// -*- coding: utf-8 -*-
// Copyright (C) 2012, 2013 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_SIMULATION_HH
# define SPOT_TGBAALGOS_SIMULATION_HH

namespace spot
{
  class tgba;

  /// \addtogroup tgba_reduction
  /// @{

  /// @{
  /// \brief Attempt to reduce the automaton by direct simulation.
  ///
  /// When the suffixes (letter and acceptance conditions) reachable
  /// from one state are included in the suffixes seen by another one,
  /// the former state can be merged into the latter.  The algorithm is
  /// based on the following paper, but generalized to handle TGBA
  /// directly.
  ///
  /// \verbatim
  /// @InProceedings{ etessami.00.concur,
  ///   author        = {Kousha Etessami and Gerard J. Holzmann},
  ///   title         = {Optimizing {B\"u}chi Automata},
  ///   booktitle     = {Proceedings of the 11th International Conference on
  ///	  	      Concurrency Theory (Concur'00)},
  ///   pages         = {153--167},
  ///   year          = {2000},
  ///   editor        = {C. Palamidessi},
  ///   volume        = {1877},
  ///   series        = {Lecture Notes in Computer Science},
  ///   address       = {Pennsylvania, USA},
  ///   publisher     = {Springer-Verlag}
  /// }
  /// \endverbatim
  ///
  /// Our reconstruction of the quotient automaton based on this
  /// suffix-inclusion relation will also improve determinism.
  ///
  /// We recommend to call scc_filter() to first simplify the
  /// automaton that should be reduced by simulation.
  ///
  /// Reducing an automaton by simulation does not change the number
  /// of acceptance conditions.  In some rare cases (1 out of more
  /// than 500 in our benchmark), the reduced automaton will use more
  /// acceptance conditions than necessary, and running scc_filter()
  /// again afterwards will remove these superfluous conditions.
  ///
  /// \param automaton the automaton to simulate.
  /// \return a new automaton which is at worst a copy of the received
  /// one
  tgba* simulation(const tgba* automaton);
  tgba* simulation_sba(const tgba* automaton);
  /// @}

  /// @{
  /// \brief Attempt to reduce the automaton by reverse simulation.
  ///
  /// When the prefixes (letter and acceptance conditions) leading to
  /// one state are included in the prefixes leading to one, the former
  /// state can be merged into the latter.
  ///
  /// Reverse simulation is discussed in the following paper, bu
  /// following paper, but generalized to handle TGBA directly.
  /// \verbatim
  /// @InProceedings{ somenzi.00.cav,
  ///   author	      = {Fabio Somenzi and Roderick Bloem},
  ///   title	      = {Efficient {B\"u}chi Automata for {LTL} Formul{\ae}},
  ///   booktitle     = {Proceedings of the 12th International Conference on
  ///                    Computer Aided Verification (CAV'00)},
  ///   pages         = {247--263},
  ///   year          = {2000},
  ///   volume        = {1855},
  ///   series        = {Lecture Notes in Computer Science},
  ///   address       = {Chicago, Illinois, USA},
  ///   publisher     = {Springer-Verlag}
  /// }
  /// \endverbatim
  ///
  /// Our reconstruction of the quotient automaton based on this
  /// prefix-inclusion relation will also improve codeterminism.
  ///
  /// We recommend to call scc_filter() to first simplify the
  /// automaton that should be reduced by cosimulation.
  ///
  /// Reducing an automaton by reverse simulation (1) does not change
  /// the number of acceptance conditions so the resulting automaton
  /// may have superfluous acceptance conditions, and (2) can create
  /// SCCs that are terminal and non-accepting.  For these reasons,
  /// you should call scc_filer() to prune useless SCCs and acceptance
  /// conditions afterwards.
  ///
  /// If you plan to run both simulation() and cosimulation() on the
  /// same automaton, you should start with simulation() so that the
  /// codeterminism improvements achieved by cosimulation() does not
  /// hinder the determinism improvements attempted by simulation().
  /// (This of course assumes that you prefer determinism over
  /// codeterminism.)
  ///
  /// \param automaton the automaton to simulate.
  /// \return a new automaton which is at worst a copy of the received
  /// one
  tgba* cosimulation(const tgba* automaton);
  tgba* cosimulation_sba(const tgba* automaton);
  /// @}

  /// @{
  /// \brief Iterate simulation() and cosimulation().
  ///
  /// Runs simulation(), cosimulation(), and scc_filter() in a loop,
  /// until the automaton does not change size (states and
  /// transitions).
  ///
  /// We recommend to call scc_filter() to first simplify the
  /// automaton that should be reduced by iterated simulations, since
  /// this algorithm will only call scc_filter() at the end of the
  /// loop.
  ///
  /// \param automaton the automaton to simulate.
  /// \return a new automaton which is at worst a copy of the received
  /// one
  tgba* iterated_simulations(const tgba* automaton);
  tgba* iterated_simulations_sba(const tgba* automaton);
  /// @}


  tgba* dont_care_simulation(const tgba* t, int limit = -1);

  tgba*
  dont_care_iterated_simulations(const tgba* t, int limit = -1);


  /// @}
} // End namespace spot.



#endif // !SPOT_TGBAALGOS_SIMULATION_HH