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ELK consequence-based reasoning engine
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/*
 * #%L
 * elk-reasoner
 * 
 * $Id$
 * $HeadURL$
 * %%
 * Copyright (C) 2011 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.properties;

import java.util.Set;

import org.semanticweb.elk.reasoner.indexing.hierarchy.IndexedPropertyChain;
import org.semanticweb.elk.reasoner.stages.ObjectPropertyCompositionsPrecomputationStage;
import org.semanticweb.elk.reasoner.stages.ObjectPropertyHierarchyComputationStage;
import org.semanticweb.elk.util.collections.AbstractHashMultimap;
import org.semanticweb.elk.util.collections.ArrayHashSet;
import org.semanticweb.elk.util.collections.Multimap;

/**
 * 
 * This object is used for fast retrieval of property inclusions and
 * compositions which are needed during saturation of class expressions.
 * 
 * @author Frantisek Simancik
 * 
 */
public class SaturatedPropertyChain {
	protected final IndexedPropertyChain root;

	protected final Set derivedSubProperties;
	protected final Set derivedSuperProperties;

	protected AbstractHashMultimap compositionsByLeftSubProperty;
	protected AbstractHashMultimap compositionsByRightSubProperty;

	public SaturatedPropertyChain(IndexedPropertyChain iop) {
		this.root = iop;
		this.derivedSuperProperties = new ArrayHashSet();
		this.derivedSubProperties = new ArrayHashSet();
	}

	public IndexedPropertyChain getRoot() {
		return root;
	}

	/**
	 * @return All subproperties of the root property including root itself.
	 *         Computed in the {@link ObjectPropertyHierarchyComputationStage}.
	 */
	public Set getSubProperties() {
		return derivedSubProperties;
	}

	/**
	 * @return All superproperties of the root property including root itself.
	 *         Computed in the {@link ObjectPropertyHierarchyComputationStage}.
	 */
	public Set getSuperProperties() {
		return derivedSuperProperties;
	}

	/**
	 * @return A multimap from R to S such that ObjectPropertyChain(R, root)
	 *         implies S, null if empty. Computed in the
	 *         {@link ObjectPropertyCompositionsPrecomputationStage} which
	 *         already expands premises of complex property inclusions under
	 *         property hierarchies
	 */
	public Multimap getCompositionsByLeftSubProperty() {
		return compositionsByLeftSubProperty;
	}

	/**
	 * @return A multimap from R to S such that ObjectPropertyChain(root, R)
	 *         implies S, null if empty. Computed in the
	 *         {@link ObjectPropertyCompositionsPrecomputationStage} which
	 *         already expands premises of complex property inclusions under
	 *         property hierarchies
	 */
	public Multimap getCompositionsByRightSubProperty() {
		return compositionsByRightSubProperty;
	}

}