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.orders;
29
30 import static org.sat4j.core.LiteralsUtils.neg;
31 import static org.sat4j.core.LiteralsUtils.var;
32
33 import java.math.BigInteger;
34
35 import org.sat4j.minisat.core.ILits;
36 import org.sat4j.minisat.core.IPhaseSelectionStrategy;
37 import org.sat4j.minisat.orders.PhaseInLastLearnedClauseSelectionStrategy;
38 import org.sat4j.minisat.orders.VarOrderHeap;
39 import org.sat4j.pb.ObjectiveFunction;
40 import org.sat4j.specs.IVec;
41 import org.sat4j.specs.IVecInt;
42
43 public class VarOrderHeapObjective extends VarOrderHeap<ILits> {
44
45 /**
46 *
47 */
48 private static final long serialVersionUID = 1L;
49
50 private ObjectiveFunction obj;
51
52 public VarOrderHeapObjective() {
53 this(new PhaseInLastLearnedClauseSelectionStrategy());
54 }
55
56 public VarOrderHeapObjective(IPhaseSelectionStrategy strategy) {
57 super(strategy);
58 }
59
60 public void setObjectiveFunction(ObjectiveFunction obj) {
61 this.obj = obj;
62 }
63
64 @Override
65 public void init() {
66 super.init();
67 if (obj != null) {
68 IVecInt vars = obj.getVars();
69 IVec<BigInteger> coefs = obj.getCoeffs();
70 for (int i = 0; i < vars.size(); i++) {
71 int dimacsLiteral = vars.get(i);
72 if (lits.belongsToPool(Math.abs(dimacsLiteral))) {
73 int p = lits.getFromPool(dimacsLiteral);
74 BigInteger c = coefs.get(i);
75 if (c.signum() < 0) {
76 p = neg(p);
77 }
78 int var = var(p);
79 activity[var] = c.abs().doubleValue();
80 if (heap.inHeap(var))
81 heap.increase(var);
82 else
83 heap.insert(var);
84 phaseStrategy.init(var, neg(p));
85 }
86 }
87 }
88 }
89
90 @Override
91 public String toString() {
92 return super.toString() + " taking into account the objective function";
93 }
94
95 }