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

Example 31 with Formula

use of org.logicng.formulas.Formula 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 32 with Formula

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

the class ForceOrdering method getOrder.

@Override
public List<Variable> getOrder(final Formula formula) {
    final SortedSet<Variable> originalVariables = new TreeSet<>(formula.variables());
    final Formula nnf = formula.nnf();
    originalVariables.addAll(nnf.variables());
    final Formula cnf = nnf.cnf();
    final Hypergraph<Variable> hypergraph = HypergraphGenerator.fromCNF(cnf);
    final Map<Variable, HypergraphNode<Variable>> nodes = new HashMap<>();
    for (final HypergraphNode<Variable> node : hypergraph.nodes()) {
        nodes.put(node.content(), node);
    }
    final List<Variable> ordering = force(cnf, hypergraph, nodes).stream().filter(originalVariables::contains).collect(Collectors.toList());
    originalVariables.stream().filter(v -> !ordering.contains(v)).forEach(ordering::add);
    return ordering;
}

Example 33 with Formula

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

the class FormulaDotFileWriter method generateNaryDotString.

private static void generateNaryDotString(final NAryOperator formula, final StringBuilder sb, final Map<Formula, Integer> ids, final String op) {
    for (final Formula operand : formula) {
        if (!ids.containsKey(operand)) {
            generateDotString(operand, sb, ids);
        }
    }
    final int id = ids.size();
    ids.put(formula, id);
    sb.append("  id").append(id).append(" [label=\"").append(op).append(String.format("\"];%n"));
    for (final Formula operand : formula) {
        sb.append("  id").append(id).append(" -> id").append(ids.get(operand)).append(String.format(";%n"));
    }
}

Example 34 with Formula

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

the class FormulaWriter method write.

/**
 * Writes a given formula to a file  with a given formula formatter.
 * @param file              the file
 * @param formula           the formula to write
 * @param splitAndMultiline indicates whether - if the formula is an conjunction - the single operands should be
 *                          written to different lines without a conjoining operator
 * @param formatter         the formatter for the formula
 * @throws IOException if there was a problem writing the file
 */
public static void write(final File file, final Formula formula, final boolean splitAndMultiline, final FormulaStringRepresentation formatter) throws IOException {
    final StringBuilder sb = new StringBuilder();
    if (splitAndMultiline && formula.type() == FType.AND) {
        for (final Formula f : formula) {
            sb.append(formatter.toString(f)).append(System.lineSeparator());
        }
    } else {
        sb.append(formatter.toString(formula));
    }
    try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8))) {
        writer.append(sb);
        writer.flush();
    }
}

Example 35 with Formula

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

the class BDDCNFFunction method apply.

@Override
public Formula apply(final BDD bdd) {
    final BDDKernel kernel = bdd.underlyingKernel();
    final List<byte[]> unsatPaths = new BDDOperations(kernel).allUnsat(bdd.index());
    final List<Formula> clauses = new ArrayList<>();
    List<Formula> literals;
    for (final byte[] path : unsatPaths) {
        literals = new ArrayList<>();
        for (int i = 0; i < path.length; i++) {
            if (path[i] == 0) {
                literals.add(kernel.getVariableForIndex(i));
            } else if (path[i] == 1) {
                literals.add(kernel.getVariableForIndex(i).negate());
            }
        }
        clauses.add(kernel.factory().or(literals));
    }
    return kernel.factory().and(clauses);
}