1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
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 * Contributors:
28 * CRIL - initial API and implementation
29 *******************************************************************************/
30 package org.sat4j.minisat.learning;
31
32 import org.sat4j.minisat.core.Constr;
33 import org.sat4j.minisat.core.DataStructureFactory;
34
35 /**
36 * Selects the constraints to learn according to its length as a percentage of
37 * the total number of variables in the solver universe.
38 *
39 * @author daniel
40 *
41 */
42 public final class PercentLengthLearning<D extends DataStructureFactory>
43 extends LimitedLearning<D> {
44
45 /**
46 *
47 */
48 private static final long serialVersionUID = 1L;
49 private int maxpercent;
50 private int bound;
51
52 public PercentLengthLearning() {
53 this(10);
54 }
55
56 public PercentLengthLearning(int percent) {
57 this.maxpercent = percent;
58 }
59
60 public void setLimit(int percent) {
61 this.maxpercent = percent;
62 }
63
64 public int getLimit() {
65 return this.maxpercent;
66 }
67
68 @Override
69 public void init() {
70 super.init();
71 setBound(this.lits.realnVars() * this.maxpercent / 100);
72 }
73
74 @Override
75 public String toString() {
76 return "Limit learning to clauses of size smaller or equal to " //$NON-NLS-1$
77 + this.maxpercent + "% of the number of variables"; //$NON-NLS-1$
78 }
79
80 protected void setBound(int newbound) {
81 this.bound = newbound;
82 }
83
84 @Override
85 protected boolean learningCondition(Constr constr) {
86 return constr.size() <= this.bound;
87 }
88
89 }