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.minisat.restarts;
31
32 import org.sat4j.minisat.core.Constr;
33 import org.sat4j.minisat.core.RestartStrategy;
34 import org.sat4j.minisat.core.SearchParams;
35
36 /**
37 * Rapid restart strategy presented by Armin Biere during it's SAT 07 invited
38 * talk.
39 *
40 * @author leberre
41 *
42 */
43 public final class ArminRestarts implements RestartStrategy {
44
45 /**
46 *
47 */
48 private static final long serialVersionUID = 1L;
49
50 private double inner, outer;
51 private long conflicts;
52 private SearchParams params;
53 private long conflictcount = 0;
54
55 public void init(SearchParams theParams) {
56 this.params = theParams;
57 this.inner = theParams.getInitConflictBound();
58 this.outer = theParams.getInitConflictBound();
59 this.conflicts = Math.round(this.inner);
60 }
61
62 public long nextRestartNumberOfConflict() {
63 return this.conflicts;
64 }
65
66 public void onRestart() {
67 if (this.inner >= this.outer) {
68 this.outer *= this.params.getConflictBoundIncFactor();
69 this.inner = this.params.getInitConflictBound();
70 } else {
71 this.inner *= this.params.getConflictBoundIncFactor();
72 }
73 this.conflicts = Math.round(this.inner);
74 this.conflictcount = 0;
75 }
76
77 @Override
78 public String toString() {
79 return "Armin Biere (Picosat) restarts strategy";
80 }
81
82 public boolean shouldRestart() {
83 return this.conflictcount >= this.conflicts;
84 }
85
86 public void onBackjumpToRootLevel() {
87 this.conflictcount = 0;
88 }
89
90 public void reset() {
91 this.conflictcount = 0;
92 }
93
94 public void newConflict() {
95 this.conflictcount++;
96 }
97
98 public SearchParams getSearchParams() {
99 return this.params;
100 }
101
102 public void newLearnedClause(Constr learned, int trailLevel) {
103 }
104 }