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
31 /**
32 * A learning scheme for learning constraints of size smaller than a given
33 * constant.
34 *
35 * @author leberre
36 */
37 public class FixedLengthLearning<L extends ILits> extends LimitedLearning<L> {
38
39 private static final long serialVersionUID = 1L;
40
41 private int maxlength;
42
43 private int bound;
44
45 public FixedLengthLearning() {
46 this(3);
47 }
48
49 public FixedLengthLearning(int maxlength) {
50 this.maxlength = maxlength;
51 }
52
53 /*
54 * (non-Javadoc)
55 *
56 * @see org.sat4j.minisat.LimitedLearning#learningCondition(org.sat4j.minisat.Constr)
57 */
58 @Override
59 public void init() {
60 setBound(maxlength);
61 }
62
63 public void setMaxLength(int v) {
64 maxlength = v;
65 }
66
67 public int getMaxLength() {
68 return maxlength;
69 }
70
71 @Override
72 public String toString() {
73 return "Limit learning to clauses of size smaller or equal to " //$NON-NLS-1$
74 + maxlength;
75 }
76
77 protected void setBound(int newbound) {
78 bound = newbound;
79 }
80
81 @Override
82 protected boolean learningCondition(Constr constr) {
83 return constr.size() <= bound;
84 }
85
86 }