// -*- coding: utf-8 -*-
// Copyright (C) 2010, 2012, 2014, 2015 Laboratoire de Recherche et
// Développement de l'Epita (LRDE).
// Copyright (C) 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 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/>.

#include "simpfg.hh"

namespace spot
{
  formula simplify_f_g(formula p)
  {
    // 1 U p = Fp
    if (p.is(op::U) && p[0].is_tt())
      return formula::F(p[1]);
    // 0 R p = Gp
    if (p.is(op::R) && p[0].is_ff())
      return formula::G(p[1]);
    // p W 0 = Gp
    if (p.is(op::W) && p[1].is_ff())
      return formula::G(p[0]);
    // p M 1 = Fp
    if (p.is(op::M) && p[1].is_tt())
      return formula::F(p[0]);
    return p.map(simplify_f_g);
  }
}