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 if (s != null) {
66 this.lits = s.getVocabulary();
67 setVarActivityListener(s);
68 this.all.setDataStructureFactory(s.getDSFactory());
69 this.stats = s.getStats();
70 }
71 }
72
73 public void learns(Constr constr) {
74 if (learningCondition(constr)) {
75 this.all.learns(constr);
76 } else {
77 this.none.learns(constr);
78 this.stats.ignoredclauses++;
79 }
80 }
81
82 protected abstract boolean learningCondition(Constr constr);
83
84 public void init() {
85 this.all.init();
86 this.none.init();
87 }
88
89 public void setVarActivityListener(VarActivityListener s) {
90 this.none.setVarActivityListener(s);
91 this.all.setVarActivityListener(s);
92 }
93 }