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.tools;
29
30 import org.sat4j.specs.ContradictionException;
31 import org.sat4j.specs.IOptimizationProblem;
32 import org.sat4j.specs.ISolver;
33 import org.sat4j.specs.IVecInt;
34 import org.sat4j.specs.TimeoutException;
35
36 public class OptToSatAdapter extends SolverDecorator<ISolver> {
37
38 /**
39 *
40 */
41 private static final long serialVersionUID = 1L;
42
43 IOptimizationProblem problem;
44
45 boolean modelComputed = false;
46
47 public OptToSatAdapter(IOptimizationProblem problem) {
48 super((ISolver) problem);
49 this.problem = problem;
50 }
51
52 @Override
53 public boolean isSatisfiable() throws TimeoutException {
54 modelComputed = false;
55 return problem.admitABetterSolution();
56 }
57
58 @Override
59 public boolean isSatisfiable(boolean global) throws TimeoutException {
60 throw new UnsupportedOperationException();
61 }
62
63 @Override
64 public boolean isSatisfiable(IVecInt assumps, boolean global)
65 throws TimeoutException {
66 throw new UnsupportedOperationException();
67 }
68
69 @Override
70 public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
71 throw new UnsupportedOperationException();
72 }
73
74 @Override
75 public int[] model() {
76 if (modelComputed)
77 return problem.model();
78
79 try {
80 assert problem.admitABetterSolution();
81 do {
82 problem.calculateObjective();
83 problem.discard();
84 } while (problem.admitABetterSolution());
85 } catch (TimeoutException e) {
86 // solver timeout
87 } catch (ContradictionException e) {
88 // OK, optimal model found
89 }
90 modelComputed = true;
91 return problem.model();
92 }
93
94 @Override
95 public boolean model(int var) {
96 if (!modelComputed)
97 model();
98 return problem.model(var);
99 }
100
101 @Override
102 public String toString(String prefix) {
103 return prefix+"Optimization to SAT adapter\n"+super.toString(prefix);
104 }
105 }