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 * Selects the constraints to learn according to its length as a percentage of
35 * the total number of variables in the solver universe.
36 *
37 * @author daniel
38 *
39 */
40 public class PercentLengthLearning<D extends DataStructureFactory> extends LimitedLearning<D> {
41
42 /**
43 *
44 */
45 private static final long serialVersionUID = 1L;
46 private int maxpercent;
47 private int bound;
48
49 public PercentLengthLearning() {
50 this(10);
51 }
52
53 public PercentLengthLearning(int percent) {
54 maxpercent = percent;
55 }
56
57 public void setLimit(int percent) {
58 maxpercent = percent;
59 }
60
61 public int getLimit() {
62 return maxpercent;
63 }
64
65 @Override
66 public void init() {
67 super.init();
68 setBound(lits.realnVars() * maxpercent / 100);
69 }
70
71 @Override
72 public String toString() {
73 return "Limit learning to clauses of size smaller or equal to " //$NON-NLS-1$
74 + maxpercent + "% of the number of variables"; //$NON-NLS-1$
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 }