01: /*
02: * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
03: *
04: * This library is free software; you can redistribute it and/or
05: * modify it under the terms of the GNU Lesser General Public
06: * License as published by the Free Software Foundation; either
07: * version 2 of the License, or (at your option) any later version.
08: *
09: * This library is distributed in the hope that it will be useful,
10: * but WITHOUT ANY WARRANTY; without even the implied warranty of
11: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12: * Lesser General Public License for more details.
13: *
14: * You should have received a copy of the GNU Lesser General Public
15: * License along with this library; if not, write to the Free Software
16: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17: */
18: package org.mandarax.kernel;
19:
20: /**
21: * Interface for strategies defining the order of literals that is used by
22: * the inference engine when it attempts to unify the literals with a clause.
23: * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
24: * @version 3.4 <7 March 05>
25: * @since 1.1
26: */
27: public interface SelectionPolicy {
28:
29: /**
30: * Return an array of integers specifying in which order the inference engine
31: * should attempt to unify the literals with the candidate.
32: * The order of clauses matters, this order may have an important impact on performance of a proof!
33: * E.g., if {A,B,C} is a goal (all symbols represent negative literals),
34: * then a left most selection rule would mean that we first try to unify A with
35: * appliedClaue, then B and finally C. The array returned should then be {0,1,2}.
36: * @return int[] the positions
37: * @param goal the goal
38: * @param appliedClause the clause that should be used to prove the goal
39: */
40: int[] getOrderedPositions(Clause goal, Clause appliedClause);
41: }
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