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ELK consequence-based reasoning engine

There is a newer version: 0.4.3

/*
 * #%L
 * ELK Reasoner
 * 
 * $Id$
 * $HeadURL$
 * %%
 * Copyright (C) 2011 - 2012 Department of Computer Science, University of Oxford
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
package org.semanticweb.elk.reasoner.saturation.classes;

import org.semanticweb.elk.reasoner.indexing.hierarchy.IndexedClassExpression;
import org.semanticweb.elk.reasoner.indexing.hierarchy.IndexedPropertyChain;
import org.semanticweb.elk.reasoner.saturation.rulesystem.Context;
import org.semanticweb.elk.reasoner.saturation.rulesystem.RuleApplicationFactory;
import org.semanticweb.elk.util.collections.Multimap;

/**
 * The rule for propagating of inconsistencies ({@code owl:Nothing}) in
 * contexts
 * 
 * @author Frantisek Simancik
 * @author "Yevgeny Kazakov"
 * 
 * @param 
 *            the type of contexts that can be used with this inference rule
 */
public class RuleBottom implements
		InferenceRulePosSCE {

	public void apply(BackwardLink argument, C context,
			RuleApplicationFactory.Engine engine) {

		if (!context.isSatisfiable())
			engine.enqueue(argument.getTarget(),
					new PositiveSuperClassExpression(engine.getOwlNothing()));
	}

	@Override
	public void applySCE(PositiveSuperClassExpression argument, C context,
			RuleApplicationFactory.Engine engine) {

		IndexedClassExpression owlNothing = engine.getOwlNothing();
		if (argument.getExpression() != owlNothing)
			return;

		context.setSatisfiable(false);

		// propagate over all backward links
		final Multimap backLinks = context
				.getBackwardLinksByObjectProperty();

		if (backLinks != null) {
			for (IndexedPropertyChain relation : backLinks.keySet())
				for (Context target : backLinks.get(relation))
					engine.enqueue(target, new PositiveSuperClassExpression(
							owlNothing));
		}
	}

}