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.pb.constraints.pb;
31
32 import java.math.BigInteger;
33
34 public final class ConflictMapSwitchToClause extends ConflictMap {
35
36 public static int UpperBound;
37
38 public ConflictMapSwitchToClause(PBConstr cpb, int level) {
39 super(cpb, level);
40 }
41
42 public static IConflict createConflict(PBConstr cpb, int level) {
43 return new ConflictMapSwitchToClause(cpb, level);
44 }
45
46 /**
47 * reduces the constraint defined by wpb until the result of the cutting
48 * plane is a conflict. this reduction returns either a clause if .
49 *
50 * @param litImplied
51 * @param ind
52 * @param reducedCoefs
53 * @param wpb
54 * @return BigInteger.ONE
55 */
56 @Override
57 protected BigInteger reduceUntilConflict(int litImplied, int ind,
58 BigInteger[] reducedCoefs, IWatchPb wpb) {
59 BigInteger degreeCons = super.reduceUntilConflict(litImplied, ind,
60 reducedCoefs, wpb);
61 // updating of the degree of the conflict
62 int i = 0;
63 for (; i < reducedCoefs.length
64 && reducedCoefs[i].equals(BigInteger.ZERO) && i != ind; i++) {
65 }
66 if (i < reducedCoefs.length) {
67 BigInteger bigCoef = reducedCoefs[i].multiply(this.coefMultCons);
68 if (this.weightedLits.containsKey(wpb.get(i))) {
69 bigCoef = bigCoef.add(this.weightedLits.get(wpb.get(i))
70 .multiply(this.coefMult));
71 }
72 if (bigCoef.toString().length() > UpperBound) {
73 // if we deal with really big integers
74 // reducing the constraint to a clause
75 this.numberOfReductions++;
76 this.hasBeenReduced = true;
77 degreeCons = reduceToClause(ind, wpb, reducedCoefs);
78 this.coefMultCons = this.weightedLits.get(litImplied ^ 1);
79 this.coefMult = BigInteger.ONE;
80 }
81 }
82 return degreeCons;
83 }
84
85 private BigInteger reduceToClause(int ind, IWatchPb wpb,
86 BigInteger[] reducedCoefs) {
87 for (int i = 0; i < reducedCoefs.length; i++) {
88 if (i == ind || wpb.getVocabulary().isFalsified(wpb.get(i))) {
89 reducedCoefs[i] = BigInteger.ONE;
90 } else {
91 reducedCoefs[i] = BigInteger.ZERO;
92 }
93 }
94 return BigInteger.ONE;
95 }
96
97 }