifferentClass.instance());
+    querySpecifications.add(NonSymmetricOpposite.instance());
+  }
+  
+  public DirectSupertype getDirectSupertype() {
+    return DirectSupertype.instance();
+  }
+  
+  public DirectSupertype.Matcher getDirectSupertype(final ViatraQueryEngine engine) {
+    return DirectSupertype.Matcher.on(engine);
+  }
+  
+  public LoopInInheritence getLoopInInheritence() {
+    return LoopInInheritence.instance();
+  }
+  
+  public LoopInInheritence.Matcher getLoopInInheritence(final ViatraQueryEngine engine) {
+    return LoopInInheritence.Matcher.on(engine);
+  }
+  
+  public Opposite getOpposite() {
+    return Opposite.instance();
+  }
+  
+  public Opposite.Matcher getOpposite(final ViatraQueryEngine engine) {
+    return Opposite.Matcher.on(engine);
+  }
+  
+  public OppositeDifferentClass getOppositeDifferentClass() {
+    return OppositeDifferentClass.instance();
+  }
+  
+  public OppositeDifferentClass.Matcher getOppositeDifferentClass(final ViatraQueryEngine engine) {
+    return OppositeDifferentClass.Matcher.on(engine);
+  }
+  
+  public NonSymmetricOpposite getNonSymmetricOpposite() {
+    return NonSymmetricOpposite.instance();
+  }
+  
+  public NonSymmetricOpposite.Matcher getNonSymmetricOpposite(final ViatraQueryEngine engine) {
+    return NonSymmetricOpposite.Matcher.on(engine);
+  }
+}
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/LoopInInheritence.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/LoopInInheritence.java
new file mode 100644
index 00000000..fb14941f
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/LoopInInheritence.java
@@ -0,0 +1,548 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import ecore.DirectSupertype;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.log4j.Logger;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.viatra.query.runtime.api.IPatternMatch;
+import org.eclipse.viatra.query.runtime.api.IQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFPQuery;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.impl.BaseMatcher;
+import org.eclipse.viatra.query.runtime.api.impl.BasePatternMatch;
+import org.eclipse.viatra.query.runtime.emf.types.EClassTransitiveInstancesKey;
+import org.eclipse.viatra.query.runtime.matchers.backend.QueryEvaluationHint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PBody;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PVariable;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.PAnnotation;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.ParameterReference;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.ExportedParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.BinaryTransitiveClosure;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.TypeConstraint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameterDirection;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PVisibility;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuples;
+import org.eclipse.viatra.query.runtime.util.ViatraQueryLoggingUtil;
+
+/**
+ * A pattern-specific query specification that can instantiate Matcher in a type-safe way.
+ * 
+ * <p>Original source:
+ *         <code><pre>
+ *         {@literal @}Constraint(key={a}, severity="error", message="error")
+ *         pattern loopInInheritence(a: EClass) {
+ *              find directSupertype+(a,a);
+ *         }
+ * </pre></code>
+ * 
+ * @see Matcher
+ * @see Match
+ * 
+ */
+@SuppressWarnings("all")
+public final class LoopInInheritence extends BaseGeneratedEMFQuerySpecification<LoopInInheritence.Matcher> {
+  /**
+   * Pattern-specific match representation of the ecore.loopInInheritence pattern,
+   * to be used in conjunction with {@link Matcher}.
+   * 
+   * <p>Class fields correspond to parameters of the pattern. Fields with value null are considered unassigned.
+   * Each instance is a (possibly partial) substitution of pattern parameters,
+   * usable to represent a match of the pattern in the result of a query,
+   * or to specify the bound (fixed) input parameters when issuing a query.
+   * 
+   * @see Matcher
+   * 
+   */
+  public static abstract class Match extends BasePatternMatch {
+    private EClass fA;
+    
+    private static List<String> parameterNames = makeImmutableList("a");
+    
+    private Match(final EClass pA) {
+      this.fA = pA;
+    }
+    
+    @Override
+    public Object get(final String parameterName) {
+      if ("a".equals(parameterName)) return this.fA;
+      return null;
+    }
+    
+    public EClass getA() {
+      return this.fA;
+    }
+    
+    @Override
+    public boolean set(final String parameterName, final Object newValue) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      if ("a".equals(parameterName) ) {
+          this.fA = (EClass) newValue;
+          return true;
+      }
+      return false;
+    }
+    
+    public void setA(final EClass pA) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fA = pA;
+    }
+    
+    @Override
+    public String patternName() {
+      return "ecore.loopInInheritence";
+    }
+    
+    @Override
+    public List<String> parameterNames() {
+      return LoopInInheritence.Match.parameterNames;
+    }
+    
+    @Override
+    public Object[] toArray() {
+      return new Object[]{fA};
+    }
+    
+    @Override
+    public LoopInInheritence.Match toImmutable() {
+      return isMutable() ? newMatch(fA) : this;
+    }
+    
+    @Override
+    public String prettyPrint() {
+      StringBuilder result = new StringBuilder();
+      result.append("\"a\"=" + prettyPrintValue(fA));
+      return result.toString();
+    }
+    
+    @Override
+    public int hashCode() {
+      return Objects.hash(fA);
+    }
+    
+    @Override
+    public boolean equals(final Object obj) {
+      if (this == obj)
+          return true;
+      if (obj == null) {
+          return false;
+      }
+      if ((obj instanceof LoopInInheritence.Match)) {
+          LoopInInheritence.Match other = (LoopInInheritence.Match) obj;
+          return Objects.equals(fA, other.fA);
+      } else {
+          // this should be infrequent
+          if (!(obj instanceof IPatternMatch)) {
+              return false;
+          }
+          IPatternMatch otherSig  = (IPatternMatch) obj;
+          return Objects.equals(specification(), otherSig.specification()) && Arrays.deepEquals(toArray(), otherSig.toArray());
+      }
+    }
+    
+    @Override
+    public LoopInInheritence specification() {
+      return LoopInInheritence.instance();
+    }
+    
+    /**
+     * Returns an empty, mutable match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @return the empty match.
+     * 
+     */
+    public static LoopInInheritence.Match newEmptyMatch() {
+      return new Mutable(null);
+    }
+    
+    /**
+     * Returns a mutable (partial) match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the new, mutable (partial) match object.
+     * 
+     */
+    public static LoopInInheritence.Match newMutableMatch(final EClass pA) {
+      return new Mutable(pA);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public static LoopInInheritence.Match newMatch(final EClass pA) {
+      return new Immutable(pA);
+    }
+    
+    private static final class Mutable extends LoopInInheritence.Match {
+      Mutable(final EClass pA) {
+        super(pA);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return true;
+      }
+    }
+    
+    private static final class Immutable extends LoopInInheritence.Match {
+      Immutable(final EClass pA) {
+        super(pA);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return false;
+      }
+    }
+  }
+  
+  /**
+   * Generated pattern matcher API of the ecore.loopInInheritence pattern,
+   * providing pattern-specific query methods.
+   * 
+   * <p>Use the pattern matcher on a given model via {@link #on(ViatraQueryEngine)},
+   * e.g. in conjunction with {@link ViatraQueryEngine#on(QueryScope)}.
+   * 
+   * <p>Matches of the pattern will be represented as {@link Match}.
+   * 
+   * <p>Original source:
+   * <code><pre>
+   * {@literal @}Constraint(key={a}, severity="error", message="error")
+   * pattern loopInInheritence(a: EClass) {
+   *    find directSupertype+(a,a);
+   * }
+   * </pre></code>
+   * 
+   * @see Match
+   * @see LoopInInheritence
+   * 
+   */
+  public static class Matcher extends BaseMatcher<LoopInInheritence.Match> {
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    public static LoopInInheritence.Matcher on(final ViatraQueryEngine engine) {
+      // check if matcher already exists
+      Matcher matcher = engine.getExistingMatcher(querySpecification());
+      if (matcher == null) {
+          matcher = (Matcher)engine.getMatcher(querySpecification());
+      }
+      return matcher;
+    }
+    
+    /**
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * @return an initialized matcher
+     * @noreference This method is for internal matcher initialization by the framework, do not call it manually.
+     * 
+     */
+    public static LoopInInheritence.Matcher create() {
+      return new Matcher();
+    }
+    
+    private static final int POSITION_A = 0;
+    
+    private static final Logger LOGGER = ViatraQueryLoggingUtil.getLogger(LoopInInheritence.Matcher.class);
+    
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    private Matcher() {
+      super(querySpecification());
+    }
+    
+    /**
+     * Returns the set of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return matches represented as a Match object.
+     * 
+     */
+    public Collection<LoopInInheritence.Match> getAllMatches(final EClass pA) {
+      return rawStreamAllMatches(new Object[]{pA}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Returns a stream of all matches of the pattern that conform to the given fixed values of some parameters.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return a stream of matches represented as a Match object.
+     * 
+     */
+    public Stream<LoopInInheritence.Match> streamAllMatches(final EClass pA) {
+      return rawStreamAllMatches(new Object[]{pA});
+    }
+    
+    /**
+     * Returns an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return a match represented as a Match object, or null if no match is found.
+     * 
+     */
+    public Optional<LoopInInheritence.Match> getOneArbitraryMatch(final EClass pA) {
+      return rawGetOneArbitraryMatch(new Object[]{pA});
+    }
+    
+    /**
+     * Indicates whether the given combination of specified pattern parameters constitute a valid pattern match,
+     * under any possible substitution of the unspecified parameters (if any).
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return true if the input is a valid (partial) match of the pattern.
+     * 
+     */
+    public boolean hasMatch(final EClass pA) {
+      return rawHasMatch(new Object[]{pA});
+    }
+    
+    /**
+     * Returns the number of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the number of pattern matches found.
+     * 
+     */
+    public int countMatches(final EClass pA) {
+      return rawCountMatches(new Object[]{pA});
+    }
+    
+    /**
+     * Executes the given processor on an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param processor the action that will process the selected match.
+     * @return true if the pattern has at least one match with the given parameter values, false if the processor was not invoked
+     * 
+     */
+    public boolean forOneArbitraryMatch(final EClass pA, final Consumer<? super LoopInInheritence.Match> processor) {
+      return rawForOneArbitraryMatch(new Object[]{pA}, processor);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public LoopInInheritence.Match newMatch(final EClass pA) {
+      return LoopInInheritence.Match.newMatch(pA);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EClass> rawStreamAllValuesOfa(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_A, parameters).map(EClass.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EClass> getAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EClass> streamAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray());
+    }
+    
+    @Override
+    protected LoopInInheritence.Match tupleToMatch(final Tuple t) {
+      try {
+          return LoopInInheritence.Match.newMatch((EClass) t.get(POSITION_A));
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in tuple not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected LoopInInheritence.Match arrayToMatch(final Object[] match) {
+      try {
+          return LoopInInheritence.Match.newMatch((EClass) match[POSITION_A]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected LoopInInheritence.Match arrayToMatchMutable(final Object[] match) {
+      try {
+          return LoopInInheritence.Match.newMutableMatch((EClass) match[POSITION_A]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    /**
+     * @return the singleton instance of the query specification of this pattern
+     * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+     * 
+     */
+    public static IQuerySpecification<LoopInInheritence.Matcher> querySpecification() {
+      return LoopInInheritence.instance();
+    }
+  }
+  
+  private LoopInInheritence() {
+    super(GeneratedPQuery.INSTANCE);
+  }
+  
+  /**
+   * @return the singleton instance of the query specification
+   * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+   * 
+   */
+  public static LoopInInheritence instance() {
+    try{
+        return LazyHolder.INSTANCE;
+    } catch (ExceptionInInitializerError err) {
+        throw processInitializerError(err);
+    }
+  }
+  
+  @Override
+  protected LoopInInheritence.Matcher instantiate(final ViatraQueryEngine engine) {
+    return LoopInInheritence.Matcher.on(engine);
+  }
+  
+  @Override
+  public LoopInInheritence.Matcher instantiate() {
+    return LoopInInheritence.Matcher.create();
+  }
+  
+  @Override
+  public LoopInInheritence.Match newEmptyMatch() {
+    return LoopInInheritence.Match.newEmptyMatch();
+  }
+  
+  @Override
+  public LoopInInheritence.Match newMatch(final Object... parameters) {
+    return LoopInInheritence.Match.newMatch((org.eclipse.emf.ecore.EClass) parameters[0]);
+  }
+  
+  /**
+   * Inner class allowing the singleton instance of {@link JvmGenericType: ecore.LoopInInheritence (visibility: PUBLIC, simpleName: LoopInInheritence, identifier: ecore.LoopInInheritence, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)} to be created 
+   *     <b>not</b> at the class load time of the outer class, 
+   *     but rather at the first call to {@link JvmGenericType: ecore.LoopInInheritence (visibility: PUBLIC, simpleName: LoopInInheritence, identifier: ecore.LoopInInheritence, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)#instance()}.
+   * 
+   * <p> This workaround is required e.g. to support recursion.
+   * 
+   */
+  private static class LazyHolder {
+    private static final LoopInInheritence INSTANCE = new LoopInInheritence();
+    
+    /**
+     * Statically initializes the query specification <b>after</b> the field {@link #INSTANCE} is assigned.
+     * This initialization order is required to support indirect recursion.
+     * 
+     * <p> The static initializer is defined using a helper field to work around limitations of the code generator.
+     * 
+     */
+    private static final Object STATIC_INITIALIZER = ensureInitialized();
+    
+    public static Object ensureInitialized() {
+      INSTANCE.ensureInitializedInternal();
+      return null;
+    }
+  }
+  
+  private static class GeneratedPQuery extends BaseGeneratedEMFPQuery {
+    private static final LoopInInheritence.GeneratedPQuery INSTANCE = new GeneratedPQuery();
+    
+    private final PParameter parameter_a = new PParameter("a", "org.eclipse.emf.ecore.EClass", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EClass")), PParameterDirection.INOUT);
+    
+    private final List<PParameter> parameters = Arrays.asList(parameter_a);
+    
+    private GeneratedPQuery() {
+      super(PVisibility.PUBLIC);
+    }
+    
+    @Override
+    public String getFullyQualifiedName() {
+      return "ecore.loopInInheritence";
+    }
+    
+    @Override
+    public List<String> getParameterNames() {
+      return Arrays.asList("a");
+    }
+    
+    @Override
+    public List<PParameter> getParameters() {
+      return parameters;
+    }
+    
+    @Override
+    public Set<PBody> doGetContainedBodies() {
+      setEvaluationHints(new QueryEvaluationHint(null, QueryEvaluationHint.BackendRequirement.UNSPECIFIED));
+      Set<PBody> bodies = new LinkedHashSet<>();
+      {
+          PBody body = new PBody(this);
+          PVariable var_a = body.getOrCreateVariableByName("a");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          body.setSymbolicParameters(Arrays.<ExportedParameter>asList(
+             new ExportedParameter(body, var_a, parameter_a)
+          ));
+          //    find directSupertype+(a,a)
+          new BinaryTransitiveClosure(body, Tuples.flatTupleOf(var_a, var_a), DirectSupertype.instance().getInternalQueryRepresentation());
+          bodies.add(body);
+      }
+      {
+          PAnnotation annotation = new PAnnotation("Constraint");
+          annotation.addAttribute("key", Arrays.asList(new Object[] {
+                              new ParameterReference("a")
+                              }));
+          annotation.addAttribute("severity", "error");
+          annotation.addAttribute("message", "error");
+          addAnnotation(annotation);
+      }
+      return bodies;
+    }
+  }
+}
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/NonSymmetricOpposite.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/NonSymmetricOpposite.java
new file mode 100644
index 00000000..d230e3f4
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/NonSymmetricOpposite.java
@@ -0,0 +1,707 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import ecore.Opposite;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.log4j.Logger;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.emf.ecore.EReference;
+import org.eclipse.viatra.query.runtime.api.IPatternMatch;
+import org.eclipse.viatra.query.runtime.api.IQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFPQuery;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.impl.BaseMatcher;
+import org.eclipse.viatra.query.runtime.api.impl.BasePatternMatch;
+import org.eclipse.viatra.query.runtime.emf.types.EClassTransitiveInstancesKey;
+import org.eclipse.viatra.query.runtime.matchers.backend.QueryEvaluationHint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PBody;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PVariable;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.PAnnotation;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.ParameterReference;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.ExportedParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.NegativePatternCall;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.PositivePatternCall;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.TypeConstraint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameterDirection;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PVisibility;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuples;
+import org.eclipse.viatra.query.runtime.util.ViatraQueryLoggingUtil;
+
+/**
+ * A pattern-specific query specification that can instantiate Matcher in a type-safe way.
+ * 
+ * <p>Original source:
+ *         <code><pre>
+ *         {@literal @}Constraint(key={a}, severity="error", message="error")
+ *         pattern nonSymmetricOpposite(a:EReference, b:EReference) {
+ *              find opposite(a,b);
+ *              neg find opposite(b,a);
+ *         }
+ * </pre></code>
+ * 
+ * @see Matcher
+ * @see Match
+ * 
+ */
+@SuppressWarnings("all")
+public final class NonSymmetricOpposite extends BaseGeneratedEMFQuerySpecification<NonSymmetricOpposite.Matcher> {
+  /**
+   * Pattern-specific match representation of the ecore.nonSymmetricOpposite pattern,
+   * to be used in conjunction with {@link Matcher}.
+   * 
+   * <p>Class fields correspond to parameters of the pattern. Fields with value null are considered unassigned.
+   * Each instance is a (possibly partial) substitution of pattern parameters,
+   * usable to represent a match of the pattern in the result of a query,
+   * or to specify the bound (fixed) input parameters when issuing a query.
+   * 
+   * @see Matcher
+   * 
+   */
+  public static abstract class Match extends BasePatternMatch {
+    private EReference fA;
+    
+    private EReference fB;
+    
+    private static List<String> parameterNames = makeImmutableList("a", "b");
+    
+    private Match(final EReference pA, final EReference pB) {
+      this.fA = pA;
+      this.fB = pB;
+    }
+    
+    @Override
+    public Object get(final String parameterName) {
+      if ("a".equals(parameterName)) return this.fA;
+      if ("b".equals(parameterName)) return this.fB;
+      return null;
+    }
+    
+    public EReference getA() {
+      return this.fA;
+    }
+    
+    public EReference getB() {
+      return this.fB;
+    }
+    
+    @Override
+    public boolean set(final String parameterName, final Object newValue) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      if ("a".equals(parameterName) ) {
+          this.fA = (EReference) newValue;
+          return true;
+      }
+      if ("b".equals(parameterName) ) {
+          this.fB = (EReference) newValue;
+          return true;
+      }
+      return false;
+    }
+    
+    public void setA(final EReference pA) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fA = pA;
+    }
+    
+    public void setB(final EReference pB) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fB = pB;
+    }
+    
+    @Override
+    public String patternName() {
+      return "ecore.nonSymmetricOpposite";
+    }
+    
+    @Override
+    public List<String> parameterNames() {
+      return NonSymmetricOpposite.Match.parameterNames;
+    }
+    
+    @Override
+    public Object[] toArray() {
+      return new Object[]{fA, fB};
+    }
+    
+    @Override
+    public NonSymmetricOpposite.Match toImmutable() {
+      return isMutable() ? newMatch(fA, fB) : this;
+    }
+    
+    @Override
+    public String prettyPrint() {
+      StringBuilder result = new StringBuilder();
+      result.append("\"a\"=" + prettyPrintValue(fA) + ", ");
+      result.append("\"b\"=" + prettyPrintValue(fB));
+      return result.toString();
+    }
+    
+    @Override
+    public int hashCode() {
+      return Objects.hash(fA, fB);
+    }
+    
+    @Override
+    public boolean equals(final Object obj) {
+      if (this == obj)
+          return true;
+      if (obj == null) {
+          return false;
+      }
+      if ((obj instanceof NonSymmetricOpposite.Match)) {
+          NonSymmetricOpposite.Match other = (NonSymmetricOpposite.Match) obj;
+          return Objects.equals(fA, other.fA) && Objects.equals(fB, other.fB);
+      } else {
+          // this should be infrequent
+          if (!(obj instanceof IPatternMatch)) {
+              return false;
+          }
+          IPatternMatch otherSig  = (IPatternMatch) obj;
+          return Objects.equals(specification(), otherSig.specification()) && Arrays.deepEquals(toArray(), otherSig.toArray());
+      }
+    }
+    
+    @Override
+    public NonSymmetricOpposite specification() {
+      return NonSymmetricOpposite.instance();
+    }
+    
+    /**
+     * Returns an empty, mutable match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @return the empty match.
+     * 
+     */
+    public static NonSymmetricOpposite.Match newEmptyMatch() {
+      return new Mutable(null, null);
+    }
+    
+    /**
+     * Returns a mutable (partial) match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the new, mutable (partial) match object.
+     * 
+     */
+    public static NonSymmetricOpposite.Match newMutableMatch(final EReference pA, final EReference pB) {
+      return new Mutable(pA, pB);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public static NonSymmetricOpposite.Match newMatch(final EReference pA, final EReference pB) {
+      return new Immutable(pA, pB);
+    }
+    
+    private static final class Mutable extends NonSymmetricOpposite.Match {
+      Mutable(final EReference pA, final EReference pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return true;
+      }
+    }
+    
+    private static final class Immutable extends NonSymmetricOpposite.Match {
+      Immutable(final EReference pA, final EReference pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return false;
+      }
+    }
+  }
+  
+  /**
+   * Generated pattern matcher API of the ecore.nonSymmetricOpposite pattern,
+   * providing pattern-specific query methods.
+   * 
+   * <p>Use the pattern matcher on a given model via {@link #on(ViatraQueryEngine)},
+   * e.g. in conjunction with {@link ViatraQueryEngine#on(QueryScope)}.
+   * 
+   * <p>Matches of the pattern will be represented as {@link Match}.
+   * 
+   * <p>Original source:
+   * <code><pre>
+   * {@literal @}Constraint(key={a}, severity="error", message="error")
+   * pattern nonSymmetricOpposite(a:EReference, b:EReference) {
+   *    find opposite(a,b);
+   *    neg find opposite(b,a);
+   * }
+   * </pre></code>
+   * 
+   * @see Match
+   * @see NonSymmetricOpposite
+   * 
+   */
+  public static class Matcher extends BaseMatcher<NonSymmetricOpposite.Match> {
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    public static NonSymmetricOpposite.Matcher on(final ViatraQueryEngine engine) {
+      // check if matcher already exists
+      Matcher matcher = engine.getExistingMatcher(querySpecification());
+      if (matcher == null) {
+          matcher = (Matcher)engine.getMatcher(querySpecification());
+      }
+      return matcher;
+    }
+    
+    /**
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * @return an initialized matcher
+     * @noreference This method is for internal matcher initialization by the framework, do not call it manually.
+     * 
+     */
+    public static NonSymmetricOpposite.Matcher create() {
+      return new Matcher();
+    }
+    
+    private static final int POSITION_A = 0;
+    
+    private static final int POSITION_B = 1;
+    
+    private static final Logger LOGGER = ViatraQueryLoggingUtil.getLogger(NonSymmetricOpposite.Matcher.class);
+    
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    private Matcher() {
+      super(querySpecification());
+    }
+    
+    /**
+     * Returns the set of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return matches represented as a Match object.
+     * 
+     */
+    public Collection<NonSymmetricOpposite.Match> getAllMatches(final EReference pA, final EReference pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Returns a stream of all matches of the pattern that conform to the given fixed values of some parameters.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a stream of matches represented as a Match object.
+     * 
+     */
+    public Stream<NonSymmetricOpposite.Match> streamAllMatches(final EReference pA, final EReference pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a match represented as a Match object, or null if no match is found.
+     * 
+     */
+    public Optional<NonSymmetricOpposite.Match> getOneArbitraryMatch(final EReference pA, final EReference pB) {
+      return rawGetOneArbitraryMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Indicates whether the given combination of specified pattern parameters constitute a valid pattern match,
+     * under any possible substitution of the unspecified parameters (if any).
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return true if the input is a valid (partial) match of the pattern.
+     * 
+     */
+    public boolean hasMatch(final EReference pA, final EReference pB) {
+      return rawHasMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns the number of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the number of pattern matches found.
+     * 
+     */
+    public int countMatches(final EReference pA, final EReference pB) {
+      return rawCountMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Executes the given processor on an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @param processor the action that will process the selected match.
+     * @return true if the pattern has at least one match with the given parameter values, false if the processor was not invoked
+     * 
+     */
+    public boolean forOneArbitraryMatch(final EReference pA, final EReference pB, final Consumer<? super NonSymmetricOpposite.Match> processor) {
+      return rawForOneArbitraryMatch(new Object[]{pA, pB}, processor);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public NonSymmetricOpposite.Match newMatch(final EReference pA, final EReference pB) {
+      return NonSymmetricOpposite.Match.newMatch(pA, pB);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EReference> rawStreamAllValuesOfa(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_A, parameters).map(EReference.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa(final NonSymmetricOpposite.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa(final EReference pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa(final NonSymmetricOpposite.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa(final EReference pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EReference> rawStreamAllValuesOfb(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_B, parameters).map(EReference.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb(final NonSymmetricOpposite.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb(final EReference pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb(final NonSymmetricOpposite.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb(final EReference pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null}).collect(Collectors.toSet());
+    }
+    
+    @Override
+    protected NonSymmetricOpposite.Match tupleToMatch(final Tuple t) {
+      try {
+          return NonSymmetricOpposite.Match.newMatch((EReference) t.get(POSITION_A), (EReference) t.get(POSITION_B));
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in tuple not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected NonSymmetricOpposite.Match arrayToMatch(final Object[] match) {
+      try {
+          return NonSymmetricOpposite.Match.newMatch((EReference) match[POSITION_A], (EReference) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected NonSymmetricOpposite.Match arrayToMatchMutable(final Object[] match) {
+      try {
+          return NonSymmetricOpposite.Match.newMutableMatch((EReference) match[POSITION_A], (EReference) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    /**
+     * @return the singleton instance of the query specification of this pattern
+     * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+     * 
+     */
+    public static IQuerySpecification<NonSymmetricOpposite.Matcher> querySpecification() {
+      return NonSymmetricOpposite.instance();
+    }
+  }
+  
+  private NonSymmetricOpposite() {
+    super(GeneratedPQuery.INSTANCE);
+  }
+  
+  /**
+   * @return the singleton instance of the query specification
+   * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+   * 
+   */
+  public static NonSymmetricOpposite instance() {
+    try{
+        return LazyHolder.INSTANCE;
+    } catch (ExceptionInInitializerError err) {
+        throw processInitializerError(err);
+    }
+  }
+  
+  @Override
+  protected NonSymmetricOpposite.Matcher instantiate(final ViatraQueryEngine engine) {
+    return NonSymmetricOpposite.Matcher.on(engine);
+  }
+  
+  @Override
+  public NonSymmetricOpposite.Matcher instantiate() {
+    return NonSymmetricOpposite.Matcher.create();
+  }
+  
+  @Override
+  public NonSymmetricOpposite.Match newEmptyMatch() {
+    return NonSymmetricOpposite.Match.newEmptyMatch();
+  }
+  
+  @Override
+  public NonSymmetricOpposite.Match newMatch(final Object... parameters) {
+    return NonSymmetricOpposite.Match.newMatch((org.eclipse.emf.ecore.EReference) parameters[0], (org.eclipse.emf.ecore.EReference) parameters[1]);
+  }
+  
+  /**
+   * Inner class allowing the singleton instance of {@link JvmGenericType: ecore.NonSymmetricOpposite (visibility: PUBLIC, simpleName: NonSymmetricOpposite, identifier: ecore.NonSymmetricOpposite, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)} to be created 
+   *     <b>not</b> at the class load time of the outer class, 
+   *     but rather at the first call to {@link JvmGenericType: ecore.NonSymmetricOpposite (visibility: PUBLIC, simpleName: NonSymmetricOpposite, identifier: ecore.NonSymmetricOpposite, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)#instance()}.
+   * 
+   * <p> This workaround is required e.g. to support recursion.
+   * 
+   */
+  private static class LazyHolder {
+    private static final NonSymmetricOpposite INSTANCE = new NonSymmetricOpposite();
+    
+    /**
+     * Statically initializes the query specification <b>after</b> the field {@link #INSTANCE} is assigned.
+     * This initialization order is required to support indirect recursion.
+     * 
+     * <p> The static initializer is defined using a helper field to work around limitations of the code generator.
+     * 
+     */
+    private static final Object STATIC_INITIALIZER = ensureInitialized();
+    
+    public static Object ensureInitialized() {
+      INSTANCE.ensureInitializedInternal();
+      return null;
+    }
+  }
+  
+  private static class GeneratedPQuery extends BaseGeneratedEMFPQuery {
+    private static final NonSymmetricOpposite.GeneratedPQuery INSTANCE = new GeneratedPQuery();
+    
+    private final PParameter parameter_a = new PParameter("a", "org.eclipse.emf.ecore.EReference", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EReference")), PParameterDirection.INOUT);
+    
+    private final PParameter parameter_b = new PParameter("b", "org.eclipse.emf.ecore.EReference", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EReference")), PParameterDirection.INOUT);
+    
+    private final List<PParameter> parameters = Arrays.asList(parameter_a, parameter_b);
+    
+    private GeneratedPQuery() {
+      super(PVisibility.PUBLIC);
+    }
+    
+    @Override
+    public String getFullyQualifiedName() {
+      return "ecore.nonSymmetricOpposite";
+    }
+    
+    @Override
+    public List<String> getParameterNames() {
+      return Arrays.asList("a","b");
+    }
+    
+    @Override
+    public List<PParameter> getParameters() {
+      return parameters;
+    }
+    
+    @Override
+    public Set<PBody> doGetContainedBodies() {
+      setEvaluationHints(new QueryEvaluationHint(null, QueryEvaluationHint.BackendRequirement.UNSPECIFIED));
+      Set<PBody> bodies = new LinkedHashSet<>();
+      {
+          PBody body = new PBody(this);
+          PVariable var_a = body.getOrCreateVariableByName("a");
+          PVariable var_b = body.getOrCreateVariableByName("b");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var_b), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          body.setSymbolicParameters(Arrays.<ExportedParameter>asList(
+             new ExportedParameter(body, var_a, parameter_a),
+             new ExportedParameter(body, var_b, parameter_b)
+          ));
+          //    find opposite(a,b)
+          new PositivePatternCall(body, Tuples.flatTupleOf(var_a, var_b), Opposite.instance().getInternalQueryRepresentation());
+          //    neg find opposite(b,a)
+          new NegativePatternCall(body, Tuples.flatTupleOf(var_b, var_a), Opposite.instance().getInternalQueryRepresentation());
+          bodies.add(body);
+      }
+      {
+          PAnnotation annotation = new PAnnotation("Constraint");
+          annotation.addAttribute("key", Arrays.asList(new Object[] {
+                              new ParameterReference("a")
+                              }));
+          annotation.addAttribute("severity", "error");
+          annotation.addAttribute("message", "error");
+          addAnnotation(annotation);
+      }
+      return bodies;
+    }
+  }
+}
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Opposite.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Opposite.java
new file mode 100644
index 00000000..d826f072
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/Opposite.java
@@ -0,0 +1,693 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.log4j.Logger;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.emf.ecore.EReference;
+import org.eclipse.viatra.query.runtime.api.IPatternMatch;
+import org.eclipse.viatra.query.runtime.api.IQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFPQuery;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.impl.BaseMatcher;
+import org.eclipse.viatra.query.runtime.api.impl.BasePatternMatch;
+import org.eclipse.viatra.query.runtime.emf.types.EClassTransitiveInstancesKey;
+import org.eclipse.viatra.query.runtime.emf.types.EStructuralFeatureInstancesKey;
+import org.eclipse.viatra.query.runtime.matchers.backend.QueryEvaluationHint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PBody;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PVariable;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.Equality;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.ExportedParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.TypeConstraint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameterDirection;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PVisibility;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuples;
+import org.eclipse.viatra.query.runtime.util.ViatraQueryLoggingUtil;
+
+/**
+ * A pattern-specific query specification that can instantiate Matcher in a type-safe way.
+ * 
+ * <p>Original source:
+ *         <code><pre>
+ *         pattern opposite(a:EReference, b: EReference) {
+ *              EReference.eOpposite(a,b);
+ *         }
+ * </pre></code>
+ * 
+ * @see Matcher
+ * @see Match
+ * 
+ */
+@SuppressWarnings("all")
+public final class Opposite extends BaseGeneratedEMFQuerySpecification<Opposite.Matcher> {
+  /**
+   * Pattern-specific match representation of the ecore.opposite pattern,
+   * to be used in conjunction with {@link Matcher}.
+   * 
+   * <p>Class fields correspond to parameters of the pattern. Fields with value null are considered unassigned.
+   * Each instance is a (possibly partial) substitution of pattern parameters,
+   * usable to represent a match of the pattern in the result of a query,
+   * or to specify the bound (fixed) input parameters when issuing a query.
+   * 
+   * @see Matcher
+   * 
+   */
+  public static abstract class Match extends BasePatternMatch {
+    private EReference fA;
+    
+    private EReference fB;
+    
+    private static List<String> parameterNames = makeImmutableList("a", "b");
+    
+    private Match(final EReference pA, final EReference pB) {
+      this.fA = pA;
+      this.fB = pB;
+    }
+    
+    @Override
+    public Object get(final String parameterName) {
+      if ("a".equals(parameterName)) return this.fA;
+      if ("b".equals(parameterName)) return this.fB;
+      return null;
+    }
+    
+    public EReference getA() {
+      return this.fA;
+    }
+    
+    public EReference getB() {
+      return this.fB;
+    }
+    
+    @Override
+    public boolean set(final String parameterName, final Object newValue) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      if ("a".equals(parameterName) ) {
+          this.fA = (EReference) newValue;
+          return true;
+      }
+      if ("b".equals(parameterName) ) {
+          this.fB = (EReference) newValue;
+          return true;
+      }
+      return false;
+    }
+    
+    public void setA(final EReference pA) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fA = pA;
+    }
+    
+    public void setB(final EReference pB) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fB = pB;
+    }
+    
+    @Override
+    public String patternName() {
+      return "ecore.opposite";
+    }
+    
+    @Override
+    public List<String> parameterNames() {
+      return Opposite.Match.parameterNames;
+    }
+    
+    @Override
+    public Object[] toArray() {
+      return new Object[]{fA, fB};
+    }
+    
+    @Override
+    public Opposite.Match toImmutable() {
+      return isMutable() ? newMatch(fA, fB) : this;
+    }
+    
+    @Override
+    public String prettyPrint() {
+      StringBuilder result = new StringBuilder();
+      result.append("\"a\"=" + prettyPrintValue(fA) + ", ");
+      result.append("\"b\"=" + prettyPrintValue(fB));
+      return result.toString();
+    }
+    
+    @Override
+    public int hashCode() {
+      return Objects.hash(fA, fB);
+    }
+    
+    @Override
+    public boolean equals(final Object obj) {
+      if (this == obj)
+          return true;
+      if (obj == null) {
+          return false;
+      }
+      if ((obj instanceof Opposite.Match)) {
+          Opposite.Match other = (Opposite.Match) obj;
+          return Objects.equals(fA, other.fA) && Objects.equals(fB, other.fB);
+      } else {
+          // this should be infrequent
+          if (!(obj instanceof IPatternMatch)) {
+              return false;
+          }
+          IPatternMatch otherSig  = (IPatternMatch) obj;
+          return Objects.equals(specification(), otherSig.specification()) && Arrays.deepEquals(toArray(), otherSig.toArray());
+      }
+    }
+    
+    @Override
+    public Opposite specification() {
+      return Opposite.instance();
+    }
+    
+    /**
+     * Returns an empty, mutable match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @return the empty match.
+     * 
+     */
+    public static Opposite.Match newEmptyMatch() {
+      return new Mutable(null, null);
+    }
+    
+    /**
+     * Returns a mutable (partial) match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the new, mutable (partial) match object.
+     * 
+     */
+    public static Opposite.Match newMutableMatch(final EReference pA, final EReference pB) {
+      return new Mutable(pA, pB);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public static Opposite.Match newMatch(final EReference pA, final EReference pB) {
+      return new Immutable(pA, pB);
+    }
+    
+    private static final class Mutable extends Opposite.Match {
+      Mutable(final EReference pA, final EReference pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return true;
+      }
+    }
+    
+    private static final class Immutable extends Opposite.Match {
+      Immutable(final EReference pA, final EReference pB) {
+        super(pA, pB);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return false;
+      }
+    }
+  }
+  
+  /**
+   * Generated pattern matcher API of the ecore.opposite pattern,
+   * providing pattern-specific query methods.
+   * 
+   * <p>Use the pattern matcher on a given model via {@link #on(ViatraQueryEngine)},
+   * e.g. in conjunction with {@link ViatraQueryEngine#on(QueryScope)}.
+   * 
+   * <p>Matches of the pattern will be represented as {@link Match}.
+   * 
+   * <p>Original source:
+   * <code><pre>
+   * pattern opposite(a:EReference, b: EReference) {
+   *    EReference.eOpposite(a,b);
+   * }
+   * </pre></code>
+   * 
+   * @see Match
+   * @see Opposite
+   * 
+   */
+  public static class Matcher extends BaseMatcher<Opposite.Match> {
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    public static Opposite.Matcher on(final ViatraQueryEngine engine) {
+      // check if matcher already exists
+      Matcher matcher = engine.getExistingMatcher(querySpecification());
+      if (matcher == null) {
+          matcher = (Matcher)engine.getMatcher(querySpecification());
+      }
+      return matcher;
+    }
+    
+    /**
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * @return an initialized matcher
+     * @noreference This method is for internal matcher initialization by the framework, do not call it manually.
+     * 
+     */
+    public static Opposite.Matcher create() {
+      return new Matcher();
+    }
+    
+    private static final int POSITION_A = 0;
+    
+    private static final int POSITION_B = 1;
+    
+    private static final Logger LOGGER = ViatraQueryLoggingUtil.getLogger(Opposite.Matcher.class);
+    
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    private Matcher() {
+      super(querySpecification());
+    }
+    
+    /**
+     * Returns the set of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return matches represented as a Match object.
+     * 
+     */
+    public Collection<Opposite.Match> getAllMatches(final EReference pA, final EReference pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Returns a stream of all matches of the pattern that conform to the given fixed values of some parameters.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a stream of matches represented as a Match object.
+     * 
+     */
+    public Stream<Opposite.Match> streamAllMatches(final EReference pA, final EReference pB) {
+      return rawStreamAllMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return a match represented as a Match object, or null if no match is found.
+     * 
+     */
+    public Optional<Opposite.Match> getOneArbitraryMatch(final EReference pA, final EReference pB) {
+      return rawGetOneArbitraryMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Indicates whether the given combination of specified pattern parameters constitute a valid pattern match,
+     * under any possible substitution of the unspecified parameters (if any).
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return true if the input is a valid (partial) match of the pattern.
+     * 
+     */
+    public boolean hasMatch(final EReference pA, final EReference pB) {
+      return rawHasMatch(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Returns the number of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the number of pattern matches found.
+     * 
+     */
+    public int countMatches(final EReference pA, final EReference pB) {
+      return rawCountMatches(new Object[]{pA, pB});
+    }
+    
+    /**
+     * Executes the given processor on an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @param processor the action that will process the selected match.
+     * @return true if the pattern has at least one match with the given parameter values, false if the processor was not invoked
+     * 
+     */
+    public boolean forOneArbitraryMatch(final EReference pA, final EReference pB, final Consumer<? super Opposite.Match> processor) {
+      return rawForOneArbitraryMatch(new Object[]{pA, pB}, processor);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param pB the fixed value of pattern parameter b, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public Opposite.Match newMatch(final EReference pA, final EReference pB) {
+      return Opposite.Match.newMatch(pA, pB);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EReference> rawStreamAllValuesOfa(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_A, parameters).map(EReference.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa(final Opposite.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa(final EReference pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa(final Opposite.Match partialMatch) {
+      return rawStreamAllValuesOfa(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa(final EReference pB) {
+      return rawStreamAllValuesOfa(new Object[]{null, pB}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EReference> rawStreamAllValuesOfb(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_B, parameters).map(EReference.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb() {
+      return rawStreamAllValuesOfb(emptyArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb(final Opposite.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     *      
+     * @return the Stream of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfb(final EReference pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null});
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb(final Opposite.Match partialMatch) {
+      return rawStreamAllValuesOfb(partialMatch.toArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for b.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfb(final EReference pA) {
+      return rawStreamAllValuesOfb(new Object[]{pA, null}).collect(Collectors.toSet());
+    }
+    
+    @Override
+    protected Opposite.Match tupleToMatch(final Tuple t) {
+      try {
+          return Opposite.Match.newMatch((EReference) t.get(POSITION_A), (EReference) t.get(POSITION_B));
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in tuple not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected Opposite.Match arrayToMatch(final Object[] match) {
+      try {
+          return Opposite.Match.newMatch((EReference) match[POSITION_A], (EReference) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected Opposite.Match arrayToMatchMutable(final Object[] match) {
+      try {
+          return Opposite.Match.newMutableMatch((EReference) match[POSITION_A], (EReference) match[POSITION_B]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    /**
+     * @return the singleton instance of the query specification of this pattern
+     * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+     * 
+     */
+    public static IQuerySpecification<Opposite.Matcher> querySpecification() {
+      return Opposite.instance();
+    }
+  }
+  
+  private Opposite() {
+    super(GeneratedPQuery.INSTANCE);
+  }
+  
+  /**
+   * @return the singleton instance of the query specification
+   * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+   * 
+   */
+  public static Opposite instance() {
+    try{
+        return LazyHolder.INSTANCE;
+    } catch (ExceptionInInitializerError err) {
+        throw processInitializerError(err);
+    }
+  }
+  
+  @Override
+  protected Opposite.Matcher instantiate(final ViatraQueryEngine engine) {
+    return Opposite.Matcher.on(engine);
+  }
+  
+  @Override
+  public Opposite.Matcher instantiate() {
+    return Opposite.Matcher.create();
+  }
+  
+  @Override
+  public Opposite.Match newEmptyMatch() {
+    return Opposite.Match.newEmptyMatch();
+  }
+  
+  @Override
+  public Opposite.Match newMatch(final Object... parameters) {
+    return Opposite.Match.newMatch((org.eclipse.emf.ecore.EReference) parameters[0], (org.eclipse.emf.ecore.EReference) parameters[1]);
+  }
+  
+  /**
+   * Inner class allowing the singleton instance of {@link JvmGenericType: ecore.Opposite (visibility: PUBLIC, simpleName: Opposite, identifier: ecore.Opposite, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)} to be created 
+   *     <b>not</b> at the class load time of the outer class, 
+   *     but rather at the first call to {@link JvmGenericType: ecore.Opposite (visibility: PUBLIC, simpleName: Opposite, identifier: ecore.Opposite, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)#instance()}.
+   * 
+   * <p> This workaround is required e.g. to support recursion.
+   * 
+   */
+  private static class LazyHolder {
+    private static final Opposite INSTANCE = new Opposite();
+    
+    /**
+     * Statically initializes the query specification <b>after</b> the field {@link #INSTANCE} is assigned.
+     * This initialization order is required to support indirect recursion.
+     * 
+     * <p> The static initializer is defined using a helper field to work around limitations of the code generator.
+     * 
+     */
+    private static final Object STATIC_INITIALIZER = ensureInitialized();
+    
+    public static Object ensureInitialized() {
+      INSTANCE.ensureInitializedInternal();
+      return null;
+    }
+  }
+  
+  private static class GeneratedPQuery extends BaseGeneratedEMFPQuery {
+    private static final Opposite.GeneratedPQuery INSTANCE = new GeneratedPQuery();
+    
+    private final PParameter parameter_a = new PParameter("a", "org.eclipse.emf.ecore.EReference", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EReference")), PParameterDirection.INOUT);
+    
+    private final PParameter parameter_b = new PParameter("b", "org.eclipse.emf.ecore.EReference", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EReference")), PParameterDirection.INOUT);
+    
+    private final List<PParameter> parameters = Arrays.asList(parameter_a, parameter_b);
+    
+    private GeneratedPQuery() {
+      super(PVisibility.PUBLIC);
+    }
+    
+    @Override
+    public String getFullyQualifiedName() {
+      return "ecore.opposite";
+    }
+    
+    @Override
+    public List<String> getParameterNames() {
+      return Arrays.asList("a","b");
+    }
+    
+    @Override
+    public List<PParameter> getParameters() {
+      return parameters;
+    }
+    
+    @Override
+    public Set<PBody> doGetContainedBodies() {
+      setEvaluationHints(new QueryEvaluationHint(null, QueryEvaluationHint.BackendRequirement.UNSPECIFIED));
+      Set<PBody> bodies = new LinkedHashSet<>();
+      {
+          PBody body = new PBody(this);
+          PVariable var_a = body.getOrCreateVariableByName("a");
+          PVariable var_b = body.getOrCreateVariableByName("b");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var_b), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          body.setSymbolicParameters(Arrays.<ExportedParameter>asList(
+             new ExportedParameter(body, var_a, parameter_a),
+             new ExportedParameter(body, var_b, parameter_b)
+          ));
+          //    EReference.eOpposite(a,b)
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          PVariable var__virtual_0_ = body.getOrCreateVariableByName(".virtual{0}");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a, var__virtual_0_), new EStructuralFeatureInstancesKey(getFeatureLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference", "eOpposite")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var__virtual_0_), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          new Equality(body, var__virtual_0_, var_b);
+          bodies.add(body);
+      }
+      return bodies;
+    }
+  }
+}
diff --git a/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/OppositeDifferentClass.java b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/OppositeDifferentClass.java
new file mode 100644
index 00000000..3a0df648
--- /dev/null
+++ b/Metrics/Metrics-Calculation/ca.mcgill.ecse.dslreasoner.realistic.metrics.calculator/constraints/ecore/OppositeDifferentClass.java
@@ -0,0 +1,577 @@
+/**
+ * Generated from platform:/resource/SocialNetwork_plugin/queries/ecore/Ecore.vql
+ */
+package ecore;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.log4j.Logger;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.emf.ecore.EReference;
+import org.eclipse.viatra.query.runtime.api.IPatternMatch;
+import org.eclipse.viatra.query.runtime.api.IQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.ViatraQueryEngine;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFPQuery;
+import org.eclipse.viatra.query.runtime.api.impl.BaseGeneratedEMFQuerySpecification;
+import org.eclipse.viatra.query.runtime.api.impl.BaseMatcher;
+import org.eclipse.viatra.query.runtime.api.impl.BasePatternMatch;
+import org.eclipse.viatra.query.runtime.emf.types.EClassTransitiveInstancesKey;
+import org.eclipse.viatra.query.runtime.emf.types.EStructuralFeatureInstancesKey;
+import org.eclipse.viatra.query.runtime.matchers.backend.QueryEvaluationHint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PBody;
+import org.eclipse.viatra.query.runtime.matchers.psystem.PVariable;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.PAnnotation;
+import org.eclipse.viatra.query.runtime.matchers.psystem.annotations.ParameterReference;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.Equality;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.ExportedParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicdeferred.Inequality;
+import org.eclipse.viatra.query.runtime.matchers.psystem.basicenumerables.TypeConstraint;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameter;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PParameterDirection;
+import org.eclipse.viatra.query.runtime.matchers.psystem.queries.PVisibility;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuples;
+import org.eclipse.viatra.query.runtime.util.ViatraQueryLoggingUtil;
+
+/**
+ * A pattern-specific query specification that can instantiate Matcher in a type-safe way.
+ * 
+ * <p>Original source:
+ *         <code><pre>
+ *         {@literal @}Constraint(key={a}, severity="error", message="error")
+ *         pattern oppositeDifferentClass(a:EReference) {
+ *              EReference.eOpposite(a,b);
+ *              EReference.eContainingClass(a,aContaining);
+ *              EReference.eType(b,bTarget);
+ *              aContaining != bTarget;
+ *         }
+ * </pre></code>
+ * 
+ * @see Matcher
+ * @see Match
+ * 
+ */
+@SuppressWarnings("all")
+public final class OppositeDifferentClass extends BaseGeneratedEMFQuerySpecification<OppositeDifferentClass.Matcher> {
+  /**
+   * Pattern-specific match representation of the ecore.oppositeDifferentClass pattern,
+   * to be used in conjunction with {@link Matcher}.
+   * 
+   * <p>Class fields correspond to parameters of the pattern. Fields with value null are considered unassigned.
+   * Each instance is a (possibly partial) substitution of pattern parameters,
+   * usable to represent a match of the pattern in the result of a query,
+   * or to specify the bound (fixed) input parameters when issuing a query.
+   * 
+   * @see Matcher
+   * 
+   */
+  public static abstract class Match extends BasePatternMatch {
+    private EReference fA;
+    
+    private static List<String> parameterNames = makeImmutableList("a");
+    
+    private Match(final EReference pA) {
+      this.fA = pA;
+    }
+    
+    @Override
+    public Object get(final String parameterName) {
+      if ("a".equals(parameterName)) return this.fA;
+      return null;
+    }
+    
+    public EReference getA() {
+      return this.fA;
+    }
+    
+    @Override
+    public boolean set(final String parameterName, final Object newValue) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      if ("a".equals(parameterName) ) {
+          this.fA = (EReference) newValue;
+          return true;
+      }
+      return false;
+    }
+    
+    public void setA(final EReference pA) {
+      if (!isMutable()) throw new java.lang.UnsupportedOperationException();
+      this.fA = pA;
+    }
+    
+    @Override
+    public String patternName() {
+      return "ecore.oppositeDifferentClass";
+    }
+    
+    @Override
+    public List<String> parameterNames() {
+      return OppositeDifferentClass.Match.parameterNames;
+    }
+    
+    @Override
+    public Object[] toArray() {
+      return new Object[]{fA};
+    }
+    
+    @Override
+    public OppositeDifferentClass.Match toImmutable() {
+      return isMutable() ? newMatch(fA) : this;
+    }
+    
+    @Override
+    public String prettyPrint() {
+      StringBuilder result = new StringBuilder();
+      result.append("\"a\"=" + prettyPrintValue(fA));
+      return result.toString();
+    }
+    
+    @Override
+    public int hashCode() {
+      return Objects.hash(fA);
+    }
+    
+    @Override
+    public boolean equals(final Object obj) {
+      if (this == obj)
+          return true;
+      if (obj == null) {
+          return false;
+      }
+      if ((obj instanceof OppositeDifferentClass.Match)) {
+          OppositeDifferentClass.Match other = (OppositeDifferentClass.Match) obj;
+          return Objects.equals(fA, other.fA);
+      } else {
+          // this should be infrequent
+          if (!(obj instanceof IPatternMatch)) {
+              return false;
+          }
+          IPatternMatch otherSig  = (IPatternMatch) obj;
+          return Objects.equals(specification(), otherSig.specification()) && Arrays.deepEquals(toArray(), otherSig.toArray());
+      }
+    }
+    
+    @Override
+    public OppositeDifferentClass specification() {
+      return OppositeDifferentClass.instance();
+    }
+    
+    /**
+     * Returns an empty, mutable match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @return the empty match.
+     * 
+     */
+    public static OppositeDifferentClass.Match newEmptyMatch() {
+      return new Mutable(null);
+    }
+    
+    /**
+     * Returns a mutable (partial) match.
+     * Fields of the mutable match can be filled to create a partial match, usable as matcher input.
+     * 
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the new, mutable (partial) match object.
+     * 
+     */
+    public static OppositeDifferentClass.Match newMutableMatch(final EReference pA) {
+      return new Mutable(pA);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public static OppositeDifferentClass.Match newMatch(final EReference pA) {
+      return new Immutable(pA);
+    }
+    
+    private static final class Mutable extends OppositeDifferentClass.Match {
+      Mutable(final EReference pA) {
+        super(pA);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return true;
+      }
+    }
+    
+    private static final class Immutable extends OppositeDifferentClass.Match {
+      Immutable(final EReference pA) {
+        super(pA);
+      }
+      
+      @Override
+      public boolean isMutable() {
+        return false;
+      }
+    }
+  }
+  
+  /**
+   * Generated pattern matcher API of the ecore.oppositeDifferentClass pattern,
+   * providing pattern-specific query methods.
+   * 
+   * <p>Use the pattern matcher on a given model via {@link #on(ViatraQueryEngine)},
+   * e.g. in conjunction with {@link ViatraQueryEngine#on(QueryScope)}.
+   * 
+   * <p>Matches of the pattern will be represented as {@link Match}.
+   * 
+   * <p>Original source:
+   * <code><pre>
+   * {@literal @}Constraint(key={a}, severity="error", message="error")
+   * pattern oppositeDifferentClass(a:EReference) {
+   *    EReference.eOpposite(a,b);
+   *    EReference.eContainingClass(a,aContaining);
+   *    EReference.eType(b,bTarget);
+   *    aContaining != bTarget;
+   * }
+   * </pre></code>
+   * 
+   * @see Match
+   * @see OppositeDifferentClass
+   * 
+   */
+  public static class Matcher extends BaseMatcher<OppositeDifferentClass.Match> {
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    public static OppositeDifferentClass.Matcher on(final ViatraQueryEngine engine) {
+      // check if matcher already exists
+      Matcher matcher = engine.getExistingMatcher(querySpecification());
+      if (matcher == null) {
+          matcher = (Matcher)engine.getMatcher(querySpecification());
+      }
+      return matcher;
+    }
+    
+    /**
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * @return an initialized matcher
+     * @noreference This method is for internal matcher initialization by the framework, do not call it manually.
+     * 
+     */
+    public static OppositeDifferentClass.Matcher create() {
+      return new Matcher();
+    }
+    
+    private static final int POSITION_A = 0;
+    
+    private static final Logger LOGGER = ViatraQueryLoggingUtil.getLogger(OppositeDifferentClass.Matcher.class);
+    
+    /**
+     * Initializes the pattern matcher within an existing VIATRA Query engine.
+     * If the pattern matcher is already constructed in the engine, only a light-weight reference is returned.
+     * 
+     * @param engine the existing VIATRA Query engine in which this matcher will be created.
+     * @throws ViatraQueryRuntimeException if an error occurs during pattern matcher creation
+     * 
+     */
+    private Matcher() {
+      super(querySpecification());
+    }
+    
+    /**
+     * Returns the set of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return matches represented as a Match object.
+     * 
+     */
+    public Collection<OppositeDifferentClass.Match> getAllMatches(final EReference pA) {
+      return rawStreamAllMatches(new Object[]{pA}).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Returns a stream of all matches of the pattern that conform to the given fixed values of some parameters.
+     * </p>
+     * <strong>NOTE</strong>: It is important not to modify the source model while the stream is being processed.
+     * If the match set of the pattern changes during processing, the contents of the stream is <strong>undefined</strong>.
+     * In such cases, either rely on {@link #getAllMatches()} or collect the results of the stream in end-user code.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return a stream of matches represented as a Match object.
+     * 
+     */
+    public Stream<OppositeDifferentClass.Match> streamAllMatches(final EReference pA) {
+      return rawStreamAllMatches(new Object[]{pA});
+    }
+    
+    /**
+     * Returns an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return a match represented as a Match object, or null if no match is found.
+     * 
+     */
+    public Optional<OppositeDifferentClass.Match> getOneArbitraryMatch(final EReference pA) {
+      return rawGetOneArbitraryMatch(new Object[]{pA});
+    }
+    
+    /**
+     * Indicates whether the given combination of specified pattern parameters constitute a valid pattern match,
+     * under any possible substitution of the unspecified parameters (if any).
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return true if the input is a valid (partial) match of the pattern.
+     * 
+     */
+    public boolean hasMatch(final EReference pA) {
+      return rawHasMatch(new Object[]{pA});
+    }
+    
+    /**
+     * Returns the number of all matches of the pattern that conform to the given fixed values of some parameters.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the number of pattern matches found.
+     * 
+     */
+    public int countMatches(final EReference pA) {
+      return rawCountMatches(new Object[]{pA});
+    }
+    
+    /**
+     * Executes the given processor on an arbitrarily chosen match of the pattern that conforms to the given fixed values of some parameters.
+     * Neither determinism nor randomness of selection is guaranteed.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @param processor the action that will process the selected match.
+     * @return true if the pattern has at least one match with the given parameter values, false if the processor was not invoked
+     * 
+     */
+    public boolean forOneArbitraryMatch(final EReference pA, final Consumer<? super OppositeDifferentClass.Match> processor) {
+      return rawForOneArbitraryMatch(new Object[]{pA}, processor);
+    }
+    
+    /**
+     * Returns a new (partial) match.
+     * This can be used e.g. to call the matcher with a partial match.
+     * <p>The returned match will be immutable. Use {@link #newEmptyMatch()} to obtain a mutable match object.
+     * @param pA the fixed value of pattern parameter a, or null if not bound.
+     * @return the (partial) match object.
+     * 
+     */
+    public OppositeDifferentClass.Match newMatch(final EReference pA) {
+      return OppositeDifferentClass.Match.newMatch(pA);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    protected Stream<EReference> rawStreamAllValuesOfa(final Object[] parameters) {
+      return rawStreamAllValues(POSITION_A, parameters).map(EReference.class::cast);
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Set<EReference> getAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray()).collect(Collectors.toSet());
+    }
+    
+    /**
+     * Retrieve the set of values that occur in matches for a.
+     * @return the Set of all values or empty set if there are no matches
+     * 
+     */
+    public Stream<EReference> streamAllValuesOfa() {
+      return rawStreamAllValuesOfa(emptyArray());
+    }
+    
+    @Override
+    protected OppositeDifferentClass.Match tupleToMatch(final Tuple t) {
+      try {
+          return OppositeDifferentClass.Match.newMatch((EReference) t.get(POSITION_A));
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in tuple not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected OppositeDifferentClass.Match arrayToMatch(final Object[] match) {
+      try {
+          return OppositeDifferentClass.Match.newMatch((EReference) match[POSITION_A]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    @Override
+    protected OppositeDifferentClass.Match arrayToMatchMutable(final Object[] match) {
+      try {
+          return OppositeDifferentClass.Match.newMutableMatch((EReference) match[POSITION_A]);
+      } catch(ClassCastException e) {
+          LOGGER.error("Element(s) in array not properly typed!",e);
+          return null;
+      }
+    }
+    
+    /**
+     * @return the singleton instance of the query specification of this pattern
+     * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+     * 
+     */
+    public static IQuerySpecification<OppositeDifferentClass.Matcher> querySpecification() {
+      return OppositeDifferentClass.instance();
+    }
+  }
+  
+  private OppositeDifferentClass() {
+    super(GeneratedPQuery.INSTANCE);
+  }
+  
+  /**
+   * @return the singleton instance of the query specification
+   * @throws ViatraQueryRuntimeException if the pattern definition could not be loaded
+   * 
+   */
+  public static OppositeDifferentClass instance() {
+    try{
+        return LazyHolder.INSTANCE;
+    } catch (ExceptionInInitializerError err) {
+        throw processInitializerError(err);
+    }
+  }
+  
+  @Override
+  protected OppositeDifferentClass.Matcher instantiate(final ViatraQueryEngine engine) {
+    return OppositeDifferentClass.Matcher.on(engine);
+  }
+  
+  @Override
+  public OppositeDifferentClass.Matcher instantiate() {
+    return OppositeDifferentClass.Matcher.create();
+  }
+  
+  @Override
+  public OppositeDifferentClass.Match newEmptyMatch() {
+    return OppositeDifferentClass.Match.newEmptyMatch();
+  }
+  
+  @Override
+  public OppositeDifferentClass.Match newMatch(final Object... parameters) {
+    return OppositeDifferentClass.Match.newMatch((org.eclipse.emf.ecore.EReference) parameters[0]);
+  }
+  
+  /**
+   * Inner class allowing the singleton instance of {@link JvmGenericType: ecore.OppositeDifferentClass (visibility: PUBLIC, simpleName: OppositeDifferentClass, identifier: ecore.OppositeDifferentClass, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)} to be created 
+   *     <b>not</b> at the class load time of the outer class, 
+   *     but rather at the first call to {@link JvmGenericType: ecore.OppositeDifferentClass (visibility: PUBLIC, simpleName: OppositeDifferentClass, identifier: ecore.OppositeDifferentClass, deprecated: <unset>) (abstract: false, static: false, final: true, packageName: ecore) (interface: false, strictFloatingPoint: false, anonymous: false)#instance()}.
+   * 
+   * <p> This workaround is required e.g. to support recursion.
+   * 
+   */
+  private static class LazyHolder {
+    private static final OppositeDifferentClass INSTANCE = new OppositeDifferentClass();
+    
+    /**
+     * Statically initializes the query specification <b>after</b> the field {@link #INSTANCE} is assigned.
+     * This initialization order is required to support indirect recursion.
+     * 
+     * <p> The static initializer is defined using a helper field to work around limitations of the code generator.
+     * 
+     */
+    private static final Object STATIC_INITIALIZER = ensureInitialized();
+    
+    public static Object ensureInitialized() {
+      INSTANCE.ensureInitializedInternal();
+      return null;
+    }
+  }
+  
+  private static class GeneratedPQuery extends BaseGeneratedEMFPQuery {
+    private static final OppositeDifferentClass.GeneratedPQuery INSTANCE = new GeneratedPQuery();
+    
+    private final PParameter parameter_a = new PParameter("a", "org.eclipse.emf.ecore.EReference", new EClassTransitiveInstancesKey((EClass)getClassifierLiteralSafe("http://www.eclipse.org/emf/2002/Ecore", "EReference")), PParameterDirection.INOUT);
+    
+    private final List<PParameter> parameters = Arrays.asList(parameter_a);
+    
+    private GeneratedPQuery() {
+      super(PVisibility.PUBLIC);
+    }
+    
+    @Override
+    public String getFullyQualifiedName() {
+      return "ecore.oppositeDifferentClass";
+    }
+    
+    @Override
+    public List<String> getParameterNames() {
+      return Arrays.asList("a");
+    }
+    
+    @Override
+    public List<PParameter> getParameters() {
+      return parameters;
+    }
+    
+    @Override
+    public Set<PBody> doGetContainedBodies() {
+      setEvaluationHints(new QueryEvaluationHint(null, QueryEvaluationHint.BackendRequirement.UNSPECIFIED));
+      Set<PBody> bodies = new LinkedHashSet<>();
+      {
+          PBody body = new PBody(this);
+          PVariable var_a = body.getOrCreateVariableByName("a");
+          PVariable var_b = body.getOrCreateVariableByName("b");
+          PVariable var_aContaining = body.getOrCreateVariableByName("aContaining");
+          PVariable var_bTarget = body.getOrCreateVariableByName("bTarget");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          body.setSymbolicParameters(Arrays.<ExportedParameter>asList(
+             new ExportedParameter(body, var_a, parameter_a)
+          ));
+          //    EReference.eOpposite(a,b)
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          PVariable var__virtual_0_ = body.getOrCreateVariableByName(".virtual{0}");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a, var__virtual_0_), new EStructuralFeatureInstancesKey(getFeatureLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference", "eOpposite")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var__virtual_0_), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          new Equality(body, var__virtual_0_, var_b);
+          //    EReference.eContainingClass(a,aContaining)
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          PVariable var__virtual_1_ = body.getOrCreateVariableByName(".virtual{1}");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_a, var__virtual_1_), new EStructuralFeatureInstancesKey(getFeatureLiteral("http://www.eclipse.org/emf/2002/Ecore", "EStructuralFeature", "eContainingClass")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var__virtual_1_), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClass")));
+          new Equality(body, var__virtual_1_, var_aContaining);
+          //    EReference.eType(b,bTarget)
+          new TypeConstraint(body, Tuples.flatTupleOf(var_b), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EReference")));
+          PVariable var__virtual_2_ = body.getOrCreateVariableByName(".virtual{2}");
+          new TypeConstraint(body, Tuples.flatTupleOf(var_b, var__virtual_2_), new EStructuralFeatureInstancesKey(getFeatureLiteral("http://www.eclipse.org/emf/2002/Ecore", "ETypedElement", "eType")));
+          new TypeConstraint(body, Tuples.flatTupleOf(var__virtual_2_), new EClassTransitiveInstancesKey((EClass)getClassifierLiteral("http://www.eclipse.org/emf/2002/Ecore", "EClassifier")));
+          new Equality(body, var__virtual_2_, var_bTarget);
+          //    aContaining != bTarget
+          new Inequality(body, var_aContaining, var_bTarget);
+          bodies.add(body);
+      }
+      {
+          PAnnotation annotation = new PAnnotation("Constraint");
+          annotation.addAttribute("key", Arrays.asList(new Object[] {
+                              new ParameterReference("a")
+                              }));
+          annotation.addAttribute("severity", "error");
+          annotation.addAttribute("message", "error");
+          addAnnotation(annotation);
+      }
+      return bodies;
+    }
+  }
+}