Examples with Substitution at.ac.tuwien.kr.alpha.api.grounder.Substitution used on opensource projects

Example 1 with Substitution

use of at.ac.tuwien.kr.alpha.api.grounder.Substitution in project Alpha by alpha-asp.

the class LiteralInstantiatorTest method workingMemoryBasedVerifyPositiveGroundLiteralSatisfied.

@Test
public void workingMemoryBasedVerifyPositiveGroundLiteralSatisfied() {
    Predicate p = Predicates.getPredicate("p", 2);
    WorkingMemory workingMemory = new WorkingMemory();
    workingMemory.initialize(p);
    workingMemory.addInstance(Atoms.newBasicAtom(p, Terms.newSymbolicConstant("x"), Terms.newSymbolicConstant("y")), true);
    VariableTerm x = Terms.newVariable("X");
    VariableTerm y = Terms.newVariable("Y");
    Literal lit = Literals.fromAtom(Atoms.newBasicAtom(p, x, y), true);
    Substitution substitution = new BasicSubstitution();
    substitution.put(x, Terms.newSymbolicConstant("x"));
    substitution.put(y, Terms.newSymbolicConstant("y"));
    LiteralInstantiator instantiator = new LiteralInstantiator(new WorkingMemoryBasedInstantiationStrategy(workingMemory));
    LiteralInstantiationResult result = instantiator.instantiateLiteral(lit, substitution);
    assertEquals(LiteralInstantiationResult.Type.CONTINUE, result.getType());
    List<ImmutablePair<Substitution, AssignmentStatus>> substitutions = result.getSubstitutions();
    assertEquals(1, substitutions.size());
    assertEquals(AssignmentStatus.TRUE, substitutions.get(0).right);
    Substitution resultSubstitution = substitutions.get(0).left;
    // With the given input substitution, lit is ground and satisfied -
    // we expect the instantiator to verify that.
    assertEquals(substitution, resultSubstitution);
}

Example 2 with Substitution

use of at.ac.tuwien.kr.alpha.api.grounder.Substitution in project Alpha by alpha-asp.

the class LiteralInstantiatorTest method workingMemoryBasedVerifyPositiveGroundLiteralUnsatisfied.

@Test
public void workingMemoryBasedVerifyPositiveGroundLiteralUnsatisfied() {
    Predicate p = Predicates.getPredicate("p", 2);
    WorkingMemory workingMemory = new WorkingMemory();
    workingMemory.initialize(p);
    VariableTerm x = Terms.newVariable("X");
    VariableTerm y = Terms.newVariable("Y");
    Literal lit = Literals.fromAtom(Atoms.newBasicAtom(p, x, y), true);
    Substitution substitution = new BasicSubstitution();
    substitution.put(x, Terms.newSymbolicConstant("x"));
    substitution.put(y, Terms.newSymbolicConstant("y"));
    LiteralInstantiator instantiator = new LiteralInstantiator(new WorkingMemoryBasedInstantiationStrategy(workingMemory));
    LiteralInstantiationResult result = instantiator.instantiateLiteral(lit, substitution);
    // With the given input substitution, lit is ground, but not satisfied -
    // we expect the instantiator to verify that and return an empty list of
    // substitutions.
    assertEquals(LiteralInstantiationResult.Type.STOP_BINDING, result.getType());
}

Example 3 with Substitution

use of at.ac.tuwien.kr.alpha.api.grounder.Substitution in project Alpha by alpha-asp.

the class LiteralInstantiatorTest method instantiateUnsatisfiedFixedInterpretationLiteral.

@Test
public void instantiateUnsatisfiedFixedInterpretationLiteral() {
    ComparisonAtom fiveEqualsThree = Atoms.newComparisonAtom(Terms.newVariable("FIVE"), Terms.newVariable("THREE"), ComparisonOperators.EQ);
    Literal lit = Literals.fromAtom(fiveEqualsThree, true);
    Substitution substitution = new BasicSubstitution();
    substitution.put(Terms.newVariable("FIVE"), Terms.newConstant(5));
    substitution.put(Terms.newVariable("THREE"), Terms.newConstant(3));
    LiteralInstantiator instantiator = new LiteralInstantiator(new WorkingMemoryBasedInstantiationStrategy(null));
    LiteralInstantiationResult result = instantiator.instantiateLiteral(lit, substitution);
    assertEquals(LiteralInstantiationResult.Type.STOP_BINDING, result.getType());
}

Example 4 with Substitution

use of at.ac.tuwien.kr.alpha.api.grounder.Substitution in project Alpha by alpha-asp.

the class LiteralInstantiatorTest method instantiateSatisfiedFixedInterpretationLiteral.

@Test
public void instantiateSatisfiedFixedInterpretationLiteral() {
    ComparisonAtom equalsThree = Atoms.newComparisonAtom(Terms.newConstant(3), Terms.newVariable("THREE"), ComparisonOperators.EQ);
    Literal lit = Literals.fromAtom(equalsThree, true);
    Substitution substitution = new BasicSubstitution();
    LiteralInstantiator instantiator = new LiteralInstantiator(new WorkingMemoryBasedInstantiationStrategy(null));
    LiteralInstantiationResult result = instantiator.instantiateLiteral(lit, substitution);
    assertEquals(LiteralInstantiationResult.Type.CONTINUE, result.getType());
    List<ImmutablePair<Substitution, AssignmentStatus>> resultSubstitutions = result.getSubstitutions();
    assertEquals(1, resultSubstitutions.size());
    assertEquals(AssignmentStatus.TRUE, resultSubstitutions.get(0).right);
    Substitution extendedSubstitution = resultSubstitutions.get(0).left;
    assertTrue(extendedSubstitution.isVariableSet(Terms.newVariable("THREE")));
    assertEquals(Terms.newConstant(3), extendedSubstitution.eval(Terms.newVariable("THREE")));
}

Example 5 with Substitution

use of at.ac.tuwien.kr.alpha.api.grounder.Substitution in project Alpha by alpha-asp.

the class StratifiedEvaluation method substituteFromRecentlyAddedInstances.

/**
 * Use this to find initial substitutions for a starting literal when grounding a rule.
 * In order to avoid finding the same ground instantiations of rules again, only look at
 * <code>modifiedInLastEvaluationRun</code> to obtain instances.
 *
 * @param lit the literal to substitute.
 * @return valid ground substitutions for the literal based on the recently added instances (i.e. instances derived in
 *         the last evaluation run).
 */
private List<Substitution> substituteFromRecentlyAddedInstances(Literal lit) {
    List<Substitution> retVal = new ArrayList<>();
    Set<Instance> instances = modifiedInLastEvaluationRun.get(lit.getPredicate());
    if (instances == null) {
        return Collections.emptyList();
    }
    for (Instance instance : instances) {
        Substitution unifyingSubstitution = BasicSubstitution.specializeSubstitution(lit, instance, BasicSubstitution.EMPTY_SUBSTITUTION);
        if (unifyingSubstitution != null) {
            retVal.add(unifyingSubstitution);
        }
    }
    return retVal;
}