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Make sure the degeneralization is idempotent (up to renaming of

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states).

* src/tgbaalgos/tgbatba.cc: When degeneralizing to SBA, remove the
acceptance conditions that are common to all outgoing transitions
of this state.  This helps to make the degeneralization
idempotent.
* src/tgbatest/degenid.test: New test case.
* src/tgbatest/Makefile.am: Add it.
This commit is contained in:
Alexandre Duret-Lutz 2011-08-25 18:42:00 +02:00
parent bf7b94e1cd
commit bc416fdb2f
4 changed files with 83 additions and 8 deletions
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38
src/tgba/tgbatba.cc
View file

@ -143,7 +143,8 @@ namespace spot
typedef tgba_tba_proxy::cycle_list list;
typedef tgba_tba_proxy::cycle_list::const_iterator iterator;
public:
tgba_tba_proxy_succ_iterator(tgba_succ_iterator* it,
tgba_tba_proxy_succ_iterator(const state* rs,
tgba_succ_iterator* it,
iterator expected,
const list& cycle,
bdd the_acceptance_cond,
@ -156,10 +157,11 @@ namespace spot
bdd acc = it->current_acceptance_conditions();
// As an extra optimization step, gather the acceptance
// conditions common to all outgoing transitions of the
// destination state, and pretend they are already present
// on this transition.
// destination state. We will later add these to "acc" to
// pretend they are already present on this transition.
state* odest = it->current_state();
acc |= aut->common_acceptance_conditions_of_original_state(odest);
bdd otheracc =
aut->common_acceptance_conditions_of_original_state(odest);
iterator next;
// bddtrue is a special condition used for tgba_sba_proxy
@ -169,7 +171,22 @@ namespace spot
// bddtrue is also used by tgba_tba_proxy if the automaton
// does not use acceptance conditions. In that case, all
// states are accepting.
if (*expected != bddtrue)
if (*expected == bddtrue)
{
// When degeneralizing to SBA, remove the acceptance
// conditions that are common to all outgoing
// transitions of this state. Since they are common,
// we need not fear removing them: we will see them
// eventually if we make a cycle. This helps to make
// the degeneralization idempotent.
acc -= aut->common_acceptance_conditions_of_original_state(rs);
// Use the acceptance sets common to all outgoing
// transition of the destination state. In case of a
// self-loop, we will be adding back the acceptance
// sets we removed. This is what we want.
acc |= otheracc;
}
else
{
// A transition in the *EXPECTED acceptance set should
// be directed to the next acceptance set. If the
@ -189,6 +206,10 @@ namespace spot
// month = {December}
// }
next = expected;
// Consider both the current acceptance sets, and the
// acceptance sets common to the outgoing transition of
// the destination state.
acc |= otheracc;
while (next != cycle.end() && (acc & *next) == *next)
++next;
if (next != cycle.end())
@ -367,10 +388,11 @@ namespace spot
down_cast<const state_tba_proxy*>(local_state);
assert(s);
tgba_succ_iterator* it = a_->succ_iter(s->real_state(),
global_state, global_automaton);
const state* rs = s->real_state();
tgba_succ_iterator* it = a_->succ_iter(rs, global_state, global_automaton);
return new tgba_tba_proxy_succ_iterator(it, s->acceptance_iterator(),
return new tgba_tba_proxy_succ_iterator(rs, it,
s->acceptance_iterator(),
acc_cycle_, the_acceptance_cond_,
this);
}