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wdba_minimization: skip one inclusion test on deterministic input

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* spot/twaalgos/minimize.cc (wdba_minimization): Improve handling of
deterministic input by not doing the powerset/wdba_scc_is_accepting
duo, and skipping the one inclusion test.
This commit is contained in:
Alexandre Duret-Lutz 2017-11-10 22:07:30 +01:00
parent 43b580ccee
commit 32019b6e1a
1 changed files with 24 additions and 9 deletions
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31
spot/twaalgos/minimize.cc
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@ -473,6 +473,10 @@ namespace spot
{
power_map pm;
bool input_is_det = is_deterministic(a);
if (input_is_det)
det_a = std::const_pointer_cast<twa_graph>(a);
else
det_a = tgba_powerset(a, pm);
// For each SCC of the deterministic automaton, determine if it
@ -487,6 +491,8 @@ namespace spot
// (i.e., it is not the start of any accepting word).
scc_info sm(det_a);
if (input_is_det)
sm.determine_unknown_acceptance();
unsigned scc_count = sm.scc_count();
// SCC that have been marked as useless.
@ -529,8 +535,12 @@ namespace spot
{
// Regular SCCs are accepting if any of their loop
// corresponds to an accepted word in the original
// automaton.
if (wdba_scc_is_accepting(det_a, m, a, sm, pm))
// automaton. If the automaton is the same as det_a, we
// can simply ask that to sm.
bool acc_scc = input_is_det
? sm.is_accepting_scc(m)
: wdba_scc_is_accepting(det_a, m, a, sm, pm);
if (acc_scc)
{
is_useless = false;
d[m] = l & ~1; // largest even number inferior or equal
@ -637,15 +647,20 @@ namespace spot
bool ok = false;
// Make sure the minimized WDBA does not accept more words than
// the input.
if (product(min_aut_f, aut_neg_f)->is_empty())
{
// Complement the minimized WDBA.
assert((bool)min_aut_f->prop_weak());
auto neg_min_aut_f = remove_fin(dualize(min_aut_f));
if (product(aut_f, neg_min_aut_f)->is_empty())
// Finally, we are now sure that it was safe
// to minimize the automaton.
ok = true;
// If the input was deterministic, then by construction
// min_aut_f accepts at least all the words of aut_f, so we do
// not need the reverse check. Otherwise, complement the
// minimized WDBA to test the reverse inclusion.
// (remove_fin() has a special handling of weak automata, and
// dualize also has a special handling of deterministic
// automata, so all these steps are quite efficient.)
ok = is_deterministic(aut_f)
|| product(aut_f, remove_fin(dualize(min_aut_f)))->is_empty();
}
if (ok)