Adding function to test if two büchi automata are isomorphic.

And add the corresponding --isomorphic=FILENAME option to autfilt.

* src/tgbaalgos/are_isomorphic.cc, src/tgbaalgos/are_isomorphic.hh:
New.
* src/tgbaalgos/Makefile.am: Add it.
* src/bin/autfilt.cc: Add --isomorphic option.
* src/tgbatest/isomorph.test: Test it.
* src/tgbatest/Makefile.am: Add it.

src/tgbaalgos/are_isomorphic.hh

@@ -0,0 +1,41 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2014 Laboratoire de Recherche et
+// Développement de l'Epita (LRDE).
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// Spot is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+// or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+// License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef SPOT_TGBAALGOS_ARE_ISOMORPHIC_HH
+# define SPOT_TGBAALGOS_ARE_ISOMORPHIC_HH
+
+#include "tgba/tgbagraph.hh"
+
+namespace spot
+{
+  /// \ingroup tgba_misc
+  /// \brief Check whether two automata are isomorphic.
+  /// Two automata a1 and a2 are said to be isomorphic if there is a bijection
+  /// f between the states of a1 and a2 such that for every pair of state (s1,
+  /// s2) of a1:
+  /// - there is a transition from s1 to s2 iff there is a transition from f(s1)
+  /// to f(s2)
+  /// - if there is such a transition, then the acceptance set and acceptance
+  /// condition are the same on the transition from s1 to s2 and from f(s1) to
+  /// f(s2)
+  SPOT_API bool are_isomorphic(const const_tgba_digraph_ptr a1,
+                               const const_tgba_digraph_ptr a2);
+}
+
+#endif