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 /**
31 * Interface providing the unit propagation capability.
32 *
33 * @author leberre
34 */
35 public interface UnitPropagationListener {
36
37 /**
38 * satisfies a literal
39 *
40 * @param p
41 * a literal
42 * @return true if the assignment looks possible, false if a conflict
43 * occurs.
44 */
45 public abstract boolean enqueue(int p);
46
47 /**
48 * satisfies a literal
49 *
50 * @param p
51 * a literal
52 * @param from
53 * a reason explaining why p should be satisfied.
54 * @return true if the assignment looks possible, false if a conflict
55 * occurs.
56 */
57 public abstract boolean enqueue(int p, Constr from);
58
59 /**
60 * Unset a unit clause. The effect of such method is to unset all truth
61 * values on the stack until the given literal is found (that literal
62 * included).
63 *
64 * @param p
65 * @since 2.1
66 */
67 public void unset(int p);
68 }