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 pseudo boolean algorithms described in:
20 * A fast pseudo-Boolean constraint solver Chai, D.; Kuehlmann, A.
21 * Computer-Aided Design of Integrated Circuits and Systems, IEEE Transactions on
22 * Volume 24, Issue 3, March 2005 Page(s): 305 - 317
23 *
24 * and
25 * Heidi E. Dixon, 2004. Automating Pseudo-Boolean Inference within a DPLL
26 * Framework. Ph.D. Dissertation, University of Oregon.
27 *******************************************************************************/
28 package org.sat4j.pb.constraints.pb;
29
30 import java.math.BigInteger;
31
32 public final class ConflictMapMerging extends ConflictMap {
33
34 public ConflictMapMerging(PBConstr cpb, int level) {
35 super(cpb, level);
36 }
37
38 public static IConflict createConflict(PBConstr cpb, int level) {
39 return new ConflictMapMerging(cpb, level);
40 }
41
42 /**
43 * reduces the constraint defined by wpb until the result of the cutting
44 * plane is a conflict. this reduction returns a PB constraint.
45 *
46 * @param litImplied
47 * @param ind
48 * @param reducedCoefs
49 * @param wpb
50 * @return the degree of the constraint
51 */
52 @Override
53 protected BigInteger reduceUntilConflict(int litImplied, int ind,
54 BigInteger[] reducedCoefs, WatchPb wpb) {
55 BigInteger tmp = reducedCoefs[ind].subtract(BigInteger.ONE);
56 reducedCoefs[ind] = BigInteger.ONE;
57 coefMultCons = weightedLits.get(litImplied ^ 1);
58 coefMult = BigInteger.ONE;
59 return saturation(reducedCoefs, wpb.getDegree().subtract(tmp));
60 }
61
62 }