alarsyo/spot
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

minimize_wdba: fix handling of input with useless SCCs

Browse source 
* spot/twaalgos/minimize.cc (minimize_wdba): Diminish the color of
terminal SCCs that are incomplete, as if they had a non-accepting
sink as successor.
* spot/twaalgos/strength.hh, spot/twaalgos/strength.cc
(is_terminal_automaton): Add an option to ignore trivial SCC as we did
before, since it matters for deciding membership to the guarantee
class.
(is_safety_mwdba): Rewrite as ...
(is_safety_automaton): ... generalizating to any acceptance, and
ignoring trivial SCCs.
* bin/ltlfilt.cc, python/ajax/spotcgi.in, spot/tl/hierarchy.cc,
tests/core/ikwiad.cc: Adjust usage of is_terminal_automaton and
is_safety_automaton().
* tests/core/hierarchy.test: Add a problematic formula as test-case.
* NEWS: Mention the bug.
This commit is contained in:
Alexandre Duret-Lutz 2017-01-11 18:06:41 +01:00
parent 7d9ce0d6fc
commit c9918f6407
9 changed files with 94 additions and 50 deletions
Download patch file Download diff file Expand all files Collapse all files

11
NEWS
View file

@ -46,7 +46,7 @@ New in spot 2.2.2.dev (Not yet released)
are automata-based and will also match pathological formulas.
* The --format option of ltlfilt/genltl/randltl/ltlgrind learned to
print the class of a formula in the temporal hierachy of Manna &
print the class of a formula in the temporal hierarchy of Manna &
Pnueli using %h. Try to classify the Dwyer & al. patterns with:
genltl --dac --format='%[vw]h' | sort | uniq -c
@ -130,6 +130,15 @@ New in spot 2.2.2.dev (Not yet released)
* The new function mp_class(f) returns the class of the formula
f in the temporal hierarchy of Manna & Pnueli.
Bug fixed:
* The minimize_wdba() function was not correctly minimizing automata
with useless SCCs. This was not an issue for the LTL translation
(where useless SCCs are always removed first), but it was an issue
when deciding if a formula was safety or guarantee. As a
consequence, some tricky safety or guarantee properties were only
recognized as obligations.
New in spot 2.2.2 (2016-12-16)
Build:

6
bin/ltlfilt.cc
View file

@ -734,8 +734,10 @@ namespace
}
else
{
matched &= !guarantee || is_terminal_automaton(min);
matched &= !safety || is_safety_mwdba(min);
spot::scc_info si(min);
matched &= !guarantee
|| is_terminal_automaton(min, &si, true);
matched &= !safety || is_safety_automaton(min, &si);
}
}
// Recurrence properties are those that can be translated to

8
python/ajax/spotcgi.in
View file

@ -1,7 +1,7 @@
#!@PYTHON@
# -*- mode: python; coding: utf-8 -*-
# Copyright (C) 2011, 2012, 2013, 2014, 2015, 2016 Laboratoire de Recherche et
# Développement de l'Epita (LRDE).
# Copyright (C) 2011, 2012, 2013, 2014, 2015, 2016, 2017 Laboratoire de
# Recherche et Développement de l'Epita (LRDE).
#
# This file is part of Spot, a model checking library.
#
@ -511,8 +511,8 @@ if output_type == 'f':
automaton = spot.ltl_to_tgba_fm(f, dict, False, True)
minimized = spot.minimize_obligation(automaton, f)
if minimized != automaton:
g = spot.is_terminal_automaton(minimized)
s = spot.is_safety_mwdba(minimized)
g = spot.is_terminal_automaton(minimized, None, True)
s = spot.is_safety_automaton(minimized)
if s and not f.is_syntactic_safety():
unbufprint('<li>pathologic safety</li>')
if g and not f.is_syntactic_guarantee():

7
spot/tl/hierarchy.cc
View file

@ -66,8 +66,11 @@ namespace spot
auto min = minimize_obligation(aut, f);
if (aut != min) // An obligation.
{
bool g = is_terminal_automaton(min);
bool s = is_safety_mwdba(min);
scc_info si(min);
// The minimba WDBA can have some trivial accepting SCCs
// that we should ignore in is_terminal_automaton().
bool g = is_terminal_automaton(min, &si, true);
bool s = is_safety_automaton(min, &si);
if (g)
return s ? 'B' : 'G';
else

25
spot/twaalgos/minimize.cc
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016 Laboratoire de
// Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Laboratoire de
// Recherche et Développement de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -520,7 +520,7 @@ namespace spot
// (i.e., it is not the start of any accepting word).
scc_info sm(det_a);
sm.determine_unknown_acceptance();
unsigned scc_count = sm.scc_count();
// SCC that have been marked as useless.
std::vector<bool> useless(scc_count);
@ -539,18 +539,13 @@ namespace spot
bool transient = sm.is_trivial(m);
auto& succ = sm.succ(m);
if (transient && succ.empty())
{
// A trivial SCC without successor is useless.
useless[m] = true;
d[m] = k - 1;
continue;
}
// Compute the minimum color l of the successors.
// Also SCCs are useless if all their successor are
// useless.
unsigned l = k;
// Compute the minimum color l of the successors. Also SCCs
// are useless if all their successor are useless. Note
// that Löding uses k-1 as level for non-final SCCs without
// successors but that seems bogus: using k+1 will make sure
// that a non-final SCCs without successor (i.e., a useless
// SCC) will be ignored in the computation of the level.
unsigned l = k + 1;
for (unsigned j: succ)
{
is_useless &= useless[j];
@ -575,6 +570,8 @@ namespace spot
}
else
{
if (succ.empty())
is_useless = true;
d[m] = (l - 1) | 1; // largest odd number inferior or equal
}
}

47
spot/twaalgos/strength.cc
View file

@ -1,6 +1,6 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2010, 2011, 2013, 2014, 2015, 2016 Laboratoire de
// Recherche et Développement de l'Epita (LRDE)
// Copyright (C) 2010, 2011, 2013, 2014, 2015, 2016, 2017 Laboratoire
// de Recherche et Développement de l'Epita (LRDE)
//
// This file is part of Spot, a model checking library.
//
@ -28,7 +28,8 @@ namespace spot
namespace
{
template <bool terminal, bool inweak = false, bool set = false>
bool is_type_automaton(const twa_graph_ptr& aut, scc_info* si)
bool is_type_automaton(const twa_graph_ptr& aut, scc_info* si,
bool ignore_trivial_term = false)
{
// Create an scc_info if the user did not give one to us.
bool need_si = !si;
@ -89,7 +90,7 @@ namespace spot
// A terminal automaton should accept any word that as a prefix
// leading to an accepting edge. In other words, we cannot have
// an accepting edge that goes into a rejecting SCC.
if (terminal && is_term)
if (terminal && is_term && !ignore_trivial_term)
for (auto& e: aut->edges())
if (si->is_rejecting_scc(si->scc_of(e.dst))
&& aut->acc().accepting(e.acc))
@ -103,7 +104,12 @@ namespace spot
if (set)
{
if (terminal)
{
if (!ignore_trivial_term)
aut->prop_terminal(is_term && is_weak);
else if (is_term && is_weak)
aut->prop_terminal(true);
}
aut->prop_weak(is_weak);
aut->prop_very_weak(is_single_state_scc && is_weak);
if (inweak)
@ -116,13 +122,15 @@ namespace spot
}
bool
is_terminal_automaton(const const_twa_graph_ptr& aut, scc_info* si)
is_terminal_automaton(const const_twa_graph_ptr& aut, scc_info* si,
bool ignore_trivial_term)
{
trival v = aut->prop_terminal();
if (v.is_known())
return v.is_true();
bool res =
is_type_automaton<true>(std::const_pointer_cast<twa_graph>(aut), si);
is_type_automaton<true>(std::const_pointer_cast<twa_graph>(aut), si,
ignore_trivial_term);
std::const_pointer_cast<twa_graph>(aut)->prop_terminal(res);
return res;
}
@ -170,16 +178,27 @@ namespace spot
is_type_automaton<true, true, true>(aut, si);
}
bool is_safety_mwdba(const const_twa_graph_ptr& aut)
bool is_safety_automaton(const const_twa_graph_ptr& aut, scc_info* si)
{
if (!(aut->acc().is_buchi() || aut->acc().is_all()))
throw std::runtime_error
("is_safety_mwdba() should be called on a Buchi automaton");
for (auto& t: aut->edges())
if (!aut->acc().accepting(t.acc))
return false;
if (aut->acc().is_t())
return true;
bool need_si = !si;
if (need_si)
si = new scc_info(aut);
bool res = true;
unsigned scount = si->scc_count();
for (unsigned scc = 0; scc < scount; ++scc)
if (!si->is_trivial(scc) && si->is_rejecting_scc(scc))
{
res = false;
break;
}
if (need_si)
delete si;
return res;
}

27
spot/twaalgos/strength.hh
View file

@ -1,6 +1,6 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2010, 2011, 2013, 2014, 2015, 2016 Laboratoire de
// Recherche et Développement de l'Epita (LRDE)
// Copyright (C) 2010, 2011, 2013, 2014, 2015, 2016, 2017 Laboratoire
// de Recherche et Développement de l'Epita (LRDE)
//
// This file is part of Spot, a model checking library.
//
@ -29,6 +29,9 @@ namespace spot
/// are complete, and no accepting transitions lead to a
/// non-accepting SCC.
///
/// If ignore_trivial_scc is set, accepting transitions from trivial
/// SCCs are ignored.
///
/// This property guarantees that a word is accepted if it has some
/// prefix that reaches an accepting transition.
///
@ -41,8 +44,8 @@ namespace spot
/// the prop_terminal() property of the automaton as a side-effect,
/// so further calls will return in constant-time.
SPOT_API bool
is_terminal_automaton(const const_twa_graph_ptr& aut, scc_info* sm = nullptr);
is_terminal_automaton(const const_twa_graph_ptr& aut, scc_info* sm = nullptr,
bool ignore_trivial_scc = false);
/// \brief Check whether an automaton is weak.
///
@ -95,16 +98,22 @@ namespace spot
is_inherently_weak_automaton(const const_twa_graph_ptr& aut,
scc_info* sm = nullptr);
/// \brief Check whether a minimized WDBA represents a safety
/// property.
/// \brief Check whether an automaton is a safety automaton.
///
/// A safety automaton has only accepting SCCs (or trivial
/// SCCs).
///
/// A minimized WDBA (as returned by a successful run of
/// minimize_obligation()) represent safety property if it contains
/// only accepting transitions.
/// minimize_obligation()) represent safety property if it is a
/// safety automaton.
///
/// \param aut the automaton to check
///
/// \param sm an scc_info object for the automaton if available (it
/// will be built otherwise).
SPOT_API bool
is_safety_mwdba(const const_twa_graph_ptr& aut);
is_safety_automaton(const const_twa_graph_ptr& aut,
scc_info* sm = nullptr);
/// \brief Check whether an automaton is weak or terminal.
///

4
tests/core/hierarchy.test
View file

@ -62,3 +62,7 @@ cat >expected <<EOF
37 safety obligation persistence recurrence reactivity
EOF
diff out expected
test B = `ltlfilt --format=%h -f '(Gb R (b xor Gb)) W (a W Xa)'`
ltlfilt -q --safety --guarantee -f '(Gb R (b xor Gb)) W (a W Xa)'

7
tests/core/ikwiad.cc
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2007-2016 Laboratoire de Recherche et Développement
// Copyright (C) 2007-2017 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2003-2007 Laboratoire d'Informatique de Paris 6
// (LIP6), département Systèmes Répartis Coopératifs (SRC), Université
@ -1373,8 +1373,9 @@ checked_main(int argc, char** argv)
}
else
{
bool g = is_terminal_automaton(ensure_digraph(a));
bool s = is_safety_mwdba(ensure_digraph(a));
bool g = is_terminal_automaton(ensure_digraph(a),
nullptr, true);
bool s = is_safety_automaton(ensure_digraph(a));
if (g && !s)
{
std::cout << "this is a guarantee property (hence, "