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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  }