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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  import org.sat4j.minisat.core.SolverStats;
36  
37  /**
38   * Minisat original restart strategy.
39   * 
40   * @author leberre
41   * 
42   */
43  public final class MiniSATRestarts implements RestartStrategy {
44  
45      /**
46       * 
47       */
48      private static final long serialVersionUID = 1L;
49  
50      private double nofConflicts;
51  
52      private SearchParams params;
53  
54      private int conflictcount;
55  
56      public void init(SearchParams theParams, SolverStats stats) {
57          this.params = theParams;
58          this.nofConflicts = theParams.getInitConflictBound();
59          this.conflictcount = 0;
60      }
61  
62      public long nextRestartNumberOfConflict() {
63          return Math.round(this.nofConflicts);
64      }
65  
66      public void onRestart() {
67          this.nofConflicts *= this.params.getConflictBoundIncFactor();
68      }
69  
70      @Override
71      public String toString() {
72          return "MiniSAT restarts strategy";
73      }
74  
75      public boolean shouldRestart() {
76          return this.conflictcount >= this.nofConflicts;
77      }
78  
79      public void onBackjumpToRootLevel() {
80          this.conflictcount = 0;
81      }
82  
83      public void reset() {
84          this.conflictcount = 0;
85      }
86  
87      public void newConflict() {
88          this.conflictcount++;
89      }
90  
91      public void newLearnedClause(Constr learned, int trailLevel) {
92      }
93  }