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.orders;
29
30 import static org.sat4j.core.LiteralsUtils.neg;
31 import static org.sat4j.core.LiteralsUtils.posLit;
32 import static org.sat4j.core.LiteralsUtils.var;
33
34 import java.util.ArrayList;
35 import java.util.Collections;
36 import java.util.List;
37
38 import org.sat4j.minisat.core.ILits23;
39
40 /**
41 * @author leberre Heuristique du prouveur. Changement par rapport au MiniSAT
42 * original : la gestion activity est faite ici et non plus dans Solver.
43 */
44 public class JWOrder extends VarOrder<ILits23> {
45
46 private static final long serialVersionUID = 1L;
47
48 private int computeWeight(int var) {
49 final int p = posLit(var);
50 int pos2 = lits.nBinaryClauses(p);
51 int neg2 = lits.nBinaryClauses(neg(p));
52 int pos3 = lits.nTernaryClauses(p);
53 int neg3 = lits.nTernaryClauses(neg(p));
54 long weight = (pos2 * neg2 * 100L + pos2 + neg2) * 5L + pos3 * neg3 * 10L
55 + pos3 + neg3;
56 assert weight <= Integer.MAX_VALUE;
57 if (weight == 0) {
58 int pos = lits.attaches(p).size();
59 int neg = lits.attaches(neg(p)).size();
60 weight = pos + neg;
61 }
62 return (int) weight;
63 }
64
65 /*
66 * (non-Javadoc)
67 *
68 * @see org.sat4j.minisat.IHeuristics#init()
69 */
70 @Override
71 public void init() {
72 super.init();
73 List<ValuedLit> v = new ArrayList<ValuedLit>(order.length);
74
75 for (int i = 1; i < order.length; i++) {
76 ValuedLit t = new ValuedLit(order[i],computeWeight(order[i]>> 1));
77 v.add(t);
78 }
79 Collections.sort(v);
80 // System.out.println(v);
81 for (int i = 0; i < v.size(); i++) {
82 ValuedLit t = v.get(i);
83 order[i + 1] = t.id;
84 int index = var(t.id);
85 varpos[index] = i + 1;
86 activity[index] = t.count;
87 }
88 lastVar = 1;
89
90 }
91
92 /*
93 * (non-Javadoc)
94 *
95 * @see org.sat4j.minisat.core.VarOrder#updateActivity(int)
96 */
97 @Override
98 protected void updateActivity(int var) {
99 activity[var] = computeWeight(var);
100 }
101
102 @Override
103 public String toString() {
104 return "Jeroslow-Wang static like heuristics updated when new clauses are learnt"; //$NON-NLS-1$
105 }
106 }