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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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/* Copyright 2009 by the Oxford University Computing Laboratory

   This file is part of HermiT.

   HermiT is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   HermiT is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with HermiT.  If not, see .
*/
package org.semanticweb.HermiT.hierarchy;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Set;

public class HierarchySearch {
    public static  HierarchyNode findPosition(Relation hierarchyRelation,E element,HierarchyNode topNode,HierarchyNode bottomNode) {
        Set> parentNodes=findParents(hierarchyRelation,element,topNode);
        Set> childNodes=findChildren(hierarchyRelation,element,bottomNode,parentNodes);
        if (parentNodes.equals(childNodes)) {
            assert parentNodes.size()==1 && childNodes.size()==1;
            return parentNodes.iterator().next();
        }
        else {
            Set equivalentElements=new HashSet();
            equivalentElements.add(element);
            return new HierarchyNode(element,equivalentElements,parentNodes,childNodes);
        }
    }
    protected static  Set> findParents(final Relation hierarchyRelation,final E element,HierarchyNode topNode) {
        return search(
            new SearchPredicate>() {
                public Set> getSuccessorElements(HierarchyNode u) {
                    return u.m_childNodes;
                }
                public Set> getPredecessorElements(HierarchyNode u) {
                    return u.m_parentNodes;
                }
                public boolean trueOf(HierarchyNode u) {
                    return hierarchyRelation.doesSubsume(u.getRepresentative(),element);
                }
            },Collections.singleton(topNode),null);
    }
    protected static  Set> findChildren(final Relation hierarchyRelation,final E element,HierarchyNode bottomNode,Set> parentNodes) {
        if (parentNodes.size()==1 && hierarchyRelation.doesSubsume(element,parentNodes.iterator().next().getRepresentative()))
            return parentNodes;
        else {
            // We now determine the set of nodes that are descendants of each node in parentNodes
            Iterator> parentNodesIterator=parentNodes.iterator();
            Set> marked=new HashSet>(parentNodesIterator.next().getDescendantNodes());
            while (parentNodesIterator.hasNext()) {
                Set> freshlyMarked=new HashSet>();
                Set> visited=new HashSet>();
                Queue> toProcess=new LinkedList>();
                toProcess.add(parentNodesIterator.next());
                while (!toProcess.isEmpty()) {
                    HierarchyNode currentNode=toProcess.remove();
                    for (HierarchyNode childNode : currentNode.m_childNodes)
                        if (marked.contains(childNode))
                            freshlyMarked.add(childNode);
                        else if (visited.add(childNode))
                            toProcess.add(childNode);
                }
                toProcess.addAll(freshlyMarked);
                while (!toProcess.isEmpty()) {
                    HierarchyNode currentNode=toProcess.remove();
                    for (HierarchyNode childNode : currentNode.m_childNodes)
                        if (freshlyMarked.add(childNode))
                            toProcess.add(childNode);
                }
                marked=freshlyMarked;
            }
            // Determine the subset of marked that is directly above the bottomNode and that is below the current element.
            Set> aboveBottomNodes=new HashSet>();
            for (HierarchyNode node : marked)
                if (node.m_childNodes.contains(bottomNode) && hierarchyRelation.doesSubsume(element,node.getRepresentative()))
                    aboveBottomNodes.add(node);
            // If this set is empty, then we omit the bottom search phase.
            if (aboveBottomNodes.isEmpty()) {
                Set> childNodes=new HashSet>();
                childNodes.add(bottomNode);
                return childNodes;
            }
            else {
                return search(
                    new SearchPredicate>() {
                        public Set> getSuccessorElements(HierarchyNode u) {
                            return u.m_parentNodes;
                        }
                        public Set> getPredecessorElements(HierarchyNode u) {
                            return u.m_childNodes;
                        }
                        public boolean trueOf(HierarchyNode u) {
                            return hierarchyRelation.doesSubsume(element,u.getRepresentative());
                        }
                    },aboveBottomNodes,marked);
            }
        }
    }

    public static  Set search(SearchPredicate searchPredicate,Collection startSearch,Set possibilities) {
        SearchCache cache=new SearchCache(searchPredicate,possibilities);
        Set result=new HashSet();
        Set visited=new HashSet(startSearch);
        Queue toProcess=new LinkedList(startSearch);
        while (!toProcess.isEmpty()) {
            U current=toProcess.remove();
            boolean foundSubordinateElement=false;
            Set subordinateElements=searchPredicate.getSuccessorElements(current);
            for (U subordinateElement : subordinateElements)
                if (cache.trueOf(subordinateElement)) {
                    foundSubordinateElement=true;
                    if (visited.add(subordinateElement))
                        toProcess.add(subordinateElement);
                }
            if (!foundSubordinateElement)
                result.add(current);
        }
        return result;
    }

    public static interface Relation {
        boolean doesSubsume(U parent,U child);
    }

    public static interface SearchPredicate {
        Set getSuccessorElements(U u);
        Set getPredecessorElements(U u);
        boolean trueOf(U u);
    }

    protected static final class SearchCache {
        protected final SearchPredicate m_searchPredicate;
        protected final Set m_possibilities;
        protected final Set m_positives;
        protected final Set m_negatives;

        public SearchCache(SearchPredicate f,Set possibilities) {
            m_searchPredicate=f;
            m_possibilities=possibilities;
            m_positives=new HashSet();
            m_negatives=new HashSet();
        }
        public boolean trueOf(U element) {
            if (m_positives.contains(element))
                return true;
            else if (m_negatives.contains(element) || (m_possibilities!=null && !m_possibilities.contains(element)))
                return false;
            else {
                for (U superordinateElement : m_searchPredicate.getPredecessorElements(element)) {
                    if (!trueOf(superordinateElement)) {
                        m_negatives.add(element);
                        return false;
                    }
                }
                if (m_searchPredicate.trueOf(element)) {
                    m_positives.add(element);
                    return true;
                }
                else {
                    m_negatives.add(element);
                    return false;
                }
            }
        }
    }
}