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.uip;
29
30 import java.io.Serializable;
31
32 import org.sat4j.minisat.core.AssertingClauseGenerator;
33 import org.sat4j.specs.IConstr;
34
35 /**
36 * Decision UIP scheme for building an asserting clause. This is one of the
37 * simplest way to build an asserting clause: the generator stops when it meets
38 * a decision variable (a literal with no reason). Note that this scheme cannot
39 * be used for general constraints, since decision variables are not necessarily
40 * UIP in the pseudo boolean case.
41 *
42 * @author leberre
43 */
44 public class DecisionUIP implements AssertingClauseGenerator, Serializable {
45
46 private static final long serialVersionUID = 1L;
47
48 /*
49 * (non-Javadoc)
50 *
51 * @see org.sat4j.minisat.AnalysisScheme#initAnalyse()
52 */
53 public void initAnalyze() {
54 }
55
56 /*
57 * (non-Javadoc)
58 *
59 * @see org.sat4j.minisat.AnalysisScheme#onCurrentDecisionLevelLiteral()
60 */
61 public void onCurrentDecisionLevelLiteral(int p) {
62 }
63
64 /*
65 * (non-Javadoc)
66 *
67 * @see org.sat4j.minisat.AnalysisScheme#continueResolution(org.sat4j.datatype.Lit)
68 */
69 public boolean clauseNonAssertive(IConstr reason) {
70 return reason != null;
71 }
72
73 @Override
74 public String toString() {
75 return "Stops conflict analysis at the last decision variable";
76 }
77
78 }