CAR: new algorithm for paritizing

* NEWS: Mention it.
* spot/twaalgos/car.cc, spot/twaalgos/car.hh, tests/python/car.py:
New files.
* spot/twaalgos/Makefile.am, tests/Makefile.am: Add them.
* python/spot/impl.i: Include CAR.
* spot/twa/acc.cc, spot/twa/acc.hh, spot/twa/twagraph.cc,
spot/twa/twagraph.hh: Add supporting methods.

spot/twaalgos/Makefile.am

@@ -59,6 +59,7 @@ twaalgos_HEADERS = \
   isunamb.hh \
   isweakscc.hh \
   langmap.hh \
+  car.hh \
   lbtt.hh \
   ltl2taa.hh \
   ltl2tgba_fm.hh \
@@ -128,6 +129,7 @@ libtwaalgos_la_SOURCES = \
   isunamb.cc \
   isweakscc.cc \
   langmap.cc \
+  car.cc \
   lbtt.cc \
   ltl2taa.cc \
   ltl2tgba_fm.cc \

spot/twaalgos/car.hh

@@ -0,0 +1,59 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2012-2019 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/>.
+
+#pragma once
+
+#include <spot/twa/twagraph.hh>
+
+namespace spot
+{
+/// \ingroup twa_acc_transform
+/// \brief Take an automaton with any acceptance condition and return an
+/// equivalent parity automaton.
+///
+/// The parity condition of the returned automaton is max even or
+/// max odd.
+/// If \a search_ex is true, when we move several elements, we
+/// try to find an order  such that the new permutation already exists.
+/// If \a partial_degen is true, we apply a partial degeneralization to remove
+// occurences of Fin | Fin and Inf & Inf.
+/// If \a scc_acc_clean is true, we remove for each SCC the colors that don't
+// appear.
+/// If \a parity_equiv is true, we check if there exists a permutations of
+// colors such that the acceptance
+/// condition is a partity condition.
+/// If \a use_last is true, we use the most recent state when looking for an
+// existing state.
+/// If \a pretty_print is true, we give a name to the states describing the
+// state of the aut_ and the permutation.
+
+  SPOT_API twa_graph_ptr
+  remove_false_transitions(const twa_graph_ptr a);
+
+  SPOT_API twa_graph_ptr
+  car(const twa_graph_ptr &aut,
+    bool search_ex = true,
+    bool partial_degen = true,
+    bool scc_acc_clean = true,
+    bool parity_equiv = true,
+    bool use_last = true,
+    bool parity_prefix = true,
+    bool rabin_to_buchi = true,
+    bool pretty_print = false);
+} // namespace spot