01: package org.mandarax.util.comparators;
02:
03: /*
04: * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
05: *
06: * This library is free software; you can redistribute it and/or
07: * modify it under the terms of the GNU Lesser General Public
08: * License as published by the Free Software Foundation; either
09: * version 2 of the License, or (at your option) any later version.
10: *
11: * This library is distributed in the hope that it will be useful,
12: * but WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * Lesser General Public License for more details.
15: *
16: * You should have received a copy of the GNU Lesser General Public
17: * License along with this library; if not, write to the Free Software
18: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19: */
20:
21: import org.mandarax.kernel.Fact;
22:
23: /**
24: * Comparator that prefers facts with less variables.
25: * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
26: * @version 3.4 <7 March 05>
27: * @since 2.2
28: */
29: public class PreferFactsWithLessVariables extends
30: AbstractFactComparator {
31: /**
32: * Constructor.
33: */
34: public PreferFactsWithLessVariables() {
35: super ();
36: }
37:
38: /**
39: * Compare two facts.
40: * @return an integer
41: * @param f1 the first fact
42: * @param f2 the second fact
43: */
44: protected int compareFacts(Fact f1, Fact f2) {
45: return countVariables(f1) - countVariables(f2);
46: }
47:
48: /**
49: * Get a descriptive name.
50: * @return a string
51: */
52: public String getName() {
53: return "prefer facts with less variables";
54: }
55: }
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