spot/src/tgbaalgos/magic.hh

// Copyright (C) 2003, 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
// et Marie Curie.
//
// 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 2 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 Spot; see the file COPYING.  If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.

#ifndef SPOT_TGBAALGOS_MAGIC_HH
# define SPOT_TGBAALGOS_MAGIC_HH

#include <cstddef>

namespace spot
{
  class tgba;
  class emptiness_check;

  /// \addtogroup emptiness_check_algorithms
  /// @{

  /// \brief Returns an emptiness checker on the spot::tgba automaton \a a.
  ///
  /// \pre The automaton \a a must have at most one accepting condition (i.e.
  /// it is a TBA).
  ///
  /// During the visit of \a a, the returned checker stores explicitely all
  /// the traversed states.
  /// The method \a check() of the checker can be called several times
  /// (until it returns a null pointer) to enumerate all the visited accepting
  /// paths. The implemented algorithm is the following:
  ///
  /// \verbatim
  /// procedure check ()
  /// begin
  ///   call dfs_blue(s0);
  /// end;
  ///
  /// procedure dfs_blue (s)
  /// begin
  ///   s.color = blue;
  ///   for all t in post(s) do
  ///     if t.color == white then
  ///       call dfs_blue(t);
  ///     end if;
  ///     if (the edge (s,t) is accepting) then
  ///       target = s;
  ///       call dfs_red(t);
  ///     end if;
  ///   end for;
  /// end;
  ///
  /// procedure dfs_red(s)
  /// begin
  ///   s.color = red;
  ///   if s == target then
  ///     report cycle
  ///   end if;
  ///   for all t in post(s) do
  ///     if t.color != red then
  ///       call dfs_red(t);
  ///     end if;
  ///   end for;
  /// end;
  /// \endverbatim
  ///
  /// This algorithm is an adaptation to TBA of the one
  /// (which deals with accepting states) presented in
  ///
  /// \verbatim
  ///  Article{         courcoubertis.92.fmsd,
  ///    author        = {Costas Courcoubetis and Moshe Y. Vardi and Pierre
  ///                    Wolper and Mihalis Yannakakis},
  ///    title         = {Memory-Efficient Algorithm for the Verification of
  ///                    Temporal Properties},
  ///    journal       = {Formal Methods in System Design},
  ///    pages         = {275--288},
  ///    year          = {1992},
  ///    volume        = {1}
  ///  }
  /// \endverbatim
  ///
  emptiness_check* explicit_magic_search(const tgba *a);

  /// \brief Returns an emptiness checker on the spot::tgba automaton \a a.
  ///
  /// \pre The automaton \a a must have at most one accepting condition (i.e.
  /// it is a TBA).
  ///
  /// During the visit of \a a, the returned checker does not store explicitely
  /// the traversed states but uses the bit-state hashing technic presented in:
  ///
  /// \verbatim
  /// @book{Holzmann91,
  ///    author = {G.J. Holzmann},
  ///    title = {Design and Validation of Computer Protocols},
  ///    publisher = {Prentice-Hall},
  ///    address = {Englewood Cliffs, New Jersey},
  ///    year = {1991}
  /// }
  /// \endverbatim
  ///
  /// Consequently, the detection of an acceptence cycle is not ensured. The
  /// implemented algorithm is the same as the one of
  /// spot::explicit_magic_search.
  ///
  /// \sa spot::explicit_magic_search
  ///
  emptiness_check* bit_state_hashing_magic_search(const tgba *a, size_t size);

  /// @}
}

#endif // SPOT_TGBAALGOS_MAGIC_HH