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.tools;
31
32 import org.sat4j.core.VecInt;
33 import org.sat4j.specs.ContradictionException;
34 import org.sat4j.specs.ISolver;
35 import org.sat4j.specs.IVecInt;
36 import org.sat4j.specs.TimeoutException;
37
38 /**
39 * Computes models with a minimal subset (with respect to set inclusion) of
40 * negative literals. This is done be adding a clause containing the negation of
41 * the negative literals appearing in the model found (which prevents any
42 * interpretation containing that subset of negative literals to be a model of
43 * the formula).
44 *
45 * Computes only one model minimal for inclusion, since there is currently no
46 * way to save the state of the solver.
47 *
48 * @author leberre
49 *
50 * @see org.sat4j.specs.ISolver#addClause(IVecInt)
51 */
52 public class Minimal4InclusionModel extends AbstractMinimalModel {
53
54 private static final long serialVersionUID = 1L;
55
56 private int[] prevfullmodel;
57
58 /**
59 *
60 * @param solver
61 * @param p
62 * the set of literals on which the minimality for inclusion is
63 * computed.
64 * @param modelListener
65 * an object to be notified when a new model is found.
66 */
67 public Minimal4InclusionModel(ISolver solver, IVecInt p,
68 SolutionFoundListener modelListener) {
69 super(solver, p, modelListener);
70 }
71
72 /**
73 *
74 * @param solver
75 * @param p
76 * the set of literals on which the minimality for inclusion is
77 * computed.
78 */
79 public Minimal4InclusionModel(ISolver solver, IVecInt p) {
80 this(solver, p, SolutionFoundListener.VOID);
81 }
82
83 /**
84 * @param solver
85 */
86 public Minimal4InclusionModel(ISolver solver) {
87 this(solver, negativeLiterals(solver), SolutionFoundListener.VOID);
88 }
89
90 /*
91 * (non-Javadoc)
92 *
93 * @see org.sat4j.ISolver#model()
94 */
95 @Override
96 public int[] model() {
97 int[] prevmodel = null;
98 IVecInt vec = new VecInt();
99 IVecInt cube = new VecInt();
100 try {
101 do {
102 prevfullmodel = super.modelWithInternalVariables();
103 prevmodel = super.model();
104 modelListener.onSolutionFound(prevmodel);
105 vec.clear();
106 cube.clear();
107 for (int q : prevfullmodel) {
108 if (pLiterals.contains(q)) {
109 vec.push(-q);
110 } else {
111 cube.push(q);
112 }
113 }
114 addBlockingClause(vec);
115 } while (isSatisfiable(cube));
116 } catch (TimeoutException e) {
117 throw new IllegalStateException("Solver timed out");
118 } catch (ContradictionException e) {
119 // added trivial unsat clauses
120 }
121
122 return prevmodel;
123
124 }
125
126 @Override
127 public int[] modelWithInternalVariables() {
128 model();
129 return prevfullmodel;
130 }
131 }