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degen: Improve when initial state is accepting without self-loop.

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* src/tgbaalgos/degen.cc: Choose the initial level according
to acceptance condition common to all outgoing transitions.
* src/tgbatest/degenid.test: Add test case.
* NEWS: Mention it.
This commit is contained in:
Alexandre Duret-Lutz 2013-08-23 13:23:59 +02:00
parent 67a4833576
commit dfc5ff95e5
3 changed files with 51 additions and 8 deletions
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25
src/tgbaalgos/degen.cc
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@ -188,8 +188,7 @@ namespace spot
acc = temp;
unsigned next = slevel;
while (next < order_.size()
&& (acc & order_[next]) == order_[next])
while (next < order_.size() && bdd_implies(order_[next], acc))
++next;
return next;
}
@ -314,8 +313,8 @@ namespace spot
const state* s0 = uniq(a->get_init_state());
degen_state s(s0, 0);
// As an heuristic, if the initial state has accepting self-loops,
// start the degeneralization on the accepting level.
// As an heuristic, if the initial state at least one accepting
// self-loop, start the degeneralization on the accepting level.
{
bdd all = a->all_acceptance_conditions();
tgba_succ_iterator* it = a->succ_iter(s0);
@ -335,6 +334,18 @@ namespace spot
}
delete it;
}
// Otherwise, check for acceptance conditions common to all
// outgoing transitions, and assume we have already seen these and
// start on the associated level.
if (s.second == 0)
{
bdd acc = outgoing.common_acc(s.first);
if (use_cust_acc_orders)
s.second = orders.next_level(m.initial(), s.second, acc);
else
while (s.second < order.size() && bdd_implies(order[s.second], acc))
++s.second;
}
#ifdef DEGEN_DEBUG
std::map<const state*, int>names;
@ -426,7 +437,7 @@ namespace spot
// 1=>1, 1=>2, 2->2, 2->1 This is already an SBA,
// with 1 as accepting state. However if you try
// degeralize it without ignoring *prev, you'll get
// two copies of states 2, depending on whether we
// two copies of state 2, depending on whether we
// reach it using 1=>2 or from 2->2. If this
// example was not clear, uncomment the following
// "if" block, and play with the "degenid.test"
@ -485,7 +496,7 @@ namespace spot
}
else
{
// If using custom acc orders, get next level for this scc
// If using custom acc orders, get next level for this scc
if (use_cust_acc_orders)
d.second = orders.next_level(scc, next, acc);
// Else compute level according the global acc order
@ -495,7 +506,7 @@ namespace spot
// acceptance sets common to the outgoing transitions of
// the destination state.
while (next < order.size()
&& (acc & order[next]) == order[next])
&& bdd_implies(order[next], acc))
++next;
d.second = next;