01 /* This file is part of the project "Hilbert II" - http://www.qedeq.org
02 *
03 * Copyright 2000-2011, Michael Meyling <mime@qedeq.org>.
04 *
05 * "Hilbert II" is free software; you can redistribute
06 * it and/or modify it under the terms of the GNU General Public
07 * License as published by the Free Software Foundation; either
08 * version 2 of the License, or (at your option) any later version.
09 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 */
15
16 package org.qedeq.kernel.se.base.module;
17
18 import org.qedeq.kernel.se.base.list.Element;
19
20
21 /**
22 * Rule of universal generalization.
23 * <pre>
24 * A -> B(x)
25 * -------------------
26 * A -> forall x B(x)
27 * </pre>
28 *
29 * @author Michael Meyling
30 */
31 public interface Universal extends Reason {
32
33 /**
34 * Get reference to formula. Usually this a formula of type A -> B(x)
35 *
36 * @return Reference to previously proved formula.
37 */
38 public String getReference();
39
40 /**
41 * Get free subject variable we want to quantify over.
42 *
43 * @return Free subject variable.
44 */
45 public Element getSubjectVariable();
46
47 }
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