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