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

Example 1 with PBConstraint

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

the class FormulaStringRepresentation method toInnerString.

/**
 * Returns the string representation of the given formula.
 * <p>
 * This method is used for recursive calls in order to format the sub-formulas.
 * @param formula the formula
 * @return the string representation of the formula
 */
protected String toInnerString(final Formula formula) {
    switch(formula.type()) {
        case FALSE:
            return this.falsum();
        case TRUE:
            return this.verum();
        case LITERAL:
            final Literal lit = (Literal) formula;
            return lit.phase() ? lit.name() : this.negation() + lit.name();
        case NOT:
            final Not not = (Not) formula;
            return this.negation() + this.bracket(not.operand());
        case IMPL:
        case EQUIV:
            final BinaryOperator binary = (BinaryOperator) formula;
            String op = formula.type() == FType.IMPL ? this.implication() : this.equivalence();
            return this.binaryOperator(binary, op);
        case AND:
        case OR:
            final NAryOperator nary = (NAryOperator) formula;
            op = formula.type() == FType.AND ? this.and() : this.or();
            return this.naryOperator(nary, String.format("%s", op));
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            return String.format("%s%s%d", this.pbLhs(pbc.operands(), pbc.coefficients()), this.pbComparator(pbc.comparator()), pbc.rhs());
        default:
            throw new IllegalArgumentException("Cannot print the unknown formula type " + formula.type());
    }
}

Example 2 with PBConstraint

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

the class SortedStringRepresentation method toInnerString.

/**
 * Returns the sorted string representation of the given formula.
 * @param formula the formula
 * @return the sorted string representation of the formula with regard to the variable ordering
 */
@Override
public String toInnerString(final Formula formula) {
    switch(formula.type()) {
        case FALSE:
            return falsum();
        case TRUE:
            return verum();
        case LITERAL:
            final Literal lit = (Literal) formula;
            return lit.phase() ? lit.name() : negation() + lit.name();
        case NOT:
            final Not not = (Not) formula;
            return negation() + bracket(not.operand());
        case IMPL:
            return binaryOperator((BinaryOperator) formula, implication());
        case EQUIV:
            return sortedEquivalence((Equivalence) formula);
        case AND:
        case OR:
            final NAryOperator nary = (NAryOperator) formula;
            final String op = formula.type() == FType.AND ? and() : or();
            return naryOperator(nary, String.format("%s", op));
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            return String.format("%s%s%d", pbLhs(pbc.operands(), pbc.coefficients()), pbComparator(pbc.comparator()), pbc.rhs());
        default:
            throw new IllegalArgumentException("Cannot print the unknown formula type " + formula.type());
    }
}

Example 3 with PBConstraint

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

the class VariablesFunction method apply.

@Override
public SortedSet<Variable> apply(final Formula formula, final boolean cache) {
    final Object cached = formula.functionCacheEntry(VARIABLES);
    if (cached != null) {
        return (SortedSet<Variable>) cached;
    }
    SortedSet<Variable> result = new TreeSet<>();
    switch(formula.type()) {
        case FALSE:
        case TRUE:
            result = new TreeSet<>();
            break;
        case LITERAL:
            final Literal lit = (Literal) formula;
            result.add(lit.variable());
            break;
        case NOT:
            final Not not = (Not) formula;
            result = apply(not.operand(), cache);
            break;
        case IMPL:
        case EQUIV:
            final BinaryOperator binary = (BinaryOperator) formula;
            result.addAll(apply(binary.left(), cache));
            result.addAll(apply(binary.right(), cache));
            break;
        case OR:
        case AND:
            final NAryOperator nary = (NAryOperator) formula;
            for (final Formula op : nary) {
                result.addAll(apply(op, cache));
            }
            break;
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            result = FormulaHelper.variables(pbc.literals());
            break;
        default:
            throw new IllegalStateException("Unknown formula type " + formula.type());
    }
    result = Collections.unmodifiableSortedSet(result);
    if (cache) {
        formula.setFunctionCacheEntry(VARIABLES, result);
    }
    return result;
}

Example 4 with PBConstraint

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

the class DFSOrdering method dfs.

private void dfs(final Formula formula, final LinkedHashSet<Variable> variables) {
    switch(formula.type()) {
        case LITERAL:
            variables.add(((Literal) formula).variable());
            break;
        case NOT:
            dfs(((Not) formula).operand(), variables);
            break;
        case IMPL:
        case EQUIV:
            final BinaryOperator op = (BinaryOperator) formula;
            dfs(op.left(), variables);
            dfs(op.right(), variables);
            break;
        case AND:
        case OR:
            for (final Formula o : formula) {
                dfs(o, variables);
            }
            break;
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            for (final Literal lit : pbc.operands()) {
                variables.add(lit.variable());
            }
            break;
    }
}

Example 5 with PBConstraint

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

the class NNFTransformation method applyRec.

private Formula applyRec(final Formula formula, final boolean polarity) {
    final FormulaFactory f = formula.factory();
    Formula nnf;
    if (polarity) {
        nnf = formula.transformationCacheEntry(NNF);
        if (nnf != null) {
            return nnf;
        }
    }
    final FType type = formula.type();
    switch(type) {
        case TRUE:
        case FALSE:
        case LITERAL:
            nnf = polarity ? formula : formula.negate();
            break;
        case NOT:
            nnf = applyRec(((Not) formula).operand(), !polarity);
            break;
        case OR:
        case AND:
            nnf = applyRec(formula.iterator(), formula.type(), polarity, f);
            break;
        case EQUIV:
            final Equivalence equiv = (Equivalence) formula;
            if (polarity) {
                nnf = f.and(f.or(applyRec(equiv.left(), false), applyRec(equiv.right(), true)), f.or(applyRec(equiv.left(), true), applyRec(equiv.right(), false)));
            } else {
                nnf = f.and(f.or(applyRec(equiv.left(), false), applyRec(equiv.right(), false)), f.or(applyRec(equiv.left(), true), applyRec(equiv.right(), true)));
            }
            break;
        case IMPL:
            final Implication impl = (Implication) formula;
            if (polarity) {
                nnf = f.or(applyRec(impl.left(), false), applyRec(impl.right(), true));
            } else {
                nnf = f.and(applyRec(impl.left(), true), applyRec(impl.right(), false));
            }
            break;
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            if (polarity) {
                final List<Formula> encoding = pbc.getEncoding();
                nnf = applyRec(encoding.iterator(), FType.AND, true, f);
            } else {
                nnf = applyRec(pbc.negate(), true);
            }
            break;
        default:
            throw new IllegalStateException("Unknown formula type = " + type);
    }
    if (polarity) {
        formula.setTransformationCacheEntry(NNF, nnf);
    }
    return nnf;
}