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1   /*******************************************************************************
2    * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
3    *
4    * All rights reserved. This program and the accompanying materials
5    * are made available under the terms of the Eclipse Public License v1.0
6    * which accompanies this distribution, and is available at
7    * http://www.eclipse.org/legal/epl-v10.html
8    *
9    * Alternatively, the contents of this file may be used under the terms of
10   * either the GNU Lesser General Public License Version 2.1 or later (the
11   * "LGPL"), in which case the provisions of the LGPL are applicable instead
12   * of those above. If you wish to allow use of your version of this file only
13   * under the terms of the LGPL, and not to allow others to use your version of
14   * this file under the terms of the EPL, indicate your decision by deleting
15   * the provisions above and replace them with the notice and other provisions
16   * required by the LGPL. If you do not delete the provisions above, a recipient
17   * may use your version of this file under the terms of the EPL or the LGPL.
18   * 
19   * Based on the original MiniSat specification from:
20   * 
21   * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
22   * Sixth International Conference on Theory and Applications of Satisfiability
23   * Testing, LNCS 2919, pp 502-518, 2003.
24   *
25   * See www.minisat.se for the original solver in C++.
26   * 
27   *******************************************************************************/
28  package org.sat4j.minisat.learning;
29  
30  import org.sat4j.minisat.constraints.cnf.WLClause;
31  import org.sat4j.minisat.core.Constr;
32  import org.sat4j.minisat.core.DataStructureFactory;
33  
34  /**
35   * The solver only records among all the constraints only the clauses.
36   * 
37   * @author daniel
38   * 
39   * @param <L>
40   *            a data structure for the literals.
41   * @param <D>
42   *            a data structure for the clauses.
43   */
44  public final class ClauseOnlyLearning<D extends DataStructureFactory> extends
45  		LimitedLearning<D> {
46  
47  	/**
48       * 
49       */
50  	private static final long serialVersionUID = 1L;
51  
52  	@Override
53  	protected boolean learningCondition(Constr constr) {
54  		return constr instanceof WLClause;
55  	}
56  
57  	@Override
58  	public String toString() {
59  		return "Limit learning to clauses using watched literals only";
60  	}
61  }