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.core;
31
32 import org.sat4j.specs.IConstr;
33 import org.sat4j.specs.IVecInt;
34
35 /*
36 * Created on 16 oct. 2003
37 */
38
39 /**
40 * Basic constraint abstraction used in Solver.
41 *
42 * Any new constraint type should implement that interface.
43 *
44 * @author leberre
45 */
46 public interface Constr extends IConstr {
47
48 /**
49 * Remove a constraint from the solver.
50 *
51 * @param upl
52 * @since 2.1
53 */
54 void remove(UnitPropagationListener upl);
55
56 /**
57 * Simplifies a constraint, by removing top level falsified literals for
58 * instance.
59 *
60 * @return true iff the constraint is satisfied and can be removed from the
61 * database.
62 */
63 boolean simplify();
64
65 /**
66 * Compute the reason for a given assignment.
67 *
68 * If the constraint is a clause, it is supposed to be either a unit clause
69 * or a falsified one.
70 *
71 * @param p
72 * a satisfied literal (or Lit.UNDEFINED)
73 * @param outReason
74 * the list of falsified literals whose negation is the reason of
75 * the assignment of p to true.
76 */
77 void calcReason(int p, IVecInt outReason);
78
79 /**
80 * Increase the constraint activity.
81 *
82 * @param claInc
83 * the value to increase the activity with
84 */
85 void incActivity(double claInc);
86
87 /**
88 *
89 * @param claInc
90 * @since 2.1
91 *
92 */
93 @Deprecated
94 void forwardActivity(double claInc);
95
96 /**
97 * Indicate wether a constraint is responsible from an assignment.
98 *
99 * @return true if a constraint is a "reason" for an assignment.
100 */
101 boolean locked();
102
103 /**
104 * Mark a constraint as learnt.
105 */
106
107 void setLearnt();
108
109 /**
110 * Register the constraint to the solver.
111 */
112 void register();
113
114 /**
115 * Rescale the clause activity by a value.
116 *
117 * @param d
118 * the value to rescale the clause activity with.
119 */
120 void rescaleBy(double d);
121
122 /**
123 * Set the activity at a specific value
124 *
125 * @param d
126 * the new activity
127 * @since 2.3.1
128 */
129 void setActivity(double d);
130
131 /**
132 * Method called when the constraint is to be asserted. It means that the
133 * constraint was learned during the search and it should now propagate some
134 * truth values. In the clausal case, only one literal should be propagated.
135 * In other cases, it might be different.
136 *
137 * @param s
138 * a UnitPropagationListener to use for unit propagation.
139 */
140 void assertConstraint(UnitPropagationListener s);
141
142 }