Examples with Literal org.logicng.formulas.Literal used on opensource projects

Example 31 with Literal

use of org.logicng.formulas.Literal in project LogicNG by logic-ng.

the class UpZeroLiteralsFunction method apply.

@Override
public SortedSet<Literal> apply(final MiniSat solver, final Consumer<Tristate> resultSetter) {
    if (solver.getResult() == UNDEF) {
        throw new IllegalStateException("Cannot get unit propagated literals on level 0 as long as the formula is not solved.  Call 'sat' first.");
    }
    if (solver.getResult() == FALSE) {
        return null;
    }
    final LNGIntVector literals = solver.underlyingSolver().upZeroLiterals();
    final SortedSet<Literal> upZeroLiterals = new TreeSet<>();
    for (int i = 0; i < literals.size(); ++i) {
        final int lit = literals.get(i);
        upZeroLiterals.add(solver.factory().literal(solver.underlyingSolver().nameForIdx(MiniSatStyleSolver.var(lit)), !MiniSatStyleSolver.sign(lit)));
    }
    return upZeroLiterals;
}

Example 32 with Literal

use of org.logicng.formulas.Literal in project LogicNG by logic-ng.

the class Term method translateToFormula.

/**
 * Translates this term to a formula for a given variable ordering
 * @param varOrder the variable ordering
 * @return the translation of this term to a formula
 */
Formula translateToFormula(final List<Variable> varOrder) {
    final FormulaFactory f = varOrder.get(0).factory();
    assert this.bits.length == varOrder.size();
    final List<Literal> operands = new ArrayList<>(varOrder.size());
    for (int i = 0; i < this.bits.length; i++) {
        if (this.bits[i] != Tristate.UNDEF) {
            operands.add(this.bits[i] == Tristate.TRUE ? varOrder.get(i) : varOrder.get(i).negate());
        }
    }
    return f.and(operands);
}

Example 33 with Literal

use of org.logicng.formulas.Literal in project LogicNG by logic-ng.

the class AdvancedSimplifier method apply.

@Override
public Formula apply(final Formula formula, final boolean cache) {
    start(this.handler);
    final FormulaFactory f = formula.factory();
    final Backbone backbone = BackboneGeneration.compute(Collections.singletonList(formula), formula.variables(), BackboneType.POSITIVE_AND_NEGATIVE, satHandler(this.handler));
    if (backbone == null || aborted(this.handler)) {
        return null;
    }
    if (!backbone.isSat()) {
        return f.falsum();
    }
    final SortedSet<Literal> backboneLiterals = backbone.getCompleteBackbone();
    final Formula restrictedFormula = formula.restrict(new Assignment(backboneLiterals));
    final PrimeResult primeResult = PrimeCompiler.getWithMinimization().compute(restrictedFormula, PrimeResult.CoverageType.IMPLICANTS_COMPLETE, this.handler);
    if (primeResult == null || aborted(this.handler)) {
        return null;
    }
    final List<SortedSet<Literal>> primeImplicants = primeResult.getPrimeImplicants();
    final List<Formula> minimizedPIs = SmusComputation.computeSmusForFormulas(negateAllLiterals(primeImplicants, f), Collections.singletonList(restrictedFormula), f, this.handler);
    if (minimizedPIs == null || aborted(this.handler)) {
        return null;
    }
    final Formula minDnf = f.or(negateAllLiteralsInFormulas(minimizedPIs, f).stream().map(f::and).collect(Collectors.toList()));
    final Formula fullFactor = minDnf.transform(new FactorOutSimplifier(this.ratingFunction));
    return f.and(f.and(backboneLiterals), fullFactor).transform(new NegationSimplifier());
}

Example 34 with Literal

use of org.logicng.formulas.Literal in project LogicNG by logic-ng.

the class MiniSat method generateClauseVector.

/**
 * Generates a clause vector of a collection of literals.
 * @param literals the literals
 * @return the clause vector
 */
protected LNGIntVector generateClauseVector(final Collection<? extends Literal> literals) {
    final LNGIntVector clauseVec = new LNGIntVector(literals.size());
    for (final Literal lit : literals) {
        final int index = getOrAddIndex(lit);
        final int litNum = lit.phase() ? index * 2 : (index * 2) ^ 1;
        clauseVec.push(litNum);
    }
    return clauseVec;
}

Example 35 with Literal

use of org.logicng.formulas.Literal in project LogicNG by logic-ng.

the class PlaistedGreenbaumTransformation method pgVariable.

/**
 * Returns the auxiliary variable for a given formula.  Either the formula is already a variable, has already an
 * auxiliary variable or a new one is generated.
 * @param formula the formula
 * @return the old or new auxiliary variable
 */
private static Literal pgVariable(final Formula formula) {
    if (formula.type() == FType.LITERAL) {
        return (Literal) formula;
    }
    Literal var = (Literal) formula.transformationCacheEntry(PLAISTED_GREENBAUM_VARIABLE);
    if (var == null) {
        var = formula.factory().newCNFVariable();
        formula.setTransformationCacheEntry(PLAISTED_GREENBAUM_VARIABLE, var);
    }
    return var;
}