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