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ltl2tgba_fm: don't tag weak automata if unambiguous is used

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Part of a bug reported by Simon Jantsch.  Test cases in next patch.

* spot/twaalgos/ltl2tgba_fm.cc: Here.
* NEWS: Mention the bug.
This commit is contained in:
Alexandre Duret-Lutz 2019-02-02 14:37:39 +01:00
parent ea9d894d01
commit d4203c8ad0
2 changed files with 31 additions and 20 deletions
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3
NEWS
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@ -25,6 +25,9 @@ New in spot 2.7.0.dev (not yet release)
tools such as ltlfilt, ltlcross, or ltl2tgba were run on files of
formulas with MS-DOS line endings.
- The core translation for unambiguous automata was incorrectly
tagging some non-weak automata as weak.
New in spot 2.7 (2018-12-11)
Command-line tools:

48
spot/twaalgos/ltl2tgba_fm.cc
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2008-2018 Laboratoire de Recherche et Développement
// Copyright (C) 2008-2019 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2003-2006 Laboratoire d'Informatique de Paris 6
// (LIP6), département Systèmes Répartis Coopératifs (SRC), Université
@ -1926,14 +1926,14 @@ namespace spot
twa_graph_ptr a = make_twa_graph(dict);
auto namer = a->create_namer<formula>();
// Translating syntactic persistence will give a weak automaton, unless
// the unambiguous option is used. In the "unambiguous" case, formulas
// Even if the input is a persistence formula, the unambiguous option might
// cause the resulting automaton not to be weak. For instance formulas
// such as "FGa | FGb" (note: not "F(Ga | Gb)") will introduce terms like
// "FGb&GF!a" that are not syntactic persistence.
bool will_be_weak = (unambiguous
? f2.is_syntactic_obligation()
: f2.is_syntactic_persistence());
translate_dict d(a, s, exprop, will_be_weak, unambiguous);
bool one_set_enough = (unambiguous
? f2.is_syntactic_obligation()
: f2.is_syntactic_persistence());
translate_dict d(a, s, exprop, one_set_enough, unambiguous);
// Compute the set of all promises that can possibly occur inside
// the formula. These are the right-hand sides of U or F
@ -2198,21 +2198,29 @@ namespace spot
acc.set_generalized_buchi();
// The unambiguous option can introduce sub-terms that are not
// persistence, hence the resulting automaton might not be weak.
if (will_be_weak)
a->prop_weak(true);
if (f2.is_syntactic_stutter_invariant())
if (orig_f.is_syntactic_stutter_invariant())
a->prop_stutter_invariant(true);
if (orig_f.is_syntactic_guarantee())
{
a->prop_terminal(true);
assert(a->num_sets() <= 1);
}
// We cannot assume weak automata if the unambibuous construction
// is used.
//
// In an obligation formula such as (b W Ga)&F!a, initial state is
// not accepting and goes to a state (b W Ga) that is accepting.
// Adding the unambiguous option will add a back-edge between
// these two states, creating an non-weak SCC.
//
// For guarantee formulas, X(G(b))) -> (!((a) W (G(b)))) has a
// non-weak output.
if (unambiguous)
a->prop_unambiguous(true);
{
a->prop_unambiguous(true);
}
else
{
if (orig_f.is_syntactic_persistence())
a->prop_weak(true);
if (orig_f.is_syntactic_guarantee())
a->prop_terminal(true);
}
// Set the following to true to preserve state names.
a->release_formula_namer(namer, false);