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.opt;
31
32 import org.sat4j.core.VecInt;
33 import org.sat4j.specs.IOptimizationProblem;
34 import org.sat4j.specs.ISolver;
35 import org.sat4j.specs.IVecInt;
36 import org.sat4j.specs.TimeoutException;
37 import org.sat4j.tools.SolverDecorator;
38
39 /**
40 * Abstract class which adds a new "selector" variable for each clause entered
41 * in the solver.
42 *
43 * As a consequence, an original problem with n variables and m clauses will end
44 * up with n+m variables.
45 *
46 * @author daniel
47 *
48 */
49 public abstract class AbstractSelectorVariablesDecorator extends
50 SolverDecorator<ISolver> implements IOptimizationProblem {
51
52 /**
53 *
54 */
55 private static final long serialVersionUID = 1L;
56
57 private int nbexpectedclauses;
58
59 protected int[] prevfullmodel;
60
61 /**
62 * @since 2.1
63 */
64 protected int[] prevmodel;
65 /**
66 * @since 2.1
67 */
68 protected boolean[] prevboolmodel;
69
70 protected boolean isSolutionOptimal;
71
72 public AbstractSelectorVariablesDecorator(ISolver solver) {
73 super(solver);
74 }
75
76 @Override
77 public void setExpectedNumberOfClauses(int nb) {
78 this.nbexpectedclauses = nb;
79 }
80
81 public int getExpectedNumberOfClauses() {
82 return this.nbexpectedclauses;
83 }
84
85 public boolean admitABetterSolution() throws TimeoutException {
86 return admitABetterSolution(VecInt.EMPTY);
87 }
88
89 /**
90 * @since 2.1
91 */
92 public boolean admitABetterSolution(IVecInt assumps)
93 throws TimeoutException {
94 this.isSolutionOptimal = false;
95 boolean result = super.isSatisfiable(assumps, true);
96 if (result) {
97 this.prevboolmodel = new boolean[nVars()];
98 for (int i = 0; i < nVars(); i++) {
99 this.prevboolmodel[i] = decorated().model(i + 1);
100 }
101 this.prevfullmodel = super.modelWithInternalVariables();
102 this.prevmodel = super.model();
103 calculateObjectiveValue();
104 } else {
105 this.isSolutionOptimal = true;
106 }
107 return result;
108 }
109
110 abstract void calculateObjectiveValue();
111
112 @Override
113 public int[] model() {
114 return this.prevmodel;
115 }
116
117 @Override
118 public boolean model(int var) {
119 return this.prevboolmodel[var - 1];
120 }
121
122 public boolean isOptimal() {
123 return this.isSolutionOptimal;
124 }
125 }