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.opt;
29
30 import org.sat4j.core.VecInt;
31 import org.sat4j.specs.ContradictionException;
32 import org.sat4j.specs.IConstr;
33 import org.sat4j.specs.IOptimizationProblem;
34 import org.sat4j.specs.ISolver;
35 import org.sat4j.specs.IVecInt;
36
37 /**
38 * Computes a solution that satisfies the maximum of clauses.
39 *
40 * @author daniel
41 *
42 */
43 public class MaxSatDecorator extends AbstractSelectorVariablesDecorator
44 implements IOptimizationProblem {
45
46 /**
47 *
48 */
49 private static final long serialVersionUID = 1L;
50
51
52 public MaxSatDecorator(ISolver solver) {
53 super(solver);
54 }
55
56
57 @Override
58 public void setExpectedNumberOfClauses(int nb) {
59 super.setExpectedNumberOfClauses(nb);
60 lits.ensure(nb);
61 }
62
63
64 @Override
65 public IConstr addClause(IVecInt literals) throws ContradictionException {
66 int newvar = nborigvars + ++nbnewvar;
67 lits.push(newvar);
68 literals.push(newvar);
69 return super.addClause(literals);
70 }
71
72 @Override
73 public void reset() {
74 nbnewvar = 0;
75 lits.clear();
76 super.reset();
77 }
78
79 public boolean hasNoObjectiveFunction() {
80 return false;
81 }
82
83 public boolean nonOptimalMeansSatisfiable() {
84 return false;
85 }
86
87 public Number calculateObjective() {
88 counter = 0;
89 for (int q : prevfullmodel) {
90 if (q > nborigvars) {
91 counter++;
92 }
93 }
94 return counter;
95 }
96
97 private final IVecInt lits = new VecInt();
98
99 private int counter;
100
101 public void discard() throws ContradictionException {
102 super.addAtMost(lits, counter - 1);
103 }
104
105 }