Add an is_unambiguous() function, use it in ltlcross and autfilt

* src/twaalgos/isunamb.hh, src/twaalgos/isunamb.cc: New files.
* src/twaalgos/Makefile.am: Add them.
* src/tests/unambig.test: New file.
* src/tests/Makefile.am: Add it.
* src/bin/ltlcross.cc: Record whether each produced automaton is
ambiguous.
* src/bin/autfilt.cc: Add a --is-unambiguous option.
* NEWS: Mention it.

src/bin/autfilt.cc

@@ -39,6 +39,7 @@
 #include "twaalgos/product.hh"
 #include "twaalgos/isdet.hh"
 #include "twaalgos/stutter.hh"
+#include "twaalgos/isunamb.hh"
 #include "misc/optionmap.hh"
 #include "misc/timer.hh"
 #include "misc/random.hh"
@@ -80,6 +81,7 @@ enum {
   OPT_IS_COMPLETE,
   OPT_IS_DETERMINISTIC,
   OPT_IS_EMPTY,
+  OPT_IS_UNAMBIGUOUS,
   OPT_KEEP_STATES,
   OPT_MASK_ACC,
   OPT_MERGE,
@@ -179,6 +181,8 @@ static const argp_option options[] =
       "keep deterministic automata", 0 },
     { "is-empty", OPT_IS_EMPTY, 0, 0,
       "keep automata with an empty language", 0 },
+    { "is-unambiguous", OPT_IS_UNAMBIGUOUS, 0, 0,
+      "keep only unambiguous automata", 0 },
     { "intersect", OPT_INTERSECT, "FILENAME", 0,
       "keep automata whose languages have an non-empty intersection with"
       " the automaton from FILENAME", 0 },
@@ -234,6 +238,7 @@ static struct opt_t
 static bool opt_merge = false;
 static bool opt_is_complete = false;
 static bool opt_is_deterministic = false;
+static bool opt_is_unambiguous = false;
 static bool opt_invert = false;
 static range opt_states = { 0, std::numeric_limits<int>::max() };
 static range opt_edges = { 0, std::numeric_limits<int>::max() };
@@ -344,6 +349,9 @@ parse_opt(int key, char* arg, struct argp_state*)
     case OPT_IS_EMPTY:
       opt_is_empty = true;
       break;
+    case OPT_IS_UNAMBIGUOUS:
+      opt_is_unambiguous = true;
+      break;
     case OPT_MERGE:
       opt_merge = true;
       break;
@@ -522,6 +530,10 @@ namespace
 	matched &= is_complete(aut);
       if (opt_is_deterministic)
 	matched &= is_deterministic(aut);
+      if (opt_is_deterministic)
+	matched &= is_deterministic(aut);
+      else if (opt_is_unambiguous)
+	matched &= is_unambiguous(aut);
       if (opt->are_isomorphic)
         matched &= opt->isomorphism_checker->is_isomorphic(aut);
       if (opt_is_empty)

src/bin/ltlcross.cc

@@ -59,6 +59,7 @@
 #include "misc/formater.hh"
 #include "twaalgos/stats.hh"
 #include "twaalgos/isdet.hh"
+#include "twaalgos/isunamb.hh"
 #include "misc/escape.hh"
 #include "misc/hash.hh"
 #include "misc/random.hh"
@@ -293,6 +294,7 @@ struct statistics
   std::vector<double> product_states;
   std::vector<double> product_transitions;
   std::vector<double> product_scc;
+  bool ambiguous;
 
   static void
   fields(std::ostream& os, bool show_exit, bool show_sr)
@@ -316,7 +318,8 @@ struct statistics
 	   "\"nondet_aut\","
 	   "\"terminal_aut\","
 	   "\"weak_aut\","
-	   "\"strong_aut\"");
+	   "\"strong_aut\","
+	   "\"ambiguous_aut\"");
     size_t m = products_avg ? 1U : products;
     for (size_t i = 0; i < m; ++i)
       os << ",\"product_states\",\"product_transitions\",\"product_scc\"";
@@ -353,7 +356,8 @@ struct statistics
 	   << nondeterministic << ','
 	   << terminal_aut << ','
 	   << weak_aut << ','
-	   << strong_aut;
+	   << strong_aut << ','
+	   << ambiguous;
 	if (!products_avg)
 	  {
 	    for (size_t i = 0; i < products; ++i)
@@ -381,7 +385,7 @@ struct statistics
       {
 	size_t m = products_avg ? 1U : products;
 	m *= 3;
-	m += 13 + show_sr * 6;
+	m += 14 + show_sr * 6;
 	os << na;
 	for (size_t i = 0; i < m; ++i)
 	  os << ',' << na;
@@ -688,6 +692,7 @@ namespace
 		st->weak_aut = true;
 	      else
 		st->terminal_aut = true;
+	      st->ambiguous = !spot::is_unambiguous(res);
 	    }
 	}
       output.cleanup();

src/tests/Makefile.am

@@ -211,6 +211,7 @@ TESTS_twa = \
   babiak.test \
   monitor.test \
   dra2dba.test \
+  unambig.test \
   ltlcross4.test \
   ltl2dstar.test \
   ltl2dstar2.test \

src/tests/unambig.test

@@ -0,0 +1,84 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2013, 2015 Laboratoire de Recherche et Developpement
+# de l'Epita
+#
+# 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/>.
+
+. ./defs
+
+set -e
+
+ltl2tgba=../../bin/ltl2tgba
+autfilt=../../bin/autfilt
+
+for f in 'Ga' \
+         'Ga | Gb' \
+         'Ga | GFb' \
+         'Ga | FGb' \
+         'XFGa | GFb | Gc' \
+         '(Ga -> Gb) W c' \
+	 'F(a & !b & (!c W b))'
+do
+  $ltl2tgba -UH "$f" | $autfilt -q --is-unambiguous
+  $ltl2tgba -UH "!($f)" | $autfilt -q --is-unambiguous
+done
+
+for f in FGa
+do
+  $ltl2tgba -H "$f" | $autfilt -qv --is-unambiguous
+  $ltl2tgba -UH "$f" | $autfilt -q --is-unambiguous
+done
+
+# All these should be detected as ambiguous automata
+cat >input<<EOF
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 1 Inf(0)
+--BODY--
+State: 0
+[0] 0
+[1] 0
+[0&1] 0 {0}
+--END--
+HOA: v1
+States: 1
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 2 Inf(0) & Inf(1)
+--BODY--
+State: 0
+[0] 0
+[1] 0 {0}
+[0&1] 0 {0 1}
+--END--
+HOA: v1
+States: 2
+Start: 0
+AP: 2 "a" "b"
+Acceptance: 1 Inf(0)
+--BODY--
+State: 0
+[0] 1 {0}
+[1] 1
+State: 1
+[0] 1 {0}
+--END--
+EOF
+
+run 1 $autfilt -q --is-unambiguous input

src/twaalgos/Makefile.am

@@ -46,6 +46,7 @@ twaalgos_HEADERS = \
   gv04.hh \
   hoa.hh \
   isdet.hh \
+  isunamb.hh \
   isweakscc.hh \
   lbtt.hh \
   ltl2taa.hh \
@@ -101,6 +102,7 @@ libtwaalgos_la_SOURCES = \
   gv04.cc \
   hoa.cc \
   isdet.cc \
+  isunamb.cc \
   isweakscc.cc \
   lbtt.cc \
   ltl2taa.cc \

src/twaalgos/isunamb.cc

@@ -0,0 +1,40 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2013, 2015 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 "isunamb.hh"
+#include "twaalgos/product.hh"
+#include "sccfilter.hh"
+#include "stats.hh"
+#include <set>
+#include <list>
+
+namespace spot
+{
+  bool is_unambiguous(const const_twa_graph_ptr& aut)
+  {
+    if (aut->is_deterministic())
+      return true;
+    auto clean_a = scc_filter_states(aut);
+    auto prod = product(clean_a, clean_a);
+    auto clean_p = scc_filter_states(prod);
+    tgba_statistics sa = stats_reachable(clean_a);
+    tgba_statistics sp = stats_reachable(clean_p);
+    return sa.states == sp.states && sa.transitions == sp.transitions;
+  }
+}

src/twaalgos/isunamb.hh

@@ -0,0 +1,44 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2013, 2015 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 "twa/twagraph.hh"
+
+namespace spot
+{
+  class tgba;
+
+  /// \addtogroup tgba_misc
+  /// @{
+
+  /// \brief Whether the automaton \a aut is unambiguous.
+  ///
+  /// An automaton is unambiguous if each accepted word is
+  /// recognized by only one path.
+  ///
+  /// We check unambiguousity by synchronizing the automaton with
+  /// itself, and then making sure that the co-reachable part of the
+  /// squared automaton has the same size as the co-reachable part of
+  /// the original automaton.
+  SPOT_API bool
+  is_unambiguous(const const_twa_graph_ptr& aut);
+
+  /// @}
+}