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translate: add a branch-post option

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* spot/twaalgos/translate.cc, spot/twaalgos/translate.hh: Here.
* NEWS, bin/spot-x.cc: Mention it.
* tests/core/genltl.test: Test it.
This commit is contained in:
Alexandre Duret-Lutz 2022-09-22 15:44:18 +02:00
parent 7ed62f7eed
commit 3729dfad90
5 changed files with 29 additions and 4 deletions
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5
NEWS
View file

@ -159,6 +159,11 @@ New in spot 2.10.6.dev (not yet released)
further simplification. This was introduced to help with automata
produced from formulas output by "genltl --eil-gsi" (see above).
- spot::postproc has new configuration variable branch-post that
can be used to control the use of branching-postponement (diabled
by default) or delayed-branching (see above, enabled by default).
See the spot-x(7) man page for details.
- spot::parallel_policy is an object that can be passed to some
algorithm to specify how many threads can be used if Spot has been
compiled with --enable-pthread. Currently, only

5
bin/spot-x.cc
View file

@ -50,6 +50,11 @@ implication checks for formula simplifications. Defaults to 64.") },
{ nullptr, 0, nullptr, 0, "Translation options:", 0 },
{ DOC("ltl-split", "Set to 0 to disable the translation of automata \
as product or sum of subformulas.") },
{ DOC("branch-prop", "Set to 0 to disable branching-postponement \
(done during translation, may create more states) and delayed-branching \
(almost similar, but done after translation to only remove states). \
Set to 1 to force branching-postponement, and to 2 \
to force delayed-branching. By default delayed-branching is used.") },
{ DOC("comp-susp", "Set to 1 to enable compositional suspension, \
as described in our SPIN'13 paper (see Bibliography below). Set to 2, \
to build only the skeleton TGBA without composing it. Set to 0 (the \

13
spot/twaalgos/translate.cc
View file

@ -65,6 +65,7 @@ namespace spot
int tls_max_states = opt->get("tls-max-states", 64);
tls_max_states_ = std::max(0, tls_max_states);
exprop_ = opt->get("exprop", -1);
branchpost_ = opt->get("branch-post", -1);
}
void translator::build_simplifier(const bdd_dict_ptr& dict)
@ -399,10 +400,18 @@ namespace spot
bool exprop = unambiguous
|| (level_ == postprocessor::High && exprop_ != 0)
|| exprop_ > 0;
// branch-post: 1 == force branching postponement
// 0 == disable branching post. and delay_branching
// 2 == force delay_branching
// -1 == auto (delay_branching)
// Some quick experiments suggests that branching postponement
// can produce larger automata on non-obligations formulas, and
// that even on obligation formulas, delay_branching is faster.
bool bpost = branchpost_ == 1;
aut = ltl_to_tgba_fm(r, simpl_->get_dict(), exprop,
true, false, false, nullptr, nullptr,
true, bpost, false, nullptr, nullptr,
unambiguous);
if (delay_branching_here(aut))
if (!bpost && branchpost_ != 0 && delay_branching_here(aut))
{
aut->purge_unreachable_states();
aut->merge_edges();

3
spot/twaalgos/translate.hh
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2013-2018, 2020 Laboratoire de Recherche et Développement
// Copyright (C) 2013-2018, 2020, 2022 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -154,6 +154,7 @@ namespace spot
bool gf_guarantee_ = true;
bool gf_guarantee_set_ = false;
bool ltl_split_;
int branchpost_ = -1;
unsigned tls_max_states_ = 0;
int exprop_;
const option_map* opt_;

7
tests/core/genltl.test
View file

@ -280,7 +280,8 @@ diff range1.ltl range2.ltl
# I introduced delay_branching_here(), a cheap function that is called
# before simplification. In this case, this is enough to determinize
# the automaton, simplifying simulation-based reduction greatly.
genltl --eil-gsi=1..25 | ltlfilt --from-ltlf | ltl2tgba --stats=%s,%e >output
genltl --eil-gsi=1..25 | ltlfilt --from-ltlf > formulas.ltl
ltl2tgba -F formulas.ltl --stats=%s,%e >output
cat >expected <<EOF
5,9
7,15
@ -309,3 +310,7 @@ cat >expected <<EOF
53,153
EOF
diff expected output
# branching postponement should work as well
ltl2tgba -F formulas.ltl -x branch-post=1 --stats=%s,%e >output
diff expected output