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.constraints.cnf;
29
30 import static org.sat4j.core.LiteralsUtils.neg;
31 import org.sat4j.minisat.core.ILits;
32 import org.sat4j.specs.IVecInt;
33
34 public class LearntHTClause extends HTClause {
35
36 public LearntHTClause(IVecInt ps, ILits voc) {
37 super(ps, voc);
38 }
39
40 /**
41 *
42 */
43 private static final long serialVersionUID = 1L;
44
45 /*
46 * (non-Javadoc)
47 *
48 * @see org.sat4j.minisat.constraints.cnf.WLClause#register()
49 */
50 public void register() {
51 // looking for the literal to put in tail
52 if (middleLits.length > 0) {
53 int maxi = 0;
54 int maxlevel = voc.getLevel(middleLits[0]);
55 for (int i = 1; i < middleLits.length; i++) {
56 int level = voc.getLevel(middleLits[i]);
57 if (level > maxlevel) {
58 maxi = i;
59 maxlevel = level;
60 }
61 }
62 if (maxlevel > voc.getLevel(tail)) {
63 int l = tail;
64 tail = middleLits[maxi];
65 middleLits[maxi] = l;
66 }
67 }
68 // attach both head and tail literals.
69 voc.attach(neg(head), this);
70 voc.attach(neg(tail), this);
71
72 }
73
74 public boolean learnt() {
75 return true;
76 }
77
78 public void setLearnt() {
79 // do nothing
80 }
81
82 }