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
33 /**
34 * A learning scheme for learning constraints of size smaller than a given
35 * constant.
36 *
37 * @author leberre
38 */
39 public class FixedLengthLearning<D extends DataStructureFactory> extends LimitedLearning<D> {
40
41 private static final long serialVersionUID = 1L;
42
43 private int maxlength;
44
45 private int bound;
46
47 public FixedLengthLearning() {
48 this(3);
49 }
50
51 public FixedLengthLearning(int maxlength) {
52 this.maxlength = maxlength;
53 }
54
55 /*
56 * (non-Javadoc)
57 *
58 * @see org.sat4j.minisat.LimitedLearning#learningCondition(org.sat4j.minisat.Constr)
59 */
60 @Override
61 public void init() {
62 setBound(maxlength);
63 }
64
65 public void setMaxLength(int v) {
66 maxlength = v;
67 }
68
69 public int getMaxLength() {
70 return maxlength;
71 }
72
73 @Override
74 public String toString() {
75 return "Limit learning to clauses of size smaller or equal to " //$NON-NLS-1$
76 + maxlength;
77 }
78
79 protected void setBound(int newbound) {
80 bound = newbound;
81 }
82
83 @Override
84 protected boolean learningCondition(Constr constr) {
85 return constr.size() <= bound;
86 }
87
88 }