1 /*
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2006 Daniel Le Berre
3 *
4 * Based on the original minisat specification from:
5 *
6 * An extensible SAT solver. Niklas E?n and Niklas S?rensson. Proceedings of the
7 * Sixth International Conference on Theory and Applications of Satisfiability
8 * Testing, LNCS 2919, pp 502-518, 2003.
9 *
10 * This library is free software; you can redistribute it and/or modify it under
11 * the terms of the GNU Lesser General Public License as published by the Free
12 * Software Foundation; either version 2.1 of the License, or (at your option)
13 * any later version.
14 *
15 * This library is distributed in the hope that it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
18 * details.
19 *
20 * You should have received a copy of the GNU Lesser General Public License
21 * along with this library; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 */
25
26 package org.sat4j.minisat.learning;
27
28 import org.sat4j.minisat.core.Constr;
29 import org.sat4j.minisat.core.ILits;
30 import org.sat4j.minisat.core.LearningStrategy;
31 import org.sat4j.minisat.core.Solver;
32 import org.sat4j.minisat.core.VarActivityListener;
33
34 /**
35 * Learn only clauses which size is smaller than a percentage of the number of
36 * variables.
37 *
38 * @author leberre
39 */
40 public abstract class LimitedLearning<L extends ILits> implements LearningStrategy<L> {
41
42 private static final long serialVersionUID = 1L;
43
44 private final NoLearningButHeuristics<L> none;
45
46 private final MiniSATLearning<L> all;
47
48 protected L lits;
49
50 public LimitedLearning() {
51 none = new NoLearningButHeuristics<L>();
52 all = new MiniSATLearning<L>();
53 }
54
55 public void setSolver(Solver<L> s) {
56 this.lits = s.getVocabulary();
57 setVarActivityListener(s);
58 all.setDataStructureFactory(s.getDSFactory());
59 }
60
61 public void learns(Constr constr) {
62 if (learningCondition(constr)) {
63 all.learns(constr);
64 } else {
65 none.learns(constr);
66 }
67 }
68
69 abstract protected boolean learningCondition(Constr constr);
70
71 public void init() {
72 all.init();
73 none.init();
74 }
75
76 public void setVarActivityListener(VarActivityListener s) {
77 none.setVarActivityListener(s);
78 all.setVarActivityListener(s);
79 }
80 }