Add a new library to generate formulas and automata.

This library, called libspotgen, gathers functions to generate classes
of automata found in the literature.
Related to #254.

* NEWS, README: Mention the modification.
* Makefile.am, debian/control, debian/libspotgen0.install: Build the new
  library in a separate package.
* spot/gen/automata.hh, spot/gen/automata.cc: Add a family of co-Büchi
  automata.
* configure.ac, spot/Makefile.am, spot/gen/Makefile.am: Build the new
  library.

Makefile.am

@@ -49,6 +49,7 @@ DEBIAN =					\
   debian/libbddx-dev.install			\
   debian/libspot0.install			\
   debian/libspotltsmin0.install			\
+	debian/libspotgen0.install \
   debian/libspot-dev.install			\
   debian/python3-spot.examples			\
   debian/python3-spot.install			\

NEWS

@@ -10,6 +10,10 @@ New in spot 2.3.3.dev (not yet released)
 
   Library:
 
+  - Add a new library libspotgen. It is intended to be place to gather
+    functions that generate classes of formulas and automata from the
+    literature. This separation should ease future development.
+
   - spot::sum() and spot::sum_and() implements the union and the
     intersection of two automatons, respectively.
 

README

@@ -186,6 +186,7 @@ spot/             Sources for libspot.
    twa/           TωA objects and cousins (Transition-based ω-Automata).
    twaalgos/      Algorithms on TωA.
       gtec/       Couvreur's Emptiness-Check.
+   gen/           Sources for libspotgen.
 bin/              Command-line tools built on top of libspot.
    man/           Man pages for the above tools.
 tests/            Test suite.

configure.ac

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright (C) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+# Copyright (C) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016-2017,
 # 2017 Laboratoire de Recherche et Développement de l'Epita (LRDE).
 # Copyright (C) 2003, 2004, 2005, 2006, 2007 Laboratoire
 # d'Informatique de Paris 6 (LIP6), département Systèmes Répartis
@@ -279,6 +279,7 @@ AC_CONFIG_FILES([
   spot/twaalgos/gtec/Makefile
   spot/twaalgos/Makefile
   spot/twa/Makefile
+  spot/gen/Makefile
   python/ajax/Makefile
   python/Makefile
   tests/core/defs

debian/control

@@ -11,7 +11,7 @@ Architecture: any
 Section: science
 Recommends: graphviz
 Suggests: libspot-dev, spot-doc, python3-spot
-Depends: libspot0 (>= ${source:Version}), libspot0 (<< ${source:Version}.1~), ${shlibs:Depends}, ${misc:Depends}
+Depends: ${shlibs:Depends}, ${misc:Depends}, libspot0 (>= ${source:Version}), libspot0 (<< ${source:Version}.1~), libspotgen0 (>= ${source:Version}), libspotgen0 (<< ${source:Version}.1~)
 Description: model checking and omega-automata manipulation library
  Tools to manipulate omega-automata as well as
  linear-time temporal logic (LTL & PSL).
@@ -54,11 +54,19 @@ Description: headers for the BuDDy library
 Package: libspotltsmin0
 Architecture: any
 Section: science
-Recommends: graphviz
 Suggests: libspot-dev
 Depends: ${shlibs:Depends}, ${misc:Depends}, libspot0 (>= ${source:Version}), libspot0 (<< ${source:Version}.1~)
 Description: interface between Spot and LTSmin models
- Library load LTSmin models as Spot automata.
+ Library for loading LTSmin models as Spot automata.
+
+Package: libspotgen0
+Architecture: any
+Section: science
+Suggests: libspot-dev
+Depends: ${shlibs:Depends}, ${misc:Depends}, libspot0 (>= ${source:Version}), libspot0 (<< ${source:Version}.1~)
+Description: functions for generating formulas and automata in Spot
+  Library for generating families of formulas and automata
+  taken from the literature.
 
 Package: spot-doc
 Section: doc

debian/libspotgen0.install

@@ -0,0 +1 @@
+usr/lib/*-*/libspotgen.so.*

spot/Makefile.am

@@ -25,7 +25,7 @@ AUTOMAKE_OPTIONS = subdir-objects
 # List directories in the order they must be built.  Keep tests at the
 # end, after building '.' (since the current directory contains
 # libspot.la needed by the tests)
-SUBDIRS = misc priv tl graph twa twaalgos ta taalgos kripke	\
+SUBDIRS = misc priv tl graph twa twaalgos ta taalgos kripke	gen \
           parseaut parsetl . ltsmin
 
 lib_LTLIBRARIES = libspot.la

spot/gen/Makefile.am

@@ -0,0 +1,30 @@
+## -*- coding: utf-8 -*-
+## Copyright (C) 2017 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/>.
+
+AM_CPPFLAGS = -I$(top_builddir) -I$(top_srcdir) $(BUDDY_CPPFLAGS)
+AM_CXXFLAGS = $(WARNING_CXXFLAGS)
+
+spotgendir = $(pkgincludedir)/gen
+spotgen_HEADERS = automata.hh
+
+lib_LTLIBRARIES = libspotgen.la
+libspotgen_la_SOURCES = \
+  automata.cc
+#libspotgen_la_LDFLAGS = $(BUDDY_LDFLAGS) -no-undefined $(SYMBOLIC_LDFLAGS)
+

spot/gen/automata.cc

@@ -0,0 +1,89 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2017 Laboratoire de Recherche et Developpement 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/>.
+
+#include <spot/gen/automata.hh>
+#include <spot/twa/formula2bdd.hh>
+#include <spot/tl/parse.hh>
+
+namespace spot
+{
+  namespace gen
+  {
+
+    twa_graph_ptr
+    ks_cobuchi(unsigned n)
+    {
+      // the alphabet has four letters:
+      // i, s (for sigma), p (for pi), h (for hash)
+      // we encode this four letters alphabet thanks to two AP a and b
+      // the exact encoding is not important
+      // each letter is a permutation of the set {1..2n}
+      // s = (1 2 .. 2n) the rotation
+      // p = (1 2) the swap of the first two elements
+      // i is the identity
+      // d is the identity on {2..2n} but is undefined on 1
+
+      // the automaton has 2n+1 states, numbered from 0 to 2n
+      // 0 is the initial state and the only non-deterministic state
+
+      auto dict = make_bdd_dict();
+      auto aut = make_twa_graph(dict);
+
+      // register aps
+      aut->register_ap("a");
+      aut->register_ap("b");
+
+      // retrieve the four letters, and name them
+      bdd i = formula_to_bdd(parse_formula("a&&b"), dict, aut);
+      bdd s = formula_to_bdd(parse_formula("a&&!b"), dict, aut);
+      bdd p = formula_to_bdd(parse_formula("!a&&b"), dict, aut);
+      bdd h = formula_to_bdd(parse_formula("!a&&!b"), dict, aut);
+
+      // actually build the automaton
+      aut->new_states(2*n+1);
+      aut->set_init_state(0);
+      aut->set_acceptance(1, acc_cond::acc_code::cobuchi());
+
+      // from 0, we can non-deterministically jump to any state (except 0) with
+      // any letter.
+      for (unsigned q = 1; q <= 2*n; ++q)
+        aut->new_edge(0, q, bddtrue, {0});
+      // i is the identity
+      for (unsigned q = 1; q <= 2*n; ++q)
+        aut->new_edge(q, q, i);
+      // p swaps 1 and 2, and leaves all other states invariant
+      aut->new_edge(1, 2, p);
+      aut->new_edge(2, 1, p);
+      for (unsigned q = 3; q <= 2*n; ++q)
+        aut->new_edge(q, q, p);
+      // s does to next state (mod 2*n, 0 excluded)
+      aut->new_edge(2*n, 1, s);
+      for (unsigned q = 1; q < 2*n; ++q)
+        aut->new_edge(q, q+1, s);
+      // h is the same as i, except on 1 where it goes back to the initial state
+      aut->new_edge(1, 0, h);
+      for (unsigned q = 2; q <= 2*n; ++q)
+        aut->new_edge(q, q, h);
+
+      aut->merge_edges();
+      return aut;
+    }
+  }
+}
+

spot/gen/automata.hh

@@ -0,0 +1,48 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2017 Laboratoire de Recherche et Developpement 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
+{
+  namespace gen
+  {
+    /// \brief A family of co-Büchi automata.
+    ///
+    /// ks_cobuchi(n) is a co-Büchi automaton of size 2n+1 that is
+    /// good-for-games and that has no equivalent deterministic co-Büchi
+    /// automaton with less than 2^n / (2n+1) states.
+    /// For details and other classes, see:
+    ///
+    /// @InProceedings{kuperberg2015determinisation,
+    ///     author={Kuperberg, Denis and Skrzypczak, Micha{\l}},
+    ///     title={On Determinisation of Good-for-Games Automata},
+    ///     booktitle={International Colloquium on Automata, Languages, and
+    ///                Programming},
+    ///     pages={299--310},
+    ///     year={2015},
+    ///     organization={Springer}
+    /// }
+    SPOT_API twa_graph_ptr
+    ks_cobuchi(unsigned n);
+  }
+}
+