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# equivalent.hxx

    00001 // equivalent.hxx: this file is part of the Vaucanson project.
    00002 //
    00003 // Vaucanson, a generic library for finite state machines.
    00004 //
    00005 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 The Vaucanson Group.
    00006 //
    00007 // This program is free software; you can redistribute it and/or
    00008 // modify it under the terms of the GNU General Public License
    00009 // as published by the Free Software Foundation; either version 2
    00010 // of the License, or (at your option) any later version.
    00011 //
    00012 // The complete GNU General Public Licence Notice can be found as the
    00013 // `COPYING' file in the root directory.
    00014 //
    00015 // The Vaucanson Group consists of people listed in the `AUTHORS' file.
    00016 //
    00017 #ifndef VCSN_ALGORITHMS_EQUIVALENT_HXX
    00018 # define VCSN_ALGORITHMS_EQUIVALENT_HXX
    00019
    00020 # include <vaucanson/algorithms/equivalent.hh>
    00021 # include <vaucanson/algorithms/determinize.hh>
    00022 # include <vaucanson/algorithms/is_deterministic.hh>
    00023 # include <vaucanson/algorithms/complement.hh>
    00024 # include <vaucanson/algorithms/complete.hh>
    00025 # include <vaucanson/algorithms/trim.hh>
    00026 # include <vaucanson/algorithms/product.hh>
    00027
    00028 # include <vaucanson/algebra/implementation/series/rat/exp.hh>
    00029 # include <vaucanson/misc/usual_macros.hh>
    00030
    00031
    00032 namespace vcsn
    00033 {
    00034
    00035   template<typename SA, typename A,
    00036            typename SB, typename B>
    00037   bool
    00038   do_are_equivalent(const AutomataBase<SA>&, const A& a,
    00039                     const AutomataBase<SB>&, const B& b)
    00040   {
    00041     A pos_a(a);
    00042     B pos_b(b);
    00043
    00044     if (not is_realtime(pos_a))
    00045       realtime_here(pos_a);
    00046     if (not is_realtime(pos_b))
    00047       realtime_here(pos_b);
    00048
    00049     // L(a) = L(b) \iff (L(b) \subset L(a) \land L(a) \subset L(b))
    00050
    00051     // L(b) \subset L(a)  \iff   \overline{L(a)}\cap L(b)=\emptyset
    00052     // We compute the latter with complement and product.
    00053     A neg_a(pos_a);
    00054     if (not is_deterministic(neg_a))
    00055       neg_a = determinize(neg_a);
    00056     else if (not is_complete(neg_a))
    00057       complete_here(neg_a);
    00058     complement_here(neg_a);
    00059     if (trim(product(neg_a, pos_b)).states().size() != 0)
    00060       return false;
    00061
    00062     // L(a) \subset L(b)  \iff   L(a)\cap\overline{L(b)}=\emptyset
    00063     A neg_b(pos_b);
    00064     if (not is_deterministic(neg_b))
    00065       neg_b = determinize(neg_b);
    00066     else if(not is_complete(neg_b))
    00067       complete_here(neg_b);
    00068     complement_here(neg_b);
    00069     return (trim(product(pos_a, neg_b)).states().size() == 0);
    00070   }
    00071
    00072
    00073   template<typename S, typename A, typename B>
    00074   bool
    00075   are_equivalent(const Element<S, A>& a, const Element<S, B>& b)
    00076   {
    00077     return do_are_equivalent(a.structure(), a,
    00078                              b.structure(), b);
    00079   }
    00080
    00081 } // vcsn
    00082
    00083 #endif // ! VCSN_ALGORITHMS_EQUIVALENT_HXX