1 /*
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2006 Daniel Le Berre
3 *
4 * Based on the original minisat specification from:
5 *
6 * An extensible SAT solver. Niklas E?n and Niklas S?rensson. Proceedings of the
7 * Sixth International Conference on Theory and Applications of Satisfiability
8 * Testing, LNCS 2919, pp 502-518, 2003.
9 *
10 * This library is free software; you can redistribute it and/or modify it under
11 * the terms of the GNU Lesser General Public License as published by the Free
12 * Software Foundation; either version 2.1 of the License, or (at your option)
13 * any later version.
14 *
15 * This library is distributed in the hope that it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
18 * details.
19 *
20 * You should have received a copy of the GNU Lesser General Public License
21 * along with this library; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 */
25
26 package org.sat4j.minisat.uip;
27
28 import java.io.Serializable;
29
30 import org.sat4j.minisat.core.AssertingClauseGenerator;
31 import org.sat4j.specs.IConstr;
32
33 /**
34 * Decision UIP scheme for building an asserting clause. This is one of the
35 * simplest way to build an asserting clause: the generator stops when it meets
36 * a decision variable (a literal with no reason). Note that this scheme cannot
37 * be used for general constraints, since decision variables are not necessarily
38 * UIP in the pseudo boolean case.
39 *
40 * @author leberre
41 */
42 public class DecisionUIP implements AssertingClauseGenerator, Serializable {
43
44 private static final long serialVersionUID = 1L;
45
46 /*
47 * (non-Javadoc)
48 *
49 * @see org.sat4j.minisat.AnalysisScheme#initAnalyse()
50 */
51 public void initAnalyze() {
52 }
53
54 /*
55 * (non-Javadoc)
56 *
57 * @see org.sat4j.minisat.AnalysisScheme#onCurrentDecisionLevelLiteral()
58 */
59 public void onCurrentDecisionLevelLiteral(int p) {
60 }
61
62 /*
63 * (non-Javadoc)
64 *
65 * @see org.sat4j.minisat.AnalysisScheme#continueResolution(org.sat4j.datatype.Lit)
66 */
67 public boolean clauseNonAssertive(IConstr reason) {
68 return reason != null;
69 }
70
71 @Override
72 public String toString() {
73 return "Stops conflict analysis at the last decision variable";
74 }
75
76 }