// -*- coding: utf-8 -*-
// Copyright (C) 2009, 2010, 2011, 2012 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 .
#ifndef SPOT_TGBAALGOS_MINIMIZE_HH
# define SPOT_TGBAALGOS_MINIMIZE_HH
# include "tgba/tgbaexplicit.hh"
# include "ltlast/formula.hh"
namespace spot
{
/// \addtogroup tgba_reduction
/// @{
/// \brief Construct a minimal deterministic monitor.
///
/// The automaton will be converted into minimal deterministic
/// monitor. All useless SCCs should have been previously removed
/// (using scc_filter() for instance). Then the automaton will be
/// determinized and minimized using the standard DFA construction
/// as if all states were accepting states.
///
/// For more detail about monitors, see the following paper:
/// \verbatim
/// @InProceedings{ tabakov.10.rv,
/// author = {Deian Tabakov and Moshe Y. Vardi},
/// title = {Optimized Temporal Monitors for SystemC{$^*$}},
/// booktitle = {Proceedings of the 10th International Conferance
/// on Runtime Verification},
/// pages = {436--451},
/// year = 2010,
/// volume = {6418},
/// series = {Lecture Notes in Computer Science},
/// month = nov,
/// publisher = {Spring-Verlag}
/// }
/// \endverbatim
/// (Note: although the above paper uses Spot, this function did not
/// exist in Spot at that time.)
///
/// \param a the automaton to convert into a minimal deterministic monitor
/// \pre Dead SCCs should have been removed from \a a before
/// calling this function.
sba_explicit_number* minimize_monitor(const tgba* a);
/// \brief Minimize a Büchi automaton in the WDBA class.
///
/// This takes a TGBA whose language is representable by a Weak
/// Deterministic Büchi Automaton, and construct a minimal WDBA for
/// this language. This essentially chains three algorithms:
/// determinization, acceptance adjustment (Löding's coloring
/// algorithm), and minimization (using a Moore-like approache).
///
/// If the input automaton does not represent a WDBA language,
/// the resulting automaton is still a WDBA, but it will not
/// be equivalent to the original automaton. Use the
/// minimize_obligation() function if you are not sure whether
/// it is safe to call this function.
///
/// Please see the following paper for a discussion of this
/// technique.
///
/// \verbatim
/// @InProceedings{ dax.07.atva,
/// author = {Christian Dax and Jochen Eisinger and Felix Klaedtke},
/// title = {Mechanizing the Powerset Construction for Restricted
/// Classes of {$\omega$}-Automata},
/// year = 2007,
/// series = {Lecture Notes in Computer Science},
/// publisher = {Springer-Verlag},
/// volume = 4762,
/// booktitle = {Proceedings of the 5th International Symposium on
/// Automated Technology for Verification and Analysis
/// (ATVA'07)},
/// editor = {Kedar S. Namjoshi and Tomohiro Yoneda and Teruo Higashino
/// and Yoshio Okamura},
/// month = oct
/// }
/// \endverbatim
sba_explicit_number* minimize_wdba(const tgba* a);
/// \brief Minimize an automaton if it represents an obligation property.
///
/// This function attempts to minimize the automaton \a aut_f using the
/// algorithm implemented in the minimize_wdba() function, and presented
/// by the following paper:
///
/// \verbatim
/// @InProceedings{ dax.07.atva,
/// author = {Christian Dax and Jochen Eisinger and Felix Klaedtke},
/// title = {Mechanizing the Powerset Construction for Restricted
/// Classes of {$\omega$}-Automata},
/// year = 2007,
/// series = {Lecture Notes in Computer Science},
/// publisher = {Springer-Verlag},
/// volume = 4762,
/// booktitle = {Proceedings of the 5th International Symposium on
/// Automated Technology for Verification and Analysis
/// (ATVA'07)},
/// editor = {Kedar S. Namjoshi and Tomohiro Yoneda and Teruo Higashino
/// and Yoshio Okamura},
/// month = oct
/// }
/// \endverbatim
///
/// Because it is hard to determine if an automaton corresponds
/// to an obligation property, you should supply either the formula
/// \a f expressed by the automaton \a aut_f, or \a aut_neg_f the negation
/// of the automaton \a aut_neg_f.
///
/// \param aut_f the automaton to minimize
/// \param f the LTL formula represented by the automaton \a aut_f
/// \param aut_neg_f an automaton representing the negation of \a aut_f
/// \return a new tgba if the automaton could be minimized, aut_f if
/// the automaton cannot be minimized, 0 if we do not if if the
/// minimization is correct because neither \a f nor \a aut_neg_f
/// were supplied.
///
/// The function proceeds as follows. If the formula \a f or the
/// automaton \a aut can easily be proved to represent an obligation
/// formula, then the result of minimize(aut) is
/// returned. Otherwise, if \a aut_neg_f was not supplied but \a f
/// was, \a aut_neg_f is built from the negation of \a f. Then we
/// check that product(aut,!minimize(aut_f)) and
/// product(aut_neg_f,minize(aut)) are both empty. If they
/// are, the the minimization was sound. (See the paper for full
/// details.)
///
/// If \a reject_bigger is set, this function will return the input
/// automaton \a aut_f when the minimized WDBA has more states than
/// the input automaton. (More states are possible because of
/// determinization step during minimize_wdba().) Note that
/// checking the size of the minimized WDBA occurs before ensuring
/// that the minimized WDBA is correct.
tgba* minimize_obligation(const tgba* aut_f,
const ltl::formula* f = 0,
const tgba* aut_neg_f = 0,
bool reject_bigger = false);
/// @}
}
#endif /* !SPOT_TGBAALGOS_MINIMIZE_HH */