Commit df1bf80d authored by Alexandre Duret-Lutz's avatar Alexandre Duret-Lutz
Browse files

* src/tgbaalgos/gv04.cc (gv04::result): New struct to compute

counter examples.
(gv04:check): Return a gv04::result.
parent 976a86ba
2004-11-23 Poitrenaud Denis <Denis.Poitrenaud@lip6.fr>
2004-11-23 Alexandre Duret-Lutz <adl@src.lip6.fr>
* src/tgbaalgos/gv04.cc (gv04::result): New struct to compute
counter examples.
(gv04:check): Return a gv04::result.
2004-11-23 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/tau03opt.cc: Fix a warning.
......@@ -25,7 +31,7 @@
new algorithm.
* src/tgbatest/emptchk.test: Test it.
2004-11-22 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-22 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/emptiness_stats.hh, src/tgbaalgos/weight.cc,
src/tgbaalgos/weight.hh: New files.
......@@ -53,7 +59,7 @@
* src/tgbatest/randtgba.cc (main): Add options -z and -Z for statistics.
(ce_stat): New struct.
2004-11-17 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-17 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/se05.hh, src/tgbaalgos/tau03.hh: Typo.
* src/tgbaalgos/tau03.cc: Suppress optimisations, the algorithm is now
......@@ -81,7 +87,7 @@
src/misc/random.hh, src/misc/version.hh, src/tgba/state.hh: More
Doxygen groups.
2004-11-17 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-17 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/magic.hh: Fix a comment and remove se05 interface.
* src/tgbaalgos/magic.cc: Fix a comment.
......@@ -187,7 +193,7 @@
of randtgba.
* src/tgbatest/emptchk.test: Adjust.
2004-11-15 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-15 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/magic.cc: Fix a stupid bug.
* src/tgbaalgos/se05.cc: Fix the same bug.
......@@ -209,7 +215,7 @@
* src/tgbaalgos/replayrun.cc (replay_tgba_run): Write to the
supplied stream, not std::cout.
2004-11-15 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-15 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/magic.cc: Add a bit state hashing version.
* src/tgbaalgos/se05.cc: Add a bit state hashing version.
......@@ -269,7 +275,7 @@
* src/tgbatest/ltl2tgba.cc (syntax): Fix old typos and reword
some help strings.
2004-11-09 Poitrenaud Denis <denis@src.lip6.fr>
2004-11-09 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/tgbaalgos/magic.cc: rewrite to externalize the heap and
prepare it to a bit state hashing version.
......@@ -1462,7 +1468,7 @@
* wrap/python/spot.i: Process tgbaalgos/neverclaim.hh.
* wrap/python/cgi/ltl2tgba.in: Display the never claim on demand.
2004-04-21 Denis Poitrenaud <dp@src.lip6.fr>
2004-04-21 Denis Poitrenaud <Denis.Poitrenaud@lip6.fr>
* src/ltlvisit/tostring.hh (to_spin_string): New function.
Convert a formula into a string parsable by Spin.
......
......@@ -30,6 +30,8 @@
#include <cassert>
#include <utility>
#include <map>
#include <deque>
#include "tgba/tgba.hh"
#include "misc/hash.hh"
#include "emptiness.hh"
......@@ -43,10 +45,7 @@ namespace spot
struct stack_entry
{
const state* s; // State stored in stack entry.
tgba_succ_iterator* nexttr; // Next transition to explore.
// (The paper uses lasttr for the
// last transition, but nexttr is
// easier for our iterators.)
tgba_succ_iterator* lasttr; // Last transition explored from this state.
int lowlink; // Lowlink value if this entry.
int pre; // DFS predecessor.
int acc; // Accepting state link.
......@@ -83,7 +82,7 @@ namespace spot
~gv04()
{
for (stack_type::iterator i = stack.begin(); i != stack.end(); ++i)
delete i->nexttr;
delete i->lasttr;
hash_type::const_iterator s = h.begin();
while (s != h.end())
{
......@@ -103,13 +102,22 @@ namespace spot
while (!violation && dftop >= 0)
{
tgba_succ_iterator* iter = stack[dftop].nexttr;
trace << "Main iteration (top = " << top
<< ", dftop = " << dftop
<< ", s = " << a->format_state(stack[dftop].s)
<< ")" << std::endl;
tgba_succ_iterator* iter = stack[dftop].lasttr;
if (!iter)
{
iter = stack[dftop].lasttr = a->succ_iter(stack[dftop].s);
iter->first();
}
else
{
iter->next();
}
if (iter->done())
{
trace << " No more successors" << std::endl;
......@@ -119,7 +127,6 @@ namespace spot
{
const state* s_prime = iter->current_state();
bool acc = iter->current_acceptance_conditions() == accepting;
iter->next();
inc_transitions();
trace << " Next successor: s_prime = "
......@@ -156,7 +163,7 @@ namespace spot
set_states(h.size());
}
if (violation)
return new emptiness_check_result;
return new result(*this);
return 0;
}
......@@ -168,9 +175,7 @@ namespace spot
h[s] = ++top;
tgba_succ_iterator* iter = a->succ_iter(s);
iter->first();
stack_entry ss = { s, iter, top, dftop, 0 };
stack_entry ss = { s, 0, top, dftop, 0 };
if (accepting)
ss.acc = dftop; // This differs from GV04 to support TBA.
......@@ -199,7 +204,7 @@ namespace spot
assert(static_cast<unsigned int>(top + 1) == stack.size());
for (int i = top; i >= dftop; --i)
{
delete stack[i].nexttr;
delete stack[i].lasttr;
stack.pop_back();
dec_depth();
}
......@@ -235,6 +240,235 @@ namespace spot
return os;
}
struct result: public emptiness_check_result
{
result(gv04& data)
: data(data)
{
}
virtual tgba_run*
accepting_run()
{
tgba_run* res = new tgba_run;
// Transitively update the lowlinks, so we can use them in
// the BDS bellow.
for (int i = 0; i <= data.top; ++i)
{
int l = data.stack[i].lowlink;
if (l < i)
{
int ll = data.stack[i].lowlink = data.stack[l].lowlink;
for (int j = i - 1; data.stack[j].lowlink != ll; --j)
data.stack[j].lowlink = ll;
}
}
#ifdef TRACE
for (int i = 0; i <= data.top; ++i)
{
trace << "state " << i << " ("
<< data.a->format_state(data.stack[i].s)
<< ") has lowlink = " << data.stack[i].lowlink << std::endl;
}
#endif
// We will use the root of the last SCC as the start of the
// cycle.
int scc_root = data.stack[data.dftop].lowlink;
assert(scc_root >= 0);
// Construct the prefix by unwinding the DFS stack before
// scc_root.
int father = data.stack[scc_root].pre;
while (father >= 0)
{
tgba_run::step st =
{
data.stack[father].s->clone(),
data.stack[father].lasttr->current_condition(),
data.stack[father].lasttr->current_acceptance_conditions()
};
res->prefix.push_front(st);
father = data.stack[father].pre;
}
// Construct the cycle in two phases. A first BFS find the
// shortest path from scc_root to an accepting transition.
// A second BFS then search a path back to scc_root. If
// there is no acceptance conditions we just use the second
// BFS to find a cycle around scc_root.
const state* bfs_start = data.stack[scc_root].s;
const state* bfs_end = bfs_start;
if (data.accepting != bddfalse)
{
trace << "1st BFS" << std::endl;
// Records backlinks to parent state during the BFS.
// (This also stores the propositions of this link.)
std::map<const state*, tgba_run::step,
state_ptr_less_than> father;
// BFS queue.
std::deque<const state*> todo;
// Initial state.
todo.push_back(bfs_start);
while (!todo.empty())
{
const state* src = todo.front();
todo.pop_front();
tgba_succ_iterator* i = data.a->succ_iter(src);
for (i->first(); !i->done(); i->next())
{
const state* dest = i->current_state();
trace << " state " << data.a->format_state(dest);
// Do not escape the SCC
hash_type::const_iterator j = data.h.find(dest);
if (// This state was never visited so far.
j == data.h.end()
// Or it was discarded
|| j->second >= data.stack.size()
// Or it was discarded (but its stack slot reused)
|| data.stack[j->second].s->compare(dest)
// Or it is still on the stack but not in the SCC
|| data.stack[j->second].lowlink < scc_root)
{
trace << " ignored" << std::endl;
delete dest;
continue;
}
trace << " explored" << std::endl;
delete dest;
dest = j->first;
bdd cond = i->current_condition();
bdd acc = i->current_acceptance_conditions();
tgba_run::step s = { src, cond, acc };
if (acc != bddfalse)
{
// Found it!
tgba_run::steps p;
while (s.s != bfs_start)
{
p.push_front(s);
s = father[s.s];
}
p.push_front(s);
res->cycle.splice(res->cycle.end(), p);
// Exit this BFS, and start the next one at dest.
todo.clear();
bfs_start = dest;
break;
}
// Common case: record backlinks and continue BFS
// for unvisited states.
if (father.find(dest) == father.end())
{
todo.push_back(dest);
father[dest] = s;
}
}
delete i;
}
}
// Second BFS.
if (bfs_start != bfs_end || res->cycle.empty())
{
trace << "2nd BFS" << std::endl;
// Records backlinks to parent state during the BFS.
// (This also stores the propositions of this link.)
std::map<const state*, tgba_run::step,
state_ptr_less_than> father;
// BFS queue.
std::deque<const state*> todo;
// Initial state.
todo.push_back(bfs_start);
while (!todo.empty())
{
const state* src = todo.front();
todo.pop_front();
tgba_succ_iterator* i = data.a->succ_iter(src);
for (i->first(); !i->done(); i->next())
{
const state* dest = i->current_state();
trace << " state " << data.a->format_state(dest);
// Do not escape the SCC
hash_type::const_iterator j = data.h.find(dest);
if (// This state was never visited so far.
j == data.h.end()
// Or it was discarded
|| j->second >= data.stack.size()
// Or it was discarded (but its stack slot reused)
|| data.stack[j->second].s->compare(dest)
// Or it is still on the stack but not in the SCC
|| data.stack[j->second].lowlink < scc_root)
{
trace << " ignored" << std::endl;
delete dest;
continue;
}
trace << " explored" << std::endl;
delete dest;
dest = j->first;
bdd cond = i->current_condition();
bdd acc = i->current_acceptance_conditions();
tgba_run::step s = { src, cond, acc };
if (dest == bfs_end)
{
// Found it!
tgba_run::steps p;
while (s.s != bfs_start)
{
p.push_front(s);
s = father[s.s];
}
p.push_front(s);
res->cycle.splice(res->cycle.end(), p);
// Exit this BFS.
todo.clear();
break;
}
// Common case: record backlinks and continue BFS
// for unvisited states.
if (father.find(dest) == father.end())
{
todo.push_back(dest);
father[dest] = s;
}
}
delete i;
}
}
// Clone every state in the cycle before returning it. (We
// didn't do that before in the algorithm, because it's
// easier to follow if every state manipulated in the BFS is
// the instance in the hash table.)
for (tgba_run::steps::iterator i = res->cycle.begin();
i != res->cycle.end(); ++i)
i->s = i->s->clone();
assert(res->cycle.begin() != res->cycle.end());
return res;
}
gv04& data;
};
};
} // anonymous
......
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