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 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 *******************************************************************************/ 28 package org.sat4j.minisat.core; 29 30 import java.io.Serializable; 31 32 /** 33 * The responsibility of that class is to choose the phase (positive or 34 * negative) of the variable that was selected by the IOrder. 35 * 36 * @author leberre 37 * 38 */ 39 public interface IPhaseSelectionStrategy extends Serializable { 40 41 /** 42 * To be called when the activity of a literal changed. 43 * 44 * @param p 45 * a literal. The associated variable will be updated. 46 */ 47 void updateVar(int p); 48 49 /** 50 * that method has the responsibility to initialize all arrays in the 51 * heuristics. 52 * 53 * @param nlength 54 * the number of variables managed by the heuristics. 55 */ 56 void init(int nlength); 57 58 /** 59 * initialize the phase of a given variable to the given value. That method 60 * is suppose to be called AFTER init(int). 61 * 62 * @param var 63 * a variable 64 * @param p 65 * it's initial phase 66 */ 67 void init(int var, int p); 68 69 /** 70 * indicate that a literal has been satisfied. 71 * 72 * @param p 73 */ 74 void assignLiteral(int p); 75 76 /** 77 * selects the phase of the variable according to a phase selection 78 * strategy. 79 * 80 * @param var 81 * a variable chosen by the heuristics 82 * @return either var or not var, depending of the selection strategy. 83 * 84 */ 85 int select(int var); 86 87 /** 88 * Allow to perform a specific action when a literal of the current decision 89 * level is updated. That method is called after {@link #updateVar(int)}. 90 * 91 * @param q 92 * a literal 93 */ 94 void updateVarAtDecisionLevel(int q); 95 }