Examples with TrailAssignment at.ac.tuwien.kr.alpha.core.solver.TrailAssignment used on opensource projects

Example 6 with TrailAssignment

use of at.ac.tuwien.kr.alpha.core.solver.TrailAssignment in project Alpha by alpha-asp.

the class NaiveGrounderTest method groundRuleWithLongerBodyAlreadyGround.

/**
 * Asserts that a ground rule whose positive non-unary body is not satisfied by the empty assignment
 * is grounded immediately.
 */
@Test
public void groundRuleWithLongerBodyAlreadyGround() {
    ASPCore2Program program = PROGRAM_PARSER.parse("a :- not b. " + "b :- not a. " + "c :- b. " + "d :- b, c. ");
    NormalProgram normal = NORMALIZE_TRANSFORM.apply(program);
    InternalProgram prog = new StratifiedEvaluation().apply(AnalyzedProgram.analyzeNormalProgram(normal));
    AtomStore atomStore = new AtomStoreImpl();
    Grounder grounder = GrounderFactory.getInstance("naive", prog, atomStore, true);
    Map<Integer, NoGood> noGoods = grounder.getNoGoods(new TrailAssignment(atomStore));
    int litANeg = Literals.atomToLiteral(atomStore.get(PROGRAM_PART_PARSER.parseBasicAtom("a")), false);
    int litBNeg = Literals.atomToLiteral(atomStore.get(PROGRAM_PART_PARSER.parseBasicAtom("b")), false);
    int litCNeg = Literals.atomToLiteral(atomStore.get(PROGRAM_PART_PARSER.parseBasicAtom("c")), false);
    int litDNeg = Literals.atomToLiteral(atomStore.get(PROGRAM_PART_PARSER.parseBasicAtom("d")), false);
    assertExistsNoGoodContaining(noGoods.values(), litANeg);
    assertExistsNoGoodContaining(noGoods.values(), litBNeg);
    assertExistsNoGoodContaining(noGoods.values(), litCNeg);
    assertExistsNoGoodContaining(noGoods.values(), litDNeg);
}

Example 7 with TrailAssignment

use of at.ac.tuwien.kr.alpha.core.solver.TrailAssignment in project Alpha by alpha-asp.

the class NaiveGrounderTest method testPermissiveGrounderHeuristicTolerance.

/**
 * Tests if {@link NaiveGrounder#getGroundInstantiations(InternalRule, RuleGroundingOrder, Substitution, Assignment)}
 * produces ground instantiations for the rule with ID {@code ruleID} in {@code program} when {@code startingLiteral}
 * unified with the numeric instance {@code startingInstance} is used as starting literal and the following
 * additional conditions are established:
 * <ul>
 * <li>The atoms {@code b([startingInstance], 1), ..., b([startingInstance], n)} are added to the grounder's
 * working memory without changing the assignment, where {@code arityOfB-1} occurences of {@code startingInstance}
 * are used instead of {@code [startingInstance]} and {@code n} is the length of the {@code truthsOfB} array.
 * For example, if the length of {@code truthsOfB} is 2 and {@code arityOfB} is also 2, these atoms are
 * {@code b(1,1), b(1,2)}.
 * </li>
 * <li>The same atoms are assigned the truth values in the {@code truthsOfB} array.</li>
 * </ul>
 * It is asserted that ground instantiations are produced if and only if {@code expectNoGoods} is true.
 * If ground instantiations are produced, it is also asserted that the numbers of unassigned positive body atoms
 * determined by {@code getGroundInstantiations} match those given in {@code expectedNumbersOfUnassignedPositiveBodyAtoms}.
 */
private void testPermissiveGrounderHeuristicTolerance(ASPCore2Program program, int ruleID, Literal startingLiteral, int startingInstance, int tolerance, ThriceTruth[] truthsOfB, int arityOfB, boolean expectNoGoods, List<Integer> expectedNumbersOfUnassignedPositiveBodyAtoms) {
    CompiledProgram internalPrg = InternalProgram.fromNormalProgram(NORMALIZE_TRANSFORM.apply(program));
    AtomStore atomStore = new AtomStoreImpl();
    TrailAssignment currentAssignment = new TrailAssignment(atomStore);
    GrounderHeuristicsConfiguration heuristicConfiguration = GrounderHeuristicsConfiguration.getInstance(tolerance, tolerance);
    NaiveGrounder grounder = (NaiveGrounder) GrounderFactory.getInstance("naive", internalPrg, atomStore, p -> true, heuristicConfiguration, true);
    int[] bAtomIDs = new int[truthsOfB.length];
    for (int i = 0; i < truthsOfB.length; i++) {
        int[] bTerms = new int[arityOfB];
        for (int n = 0; n < arityOfB; n++) {
            bTerms[n] = (n == arityOfB - 1) ? i + 1 : startingInstance;
        }
        bAtomIDs[i] = atomStore.putIfAbsent(atom("b", bTerms));
    }
    addAtomsToWorkingMemoryWithoutChangingTheAssignment(atomStore, grounder, bAtomIDs);
    assign(currentAssignment, bAtomIDs, truthsOfB);
    grounder.bootstrap();
    final CompiledRule nonGroundRule = grounder.getNonGroundRule(ruleID);
    final Substitution substStartingLiteral = BasicSubstitution.specializeSubstitution(startingLiteral, new Instance(Terms.newConstant(startingInstance)), BasicSubstitution.EMPTY_SUBSTITUTION);
    final BindingResult bindingResult = grounder.getGroundInstantiations(nonGroundRule, nonGroundRule.getGroundingInfo().orderStartingFrom(startingLiteral), substStartingLiteral, currentAssignment);
    assertEquals(expectNoGoods, bindingResult.size() > 0);
    if (bindingResult.size() > 0) {
        assertEquals(expectedNumbersOfUnassignedPositiveBodyAtoms, bindingResult.getNumbersOfUnassignedPositiveBodyAtoms());
    } else {
        assertTrue(bindingResult.getNumbersOfUnassignedPositiveBodyAtoms().isEmpty());
    }
}

Example 8 with TrailAssignment

use of at.ac.tuwien.kr.alpha.core.solver.TrailAssignment 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 9 with TrailAssignment

use of at.ac.tuwien.kr.alpha.core.solver.TrailAssignment 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 TrailAssignment

use of at.ac.tuwien.kr.alpha.core.solver.TrailAssignment in project Alpha by alpha-asp.

the class HeapOfActiveAtomsTest method setUp.

@BeforeEach
public void setUp() {
    atomStore = new AtomStoreImpl();
    assignment = new TrailAssignment(atomStore);
    noGoodStore = new NoGoodStoreAlphaRoaming(assignment);
    ChoiceManager choiceManager = new PseudoChoiceManager(assignment, noGoodStore);
    this.vsids = new VSIDS(assignment, choiceManager, MOMs.DEFAULT_STRATEGY);
}