Examples with WorkingMemory at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory used on opensource projects

Example 6 with WorkingMemory

use of at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory in project Alpha by alpha-asp.

the class LiteralInstantiationStrategyTest method defaultLazyGroundingCheckUnassignedGroundLiteral.

/**
 * Uses {@link DefaultLazyGroundingInstantiationStrategy} to check the truth
 * (i.e. {@link AssignmentStatus}) of the positive ground literal "p(a)".
 *
 * In this case, the instantiation strategy has an empty assignment,
 * so we expect the instantiation strategy to determine that p(a) is UNASSIGNED.
 * Since UNASSIGNED and FALSE atoms are (potentially) stale in working memory,
 * we expect the atom "p(a)" to be added to the stale set by the instantiation
 * strategy.
 */
@Test
public void defaultLazyGroundingCheckUnassignedGroundLiteral() {
    Predicate p = Predicates.getPredicate("p", 1);
    BasicAtom pOfA = Atoms.newBasicAtom(p, Terms.newSymbolicConstant("a"));
    WorkingMemory workingMemory = new WorkingMemory();
    AtomStore atomStore = new AtomStoreImpl();
    WritableAssignment assignment = new TrailAssignment(atomStore);
    LinkedHashSet<Atom> staleSet = new LinkedHashSet<>();
    DefaultLazyGroundingInstantiationStrategy strategy = new DefaultLazyGroundingInstantiationStrategy(workingMemory, atomStore, Collections.emptyMap(), false);
    strategy.setStaleWorkingMemoryEntries(staleSet);
    strategy.setCurrentAssignment(assignment);
    AssignmentStatus assignmentStatus = strategy.getTruthForGroundLiteral(Literals.fromAtom(pOfA, true));
    assertEquals(AssignmentStatus.UNASSIGNED, assignmentStatus);
    assertEquals(1, staleSet.size());
    assertTrue(staleSet.contains(pOfA));
}

Example 7 with WorkingMemory

use of at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory in project Alpha by alpha-asp.

the class LiteralInstantiationStrategyTest method defaultLazyGroundingCheckFalseGroundLiteral.

/**
 * Uses {@link DefaultLazyGroundingInstantiationStrategy} to check the truth
 * (i.e. {@link AssignmentStatus}) of the positive ground literal "p(a)".
 *
 * In this case, the instantiation strategy has an assignment where the atom
 * "p(a)" is assigned ThriceTruth.FALSE, so we expect the instantiation strategy
 * to determine that p(a) is FALSE. Since UNASSIGNED and FALSE atoms are
 * (potentially) stale in working memory, we expect the atom "p(a)" to be added
 * to the stale set by the instantiation strategy.
 */
@Test
public void defaultLazyGroundingCheckFalseGroundLiteral() {
    Predicate p = Predicates.getPredicate("p", 1);
    BasicAtom pOfA = Atoms.newBasicAtom(p, Terms.newSymbolicConstant("a"));
    WorkingMemory workingMemory = new WorkingMemory();
    AtomStore atomStore = new AtomStoreImpl();
    WritableAssignment assignment = new TrailAssignment(atomStore);
    atomStore.putIfAbsent(pOfA);
    assignment.growForMaxAtomId();
    assignment.assign(atomStore.get(pOfA), ThriceTruth.FALSE);
    LinkedHashSet<Atom> staleSet = new LinkedHashSet<>();
    DefaultLazyGroundingInstantiationStrategy strategy = new DefaultLazyGroundingInstantiationStrategy(workingMemory, atomStore, Collections.emptyMap(), false);
    strategy.setStaleWorkingMemoryEntries(staleSet);
    strategy.setCurrentAssignment(assignment);
    AssignmentStatus assignmentStatus = strategy.getTruthForGroundLiteral(Literals.fromAtom(pOfA, true));
    assertEquals(AssignmentStatus.FALSE, assignmentStatus);
    assertEquals(1, staleSet.size());
    assertTrue(staleSet.contains(pOfA));
}

Example 8 with WorkingMemory

use of at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory in project Alpha by alpha-asp.

the class LiteralInstantiationStrategyTest method defaultLazyGroundingNoAssignmentSubstituteNonGroundLiteral.

/**
 * Uses {@link DefaultLazyGroundingInstantiationStrategy} to find ground
 * instances for the partially ground positive literal "q(a, X)".
 *
 * In this case, the instantiation strategy does not have an assignment set (as
 * is the case when {@link NaiveGrounder} is in bootstrap), so we expect the
 * assignment status (i.e. assignment status of the found ground instance)
 * passed back with the substitution to be TRUE. Furthermore, the stale atom set
 * (used by {@link NaiveGrounder} to clean up atoms that should be deleted from
 * working memory) must stay empty.
 */
@Test
public void defaultLazyGroundingNoAssignmentSubstituteNonGroundLiteral() {
    Predicate q = Predicates.getPredicate("q", 2);
    BasicAtom nonGroundAtom = Atoms.newBasicAtom(q, Terms.newSymbolicConstant("a"), Terms.newVariable("X"));
    WorkingMemory workingMemory = new WorkingMemory();
    workingMemory.initialize(q);
    workingMemory.addInstance(Atoms.newBasicAtom(q, Terms.newSymbolicConstant("a"), Terms.newSymbolicConstant("b")), true);
    LinkedHashSet<Atom> staleSet = new LinkedHashSet<>();
    DefaultLazyGroundingInstantiationStrategy strategy = new DefaultLazyGroundingInstantiationStrategy(workingMemory, new AtomStoreImpl(), Collections.emptyMap(), false);
    strategy.setStaleWorkingMemoryEntries(staleSet);
    strategy.setCurrentAssignment(null);
    List<ImmutablePair<Substitution, AssignmentStatus>> result = strategy.getAcceptedSubstitutions(Literals.fromAtom(nonGroundAtom, true), new BasicSubstitution());
    assertEquals(1, result.size());
    ImmutablePair<Substitution, AssignmentStatus> substitutionInfo = result.get(0);
    Substitution substitution = substitutionInfo.left;
    AssignmentStatus assignmentStatus = substitutionInfo.right;
    assertEquals(AssignmentStatus.TRUE, assignmentStatus);
    assertTrue(substitution.isVariableSet(Terms.newVariable("X")));
    assertEquals(Terms.newSymbolicConstant("b"), substitution.eval(Terms.newVariable("X")));
    assertTrue(staleSet.isEmpty());
}

Example 9 with WorkingMemory

use of at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory in project Alpha by alpha-asp.

the class LiteralInstantiationStrategyTest method defaultLazyGroundingSubstituteNonGroundLiteralWithFalseInstance.

/**
 * Uses {@link DefaultLazyGroundingInstantiationStrategy} to find the ground
 * instance "q(a, b)" for the partially ground positive literal "q(a, X)".
 *
 * In this case, the instantiation strategy has an assignment where q(a, b) is
 * assigned ThriceTruth.FALSE, so we expect an empty list from
 * {@link LiteralInstantiationStrategy#getAcceptedSubstitutions(Literal, Substitution)}.
 * Furthermore, we expect the atom q(a, b) to be added to the stale atom set.
 */
@Test
public void defaultLazyGroundingSubstituteNonGroundLiteralWithFalseInstance() {
    Predicate q = Predicates.getPredicate("q", 2);
    BasicAtom nonGroundAtom = Atoms.newBasicAtom(q, Terms.newSymbolicConstant("a"), Terms.newVariable("X"));
    WorkingMemory workingMemory = new WorkingMemory();
    workingMemory.initialize(q);
    workingMemory.addInstance(Atoms.newBasicAtom(q, Terms.newSymbolicConstant("a"), Terms.newSymbolicConstant("b")), true);
    AtomStore atomStore = new AtomStoreImpl();
    WritableAssignment assignment = new TrailAssignment(atomStore);
    BasicAtom groundAtom = Atoms.newBasicAtom(q, Terms.newSymbolicConstant("a"), Terms.newSymbolicConstant("b"));
    atomStore.putIfAbsent(groundAtom);
    assignment.growForMaxAtomId();
    assignment.assign(atomStore.get(groundAtom), ThriceTruth.FALSE);
    LinkedHashSet<Atom> staleSet = new LinkedHashSet<>();
    DefaultLazyGroundingInstantiationStrategy strategy = new DefaultLazyGroundingInstantiationStrategy(workingMemory, atomStore, Collections.emptyMap(), false);
    strategy.setStaleWorkingMemoryEntries(staleSet);
    strategy.setCurrentAssignment(assignment);
    List<ImmutablePair<Substitution, AssignmentStatus>> result = strategy.getAcceptedSubstitutions(Literals.fromAtom(nonGroundAtom, true), new BasicSubstitution());
    assertTrue(result.isEmpty());
    assertEquals(1, staleSet.size());
    assertTrue(staleSet.contains(groundAtom));
}

Example 10 with WorkingMemory

use of at.ac.tuwien.kr.alpha.core.grounder.WorkingMemory in project Alpha by alpha-asp.

the class LiteralInstantiatorTest method workingMemoryBasedInstantiatePositiveBasicLiteral.

@Test
public void workingMemoryBasedInstantiatePositiveBasicLiteral() {
    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);
    workingMemory.addInstance(Atoms.newBasicAtom(p, Terms.newSymbolicConstant("x"), Terms.newSymbolicConstant("z")), 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"));
    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(2, substitutions.size());
    boolean ySubstituted = false;
    boolean zSubstituted = false;
    for (ImmutablePair<Substitution, AssignmentStatus> resultSubstitution : substitutions) {
        assertTrue(resultSubstitution.left.isVariableSet(y));
        assertEquals(AssignmentStatus.TRUE, resultSubstitution.right);
        if (resultSubstitution.left.eval(y).equals(Terms.newSymbolicConstant("y"))) {
            ySubstituted = true;
        } else if (resultSubstitution.left.eval(y).equals(Terms.newSymbolicConstant("z"))) {
            zSubstituted = true;
        } else {
            fail("Invalid substitution for variable Y");
        }
    }
    assertTrue(ySubstituted && zSubstituted);
}