1 /******************************************************************************* 2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS 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 * Contributors: 28 * CRIL - initial API and implementation 29 *******************************************************************************/ 30 package org.sat4j.minisat.learning; 31 32 import org.sat4j.minisat.core.Constr; 33 import org.sat4j.minisat.core.DataStructureFactory; 34 import org.sat4j.minisat.core.ILits; 35 import org.sat4j.minisat.core.LearningStrategy; 36 import org.sat4j.minisat.core.Solver; 37 import org.sat4j.minisat.core.SolverStats; 38 import org.sat4j.minisat.core.VarActivityListener; 39 40 /** 41 * Learn only clauses which size is smaller than a percentage of the number of 42 * variables. 43 * 44 * @author leberre 45 */ 46 public abstract class LimitedLearning<D extends DataStructureFactory> 47 implements LearningStrategy<D> { 48 49 private static final long serialVersionUID = 1L; 50 51 private final NoLearningButHeuristics<D> none; 52 53 private final MiniSATLearning<D> all; 54 55 protected ILits lits; 56 57 private SolverStats stats; 58 59 public LimitedLearning() { 60 this.none = new NoLearningButHeuristics<D>(); 61 this.all = new MiniSATLearning<D>(); 62 } 63 64 public void setSolver(Solver<D> s) { 65 this.lits = s.getVocabulary(); 66 setVarActivityListener(s); 67 this.all.setDataStructureFactory(s.getDSFactory()); 68 this.stats = s.getStats(); 69 } 70 71 public void learns(Constr constr) { 72 if (learningCondition(constr)) { 73 this.all.learns(constr); 74 } else { 75 this.none.learns(constr); 76 this.stats.ignoredclauses++; 77 } 78 } 79 80 abstract protected boolean learningCondition(Constr constr); 81 82 public void init() { 83 this.all.init(); 84 this.none.init(); 85 } 86 87 public void setVarActivityListener(VarActivityListener s) { 88 this.none.setVarActivityListener(s); 89 this.all.setVarActivityListener(s); 90 } 91 }