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 and can be removed from the
59 * database.
60 */
61 boolean simplify();
62
63 /**
64 * Compute the reason for a given assignment.
65 *
66 * If the constraint is a clause, it is supposed to be either a unit clause
67 * or a falsified one.
68 *
69 * @param p
70 * a satisfied literal (or Lit.UNDEFINED)
71 * @param outReason
72 * the list of falsified literals whose negation is the reason of
73 * the assignment of p to true.
74 */
75 void calcReason(int p, IVecInt outReason);
76
77 /**
78 * Increase the constraint activity.
79 *
80 * @param claInc
81 * the value to increase the activity with
82 */
83 void incActivity(double claInc);
84
85 /**
86 *
87 * @param claInc
88 * @since 2.1
89 *
90 */
91 @Deprecated
92 void forwardActivity(double claInc);
93
94 /**
95 * Indicate wether a constraint is responsible from an assignment.
96 *
97 * @return true if a constraint is a "reason" for an assignment.
98 */
99 boolean locked();
100
101 /**
102 * Mark a constraint as learnt.
103 */
104
105 void setLearnt();
106
107 /**
108 * Register the constraint to the solver.
109 */
110 void register();
111
112 /**
113 * Rescale the clause activity by a value.
114 *
115 * @param d
116 * the value to rescale the clause activity with.
117 */
118 void rescaleBy(double d);
119
120 /**
121 * Method called when the constraint is to be asserted. It means that the
122 * constraint was learnt during the search and it should now propagate some
123 * truth values. In the clausal case, only one literal should be propagated.
124 * In other cases, it might be different.
125 *
126 * @param s
127 * a UnitPropagationListener to use for unit propagation.
128 */
129 void assertConstraint(UnitPropagationListener s);
130 }