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

Example 1 with NAryOperator

use of org.logicng.formulas.NAryOperator 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 NAryOperator

use of org.logicng.formulas.NAryOperator 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 NAryOperator

use of org.logicng.formulas.NAryOperator 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 NAryOperator

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

the class PureExpansionTransformation method apply.

@Override
public Formula apply(final Formula formula, final boolean cache) {
    final FormulaFactory f = formula.factory();
    switch(formula.type()) {
        case FALSE:
        case TRUE:
        case LITERAL:
            return formula;
        case NOT:
            final Not not = (Not) formula;
            return f.not(apply(not.operand(), cache));
        case OR:
        case AND:
            final NAryOperator nary = (NAryOperator) formula;
            final List<Formula> newOps = new ArrayList<>(nary.numberOfOperands());
            for (final Formula op : nary) {
                newOps.add(apply(op, cache));
            }
            return f.naryOperator(formula.type(), newOps);
        case IMPL:
        case EQUIV:
            final BinaryOperator binary = (BinaryOperator) formula;
            final Formula newLeft = apply(binary.left(), cache);
            final Formula newRight = apply(binary.right(), cache);
            return f.binaryOperator(formula.type(), newLeft, newRight);
        case PBC:
            final PBConstraint pbc = (PBConstraint) formula;
            if (pbc.isAmo() || pbc.isExo()) {
                final EncodingResult encodingResult = EncodingResult.resultForFormula(f);
                final Variable[] vars = literalsAsVariables(pbc.operands());
                this.amoEncoder.build(encodingResult, vars);
                final List<Formula> encoding = encodingResult.result();
                if (pbc.isExo()) {
                    encoding.add(f.or(vars));
                }
                return f.and(encoding);
            } else {
                throw new UnsupportedOperationException("Pure encoding for a PBC of type other than AMO or EXO is currently not supported.");
            }
        default:
            throw new IllegalStateException("Unknown formula type: " + formula.type());
    }
}

Example 5 with NAryOperator

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

the class FactorOutSimplifier method applyRec.

private Formula applyRec(final Formula formula, final boolean cache) {
    switch(formula.type()) {
        case OR:
        case AND:
            final List<Formula> newOps = new ArrayList<>();
            for (final Formula op : formula) {
                newOps.add(apply(op, cache));
            }
            final Formula newFormula = formula.factory().naryOperator(formula.type(), newOps);
            return newFormula instanceof NAryOperator ? simplify((NAryOperator) newFormula) : newFormula;
        case NOT:
            return apply(((Not) formula).operand(), cache).negate();
        case FALSE:
        case TRUE:
        case LITERAL:
        case IMPL:
        case EQUIV:
        case PBC:
            return formula;
        default:
            throw new IllegalStateException("Unknown formula type: " + formula.type());
    }
}