Package net.sf.tweety.logics.pl.sat

Class MaxSatSolver

  • All Implemented Interfaces:
    net.sf.tweety.logics.commons.analysis.BeliefSetConsistencyTester<PlFormula>, net.sf.tweety.logics.commons.analysis.ConsistencyTester<net.sf.tweety.commons.BeliefSet<PlFormula,​?>>, net.sf.tweety.logics.commons.analysis.ConsistencyWitnessProvider<PlBeliefSet,​PlFormula>
    Direct Known Subclasses:
    OpenWboSolver
    public abstract class MaxSatSolver
extends SatSolver
    Provides a generic class for implementing MaxSAT solvers, i.e. solvers that get as input a set of hard constraints (=propositional formulas that need to be satisfied) and a set of soft constraints (=clauses with weights) whose satisfaction should be maximized (=sum of weights should be maximized).
    Author:
    Matthias Thimm

    • Constructor Detail

      • MaxSatSolver

        public MaxSatSolver()

    • Method Detail

      • setTempFolder

        public static void setTempFolder​(File tempFolder)
        Set the folder for temporary files created by a MaxSAT solver.
        Parameters:
        tempFolder - some temp folder.

      • getWitness

        public abstract net.sf.tweety.commons.Interpretation<PlBeliefSet,​PlFormula> getWitness​(Collection<PlFormula> hardConstraints,
                                                                                             Map<PlFormula,​Integer> softConstraints)
        Returns an interpretation with maximal weight on the soft constraints (or null if the hard constraints are not satisfiable)
        Parameters:
        hardConstraints - a set of propositional formulas
        softConstraints - a map mapping clauses to weights (if there is a formula, which is not a clause, i.e. a disjunction of literals), an exception is thrown.
        Returns:
        an interpretation with maximal weight on the soft constraints (or null if the hard constraints are not satisfiable)

      • getWitness

        public net.sf.tweety.commons.Interpretation<PlBeliefSet,​PlFormula> getWitness​(Collection<PlFormula> formulas)
        Description copied from class: SatSolver
        If the collection of formulas is consistent this method returns some model of it or, if it is inconsistent, null.
        Specified by:
        getWitness in interface net.sf.tweety.logics.commons.analysis.ConsistencyWitnessProvider<PlBeliefSet,​PlFormula>
        Specified by:
        getWitness in class SatSolver
        Returns:
        some model of the formulas or null.

      • isSatisfiable

        public boolean isSatisfiable​(Collection<PlFormula> formulas)
        Description copied from class: SatSolver
        Checks whether the given set of formulas is satisfiable.
        Specified by:
        isSatisfiable in class SatSolver
        Parameters:
        formulas - a set of formulas.
        Returns:
        "true" if the set is consistent.

      • convertToDimacsWcnf

        protected static String convertToDimacsWcnf​(Collection<PlFormula> hardConstraints,
                                            Map<PlFormula,​Integer> softConstraints,
                                            List<Proposition> props)
                                     throws IllegalArgumentException
        Converts the given MaxSAT instance (i.e. hard and soft constraints, the latter can only be clauses) to their string representation in Dimacs WCNF. Note that a single formula may be represented as multiple clauses, so there is no simple correspondence between the formulas of the set and the Dimacs representation.
        Parameters:
        hardConstraints - a collection of formulas
        softConstraints - a map mapping clauses to weights
        props - a list of propositions (=signature) where the indices are used for writing the clauses.
        Returns:
        a string in Dimacs CNF.
        Throws:
        IllegalArgumentException - if any soft constraint is not a clause.

      • createTmpDimacsWcnfFile

        protected static File createTmpDimacsWcnfFile​(Collection<PlFormula> hardConstraints,
                                              Map<PlFormula,​Integer> softConstraints,
                                              List<Proposition> props)
                                       throws IOException
        Converts the given MaxSAT instance (i.e. hard and soft constraints, the latter can only be clauses) to their string representation in Dimacs WCNF and writes it to a temporary file. Note that a single formula may be represented as multiple clauses, so there is no simple correspondence between the formulas of the set and the Dimacs representation.
        Parameters:
        hardConstraints - a collection of formulas
        softConstraints - a map mapping clauses to weights
        props - a list of propositions (=signature) where the indices are used for writing the clauses.
        Returns:
        a string in Dimacs CNF.
        Throws:
        IOException - if some file issue occurs
        IllegalArgumentException - if any soft constraint is not a clause.

      • costOf

        public static int costOf​(net.sf.tweety.commons.Interpretation<PlBeliefSet,​PlFormula> interpretation,
                         Collection<PlFormula> hardConstraints,
                         Map<PlFormula,​Integer> softConstraints)
        Returns the cost of the given interpretation, i.e. the sum of the weights of all violated soft constraints. If the interpretation does not satisfy the hard constraints -1 is returned;
        Parameters:
        interpretation - some interpretation
        hardConstraints - a set of hard constraints
        softConstraints - a set of soft constraints
        Returns:
        the cost of the interpretation