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translate: add a new relabel-overlap option

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Fixes issue #536.  Also a part of issue #500.

* spot/twaalgos/translate.hh, spot/twaalgos/translate.cc: Implement
this new option.
* bin/spot-x.cc, NEWS: Mention it.
* tests/core/ltl2tgba2.test: Add the test case from issue #536.
This commit is contained in:
Alexandre Duret-Lutz 2023-08-28 22:45:44 +02:00
parent 18478e663f
commit 110b052b7d
5 changed files with 92 additions and 14 deletions
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23
NEWS
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@ -37,6 +37,29 @@ New in spot 2.11.6.dev (not yet released)
replace boolean subformulas by fresh atomic propositions even if
those subformulas share atomic propositions.
- spot::translate() has a new -x option "relabel-overlap=M" that
augments the existing "relabel-bool=N". By default, N=4, M=8.
When the formula to translate has more than N atomic propositions,
relabel_bse() is first called to attempt to rename non-overlaping
boolean subexpressions (i.e., no shared atomic proposition) in
order to reduce the number of atomic proposition, a source of
explonential explosion in several places of the translation
pipeline. This relabel-bool optimization exists since Spot 2.4.
The new feature is that if, after relabel-bool, the formula still
has more than M atomic propositions, then spot::translate() now
attempts to relabel boolean subexpressions even if they have
overlapping atomic propositions, in an attempt to reduce the
number of atomic proposition even more. Doing so has the slightly
unfortunate side effect of hindering some simplifications (because
the new atomic propositions hide their interactions), but it
usually incures a large speedup. (See Issue #500, Issue #536.)
For instance on Alexandre's laptop, running
'ltlsynt --tlsf SPIReadManag.tlsf --aiger'
with Spot 2.11.6 used to produce an AIG circuit with 48 nodes in
36 seconds; it now produce an AIG circuit with 53 nodes in only
0.1 second.
New in spot 2.11.6 (2023-08-01)
Bug fixes:

11
bin/spot-x.cc
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@ -196,7 +196,16 @@ disabled, it is just an upper bound otherwise.") },
with N atomic propositions or more will have its Boolean subformulas \
abstracted as atomic propositions during the translation to automaton. \
This relabeling can speeds the translation if a few Boolean subformulas \
use a large number of atomic propositions. By default N=4. Setting \
use a large number of atomic propositions. This relabeling make sure \
the subexpression that are replaced do not share atomic propositions. \
By default N=4. Setting this value to 0 will disable the rewriting.") },
{ DOC("relabel-overlap", "If set to a positive integer N, a formula \
with N atomic propositions or more will have its Boolean subformulas \
abstracted as atomic propositions during the translation to automaton. \
This version does not care about overlapping atomic propositions, so \
it can cause the created temporary automata to have incompatible \
combinations of atomic propositions that will be eventually be removed. \
This relabeling is attempted after relabel-bool. By default N=8. Setting \
this value to 0 will disable the rewriting.") },
{ DOC("wdba-minimize", "Set to 0 to disable WDBA-minimization, to 1 to \
always try it, or 2 to attempt it only on syntactic obligations or on automata \

44
spot/twaalgos/translate.cc
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@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2013-2018, 2020-2022 Laboratoire de Recherche et
// Copyright (C) 2013-2018, 2020-2023 Laboratoire de Recherche et
// Développement de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -38,6 +38,7 @@ namespace spot
{
comp_susp_ = early_susp_ = skel_wdba_ = skel_simul_ = 0;
relabel_bool_ = 4;
relabel_overlap_ = 8;
tls_impl_ = -1;
ltl_split_ = true;
exprop_ = -1;
@ -47,6 +48,7 @@ namespace spot
return;
relabel_bool_ = opt->get("relabel-bool", 4);
relabel_overlap_ = opt->get("relabel-overlap", 6);
comp_susp_ = opt->get("comp-susp", 0);
if (comp_susp_ == 1)
{
@ -480,15 +482,23 @@ namespace spot
// 2) has some Boolean subformula
// 3) relabel_bse() actually reduces the number of atomic
// propositions.
//
// If the formula still has more than relabel_overlap_ APs after
// the above, we try the more aggressive relabel_overlapping_bse()
// function. However after applying this function, we might have
// false edges.
relabeling_map m;
formula to_work_on = *f;
if (relabel_bool_ > 0)
if (relabel_bool_ > 0 || relabel_overlap_ > 0)
{
std::set<formula> aps;
atomic_prop_collect(to_work_on, &aps);
unsigned atomic_props = aps.size();
if (atomic_props >= (unsigned) relabel_bool_)
if ((relabel_bool_
&& atomic_props >= (unsigned) relabel_bool_)
|| (relabel_overlap_
&& atomic_props >= (unsigned) relabel_overlap_))
{
// Make a very quick simplification path before for
// Boolean subformulas, only only syntactic rules. This
@ -507,14 +517,15 @@ namespace spot
options.nenoform_stop_on_boolean = true;
options.boolean_to_isop = false;
tl_simplifier simpl(options, simpl_->get_dict());
to_work_on = simpl.simplify(to_work_on);
formula simplified = to_work_on = simpl.simplify(to_work_on);
// Do we have Boolean subformulas that are not atomic
// propositions?
bool has_boolean_sub = false;
to_work_on.traverse([&](const formula& f)
{
if (f.is_boolean())
if (f.is_boolean()
&& !f.is(op::ap, op::Not))
{
has_boolean_sub = true;
return true;
@ -523,14 +534,37 @@ namespace spot
});
if (has_boolean_sub)
{
if (relabel_bool_
&& atomic_props >= (unsigned) relabel_bool_)
{
formula relabeled = relabel_bse(to_work_on, Pnn, &m);
if (m.size() < atomic_props)
{
atomic_props = m.size();
to_work_on = relabeled;
}
else
{
m.clear();
}
}
if (relabel_overlap_
&& atomic_props >= (unsigned) relabel_overlap_)
{
relabeling_map m2;
formula relabeled =
relabel_overlapping_bse(simplified, Pnn, &m2);
if (m2.size() < atomic_props)
{
atomic_props = m2.size();
to_work_on = relabeled;
std::swap(m, m2);
}
m2.clear();
}
}
}
}
formula r = simpl_->simplify(to_work_on);

5
spot/twaalgos/translate.hh
View file

@ -1,6 +1,6 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2013-2018, 2020, 2022 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2013-2018, 2020, 2022, 2023 Laboratoire de Recherche
// et Développement de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
//
@ -150,6 +150,7 @@ namespace spot
int skel_wdba_;
int skel_simul_;
int relabel_bool_;
int relabel_overlap_;
int tls_impl_;
bool gf_guarantee_ = true;
bool gf_guarantee_set_ = false;

13
tests/core/ltl2tgba2.test
View file

@ -1,6 +1,6 @@
#!/bin/sh
# -*- coding: utf-8 -*-
# Copyright (C) 2009-2022 Laboratoire de Recherche et Développement de
# Copyright (C) 2009-2023 Laboratoire de Recherche et Développement de
# l'Epita (LRDE).
# Copyright (C) 2003, 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
# département Systèmes Répartis Coopératifs (SRC), Université Pierre
@ -516,3 +516,14 @@ f='G((a -> X((!a U b) | G!a)) & (a -> X(G!a | (!a U c))) & (a -> X(G!a
(a -> X(G!a | (!a U g))) & (a -> X(G!a | (!a U h)))) & (GFa <-> (GFb &
GFc & GFd & GFe & GFf & GFg & GFh))'
test 128 = `ltl2tgba -G -D "$f" --stats=%s`
# This used to die from out of memory after 5 minutes. See issue #536.
f='(TRUE & (G F ~v21)& (( G F v39 -> G F v23))) -> (TRUE &
(G F (v1 -> (v41 & v29)))& (G F (v3 -> (v42 & v29)))& (G F (v5
-> (v43 & v29)))& (G F (v7 -> (v44 & v29)))& (G F (v9 -> (v45 &
v29)))& (G F (v11 -> (v46 & v29)))& (G F (v13 -> (v47 & v29)))&
(G F (v15 -> (v48 & v29)))& (G F (v17 -> (v49 & v29)))& (G F (v19
-> (v50 & v29)))& (G F (v41 | (v1 | (v3 | (v5 | (v7 | (v9 |
(v11 | (v13 | (v15 | (v17 | v19))))))))))))'
ltl2tgba -p'min even' -D -C "$f" --stats='%s %e'>out
test '22 288' = "`cat out`"