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simulation: fix commit 8959eabad

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* spot/twaalgos/simulation.cc: Restrict common_in marks to current SCC
when pushing them, otherwise weak automata might become inherently
weak.
* tests/core/sim3.test: Add test case.
This commit is contained in:
Alexandre Duret-Lutz 2019-04-07 15:26:15 +02:00
parent 8c4f93d6c9
commit 4bb4aeb372
2 changed files with 126 additions and 36 deletions
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89
spot/twaalgos/simulation.cc
View file

@ -233,29 +233,26 @@ namespace spot
// common_out[i] is the set of acceptance set numbers common to
// all outgoing edges of state i.
std::vector<acc_cond::mark_t> common_out(ns);
scc_info si(a_, scc_info_options::NONE);
for (unsigned s = 0; s < ns; ++s)
{
bool first = true;
for (auto& e : a_->out(s))
{
if (first)
{
common_out[s] = e.acc;
first = false;
}
else if (common_out[s] != e.acc)
{
// If the automaton does not have
// state-based acceptance, do not change
// pull the marks. Mark the input as
// "not-state-acc" so that we remember
// that.
std::const_pointer_cast<twa_graph>(in)
->prop_state_acc(false);
goto donotpull;
}
}
if (first)
{
common_out[s] = e.acc;
first = false;
}
else if (common_out[s] != e.acc)
{
// If the automaton does not have
// state-based acceptance, do not change
// pull the marks. Mark the input as
// "not-state-acc" so that we remember
// that.
std::const_pointer_cast<twa_graph>(in)
->prop_state_acc(false);
goto donotpull;
}
}
// Pull the common outgoing sets to the incoming
// edges. Doing so seems to favor cases where states
@ -654,23 +651,6 @@ namespace spot
t.acc = acc;
}
}
if (!Sba && !Cosimulation && original_->prop_state_acc()
&& !record_implications_)
{
// common_in[i] is the set of acceptance set numbers
// common to all incoming edges of state i.
std::vector<acc_cond::mark_t>
common_in(res->num_states(), res->acc().all_sets());
for (auto& e : res->edges())
common_in[e.dst] &= e.acc;
// Push the common incoming sets to the outgoing edges.
// Doing so cancels the preprocessing we did in the other
// direction, to prevent marks from moving around the
// automaton if we apply simulation several times, and to
// favor state-based acceptance.
for (auto& e : res->edges())
e.acc = (e.acc - common_in[e.dst]) | common_in[e.src];
}
// If we recorded implications for the determinization
// procedure, we should not remove unreachable states, as that
@ -680,6 +660,43 @@ namespace spot
if (!record_implications_)
res->purge_unreachable_states();
// Push the common incoming sets to the outgoing edges.
// Doing so cancels the preprocessing we did in the other
// direction, to prevent marks from moving around the
// automaton if we apply simulation several times, and to
// favor state-based acceptance.
if (!Sba && !Cosimulation && !record_implications_
&& original_->prop_state_acc())
{
// common_in[i] is the set of acceptance set numbers
// common to all incoming edges of state i. Only edges
// inside one SCC matter.
unsigned ns = res->num_states();
std::vector<acc_cond::mark_t> common_in(ns);
scc_info si(res, scc_info_options::NONE);
for (unsigned s = 0; s < ns; ++s)
{
unsigned s_scc = si.scc_of(s);
bool first = true;
for (auto& e: res->out(s))
{
if (si.scc_of(e.dst) != s_scc)
continue;
if (first)
{
common_in[s] = e.acc;
first = false;
}
else
{
common_in[s] &= e.acc;
}
}
}
for (auto& e : res->edges())
e.acc = (e.acc - common_in[e.dst]) | common_in[e.src];
}
delete gb;
res->prop_copy(original_,
{ false, // state-based acc forced below

73
tests/core/sim3.test
View file

@ -86,3 +86,76 @@ State: 4 {0}
--END--
EOF
diff out expected
# This is a case where the "pull-mark in simulation" optimization
# introduced by 8959eabad caused the output automaton to be declared
# weak although it was only inherently weak.
cat >input <<EOF
HOA: v1
States: 8
Start: 0
AP: 2 "p0" "p1"
acc-name: Buchi
Acceptance: 1 Inf(0)
properties: trans-labels explicit-labels state-acc weak
--BODY--
State: 0
[0&1] 1
State: 1
[1] 2
[!0&1] 3
State: 2
[!0&1] 5
[0&1] 7
State: 3
[0&1] 4
[1] 5
State: 4 {0}
[0&1] 4
[1] 5
[!0&!1] 6
State: 5 {0}
[0&1] 4
[1] 5
State: 6 {0}
[!0&!1] 6
State: 7
[!0&1] 5
[!0&!1] 6
[0&1] 7
--END--
EOF
cat >expect <<EOF
HOA: v1
States: 7
Start: 0
AP: 2 "p0" "p1"
acc-name: Buchi
Acceptance: 1 Inf(0)
properties: trans-labels explicit-labels state-acc deterministic weak
--BODY--
State: 0
[0&1] 1
State: 1
[0&1] 2
[!0&1] 3
State: 2
[!0&1] 3
[0&1] 6
State: 3 {0}
[!0&1] 3
[0&1] 4
State: 4 {0}
[!0&1] 3
[0&1] 4
[!0&!1] 5
State: 5 {0}
[!0&!1] 5
State: 6
[!0&1] 3
[!0&!1] 5
[0&1] 6
--END--
EOF
autfilt --small --low input > output
diff expect output