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HermiT is reasoner for ontologies written using the Web Ontology Language (OWL). Given an OWL file, HermiT can determine whether or not the ontology is consistent, identify subsumption relationships between classes, and much more. This is the maven build of HermiT and is designed for people who wish to use HermiT from within the OWL API. It is now versioned in the main HermiT version repository, although not officially supported by the HermiT developers. The version number of this package is a composite of the HermiT version and an value representing releases of this packaged version. So, 1.3.7.1 is the first release of the mavenized version of HermiT based on the 1.3.7 release of HermiT. This package includes the Jautomata library (http://jautomata.sourceforge.net/), and builds with it directly. This library appears to be no longer under active development, and so a "fork" seems appropriate. No development is intended or anticipated on this code base.

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package rationals.transformations;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import rationals.Automaton;
import rationals.NoSuchStateException;
import rationals.State;
import rationals.Transition;

/**
 * Computes the minimal automaton from a deterministic automaton.
 * 
 * This class first determinizes the transformed automaton, then compute
 * states equivalence classes to create new states and transitions.
 * 
 * @author nono
 * @version $Id: Reducer.java 2 2006-08-24 14:41:48Z oqube $
 */
public class Reducer implements UnaryTransformation {

    /*
     * equivalence on DFA
     */
    private boolean same(State e1, State e2, Automaton a, Map m) {
        if (!m.get(e1).equals(m.get(e2)))
            return false;
        /* iterate over all transitions */
        Set tas = a.delta(e1);
        Set tbs = a.delta(e2);
        Iterator it = tas.iterator();
        while (it.hasNext()) {
            Transition tr = (Transition) it.next();
            State ep1 = tr.end();
            /* check transition exists in b */
            Set tbsl = a.delta(e2, tr.label());
            if (tbsl.isEmpty())
                return false;
            Iterator trb = tbsl.iterator();
            while (trb.hasNext()) {
                Transition tb = (Transition) trb.next();
                /* mark transition as visited */
                tbs.remove(tb);
                State ep2 = tb.end();
                if (!m.get(ep1).equals(m.get(ep2)))
                    return false;
            }
            
        }
        if (!tbs.isEmpty()) {
            return false;
        }
        return true;
    }

    public Automaton transform(Automaton a) {
        Automaton b = new ToDFA().transform(a);
        Map current = new HashMap();
        Set s1 = b.getStateFactory().stateSet();
        Set s2 = b.getStateFactory().stateSet();
        Iterator i = b.states().iterator();
        while (i.hasNext()) {
            State e = (State) i.next();
            if (e.isTerminal()) {
                s1.add(e);
                current.put(e, s1);
            } else {
                s2.add(e);
                current.put(e, s2);
            }
        }
        Map old;
        do {
            old = current;
            current = new HashMap();
            i = old.keySet().iterator();
            while (i.hasNext()) {
                State e1 = (State) i.next();
                Set s = b.getStateFactory().stateSet();
                Iterator j = current.keySet().iterator();
                while (j.hasNext()) {
                    State e2 = (State) j.next();
                    if (same(e1, e2, b, old)) {
                        s = (Set) current.get(e2);
                        break;
                    }
                }
                s.add(e1);
                current.put(e1, s);
            }
        } while (!new HashSet(current.values())
                .equals(new HashSet(old.values())));
        Automaton c = new Automaton();
        Set setSet = new HashSet(current.values());
        Iterator sets = setSet.iterator();
        Map newStates = new HashMap();
        while (sets.hasNext()) {
            Set set = (Set) sets.next();
            boolean term = TransformationsToolBox.containsATerminalState(set);
            boolean init = TransformationsToolBox.containsAnInitialState(set);
            newStates.put(set, c.addState(init, term));
        }
        sets = setSet.iterator();
        while (sets.hasNext()) {
            Set set = (Set) sets.next();
            State r = (State) set.iterator().next();
            State rp = (State) newStates.get(set);
            Iterator k = b.alphabet().iterator();
            while (k.hasNext()) {
                Object l = k.next();
                Set ds = b.delta(r, l);
                if(ds.isEmpty())
                    continue;
                State f = (State) ((Transition) ds.iterator().next())
                        .end();
                State fp = (State) newStates.get(current.get(f));
                try {
                    c.addTransition(new Transition(rp, l, fp));
                } catch (NoSuchStateException x) {
                }
            }
        }
        return c;
    }

}