modalLogic.tableau.WorldRelation.java Source code

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Here is the source code for modalLogic.tableau.WorldRelation.java

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/* Copyright (c) 2010, Johannes Kster <johannes.koester@tu-dortmund.de>
 * All rights reserved.
 *
 * This software is open-source under the BSD license; see "license.txt"
 * for a description.
 */

package modalLogic.tableau;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import org.apache.commons.collections15.MultiMap;
import org.apache.commons.collections15.multimap.MultiHashMap;
import util.Pair;

/**
 * Models a reachability relation between two worlds (see Kripke Models)
 * @author Johannes Kster <johannes.koester@tu-dortmund.de>
 */
public class WorldRelation<P> extends HashSet<Pair<World<P>>> {
    private MultiMap<LabelledFormula<P>, Pair<World<P>>> resulting = new MultiHashMap<LabelledFormula<P>, Pair<World<P>>>();

    /**
     * Returns the map between labelled formulas and resulting relations.
     *
     * @return the map
     */
    public MultiMap<LabelledFormula<P>, Pair<World<P>>> getResulting() {
        return resulting;
    }

    /**
     * Clear the relation.
     */
    @Override
    public void clear() {
        super.clear();
        resulting.clear();
    }

    /**
     * Add a relation between two worlds.
     *
     * @param w0 a world
     * @param w1 a world
     * @param reason the reason
     */
    public void add(World w0, World w1, LabelledFormula<P> reason) {
        Pair<World<P>> rel = new Pair<World<P>>(w0, w1);
        add(rel);
        /*Set<Pair<World<P>>> rs = resulting.get(reason);
        if(rs == null) {
          rs = new HashSet<Pair<World<P>>>();
          resulting.put(reason, rs);
        }
        rs.add(rel);*/

        resulting.put(reason, rel);
    }

    /**
     * Returns the reachable worlds for a given one.
     *
     * @param world the world
     * @return the reachable worlds
     */
    public Collection<World<P>> succ(World<P> world) {
        Collection<World<P>> succ = new ArrayList<World<P>>();

        for (Pair<World<P>> w : this) {
            if (w.getFirst().equals(world)) {
                succ.add(w.getSecond());
            }
        }
        return succ;
    }

    /**
     * Remove all relations caused by a given labelled formula.
     *
     * @param f the labelled formula
     */
    public void removeCausedBy(LabelledFormula<P> f) {
        Collection<Pair<World<P>>> res = resulting.get(f);
        if (res != null)
            removeAll(res);
        resulting.remove(f);
    }
}