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Rewrite the check of WDBA state acceptance in minimize().

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* src/tgbaalgos/powerset.hh (power_map): New structure, allowing
the caller to retrieve the set of original states corresponding to
the set in the deterministic automaton.
(power_set): Adjust prototype to take a power_map instead of the
acc_list.
* src/tgbaalgos/powerset.cc (power_set): Strip all code using
acc_list, and update power_set.
* src/tgbaalgos/minimize.cc (minimize): Rewrite, using an
algorithm similar to the one in the Dax paper to check whether
state of the minimized automaton should be accepting.
This commit is contained in:
Alexandre Duret-Lutz 2011-01-04 19:13:44 +01:00
parent 37a8d1dc92
commit 358d4bfdf2
4 changed files with 250 additions and 71 deletions
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72
src/tgbaalgos/powerset.cc
View file

@ -1,4 +1,4 @@
// Copyright (C) 2009, 2010 Laboratoire de Recherche et Développement
// Copyright (C) 2009, 2010, 2011 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
@ -22,46 +22,33 @@
// 02111-1307, USA.
#include <set>
#include <map>
#include <deque>
#include "powerset.hh"
#include "misc/hash.hh"
#include "tgbaalgos/powerset.hh"
#include "tgbaalgos/scc.hh"
#include "bdd.h"
namespace spot
{
tgba_explicit*
tgba_powerset(const tgba* aut,
std::list<const state*>* acc_list)
tgba_explicit_number*
tgba_powerset(const tgba* aut, power_map& pm)
{
typedef Sgi::hash_set<const state*, state_ptr_hash,
state_ptr_equal> state_set;
typedef std::set<const state*, state_ptr_less_than> power_state;
typedef std::map<power_state, int> power_set;
typedef std::deque<power_state> todo_list;
typedef power_map::power_state power_state;
typedef std::map<power_map::power_state, int> power_set;
typedef std::deque<power_map::power_state> todo_list;
power_set seen;
todo_list todo;
scc_map m(aut);
tgba_explicit_number* res = new tgba_explicit_number(aut->get_dict());
state_set states;
{
power_state ps;
state* s = aut->get_init_state();
states.insert(s);
pm.states.insert(s);
ps.insert(s);
todo.push_back(ps);
seen[ps] = 1;
if (acc_list)
{
m.build_map();
if (m.accepting(m.scc_of_state(s)))
acc_list->push_front(new state_explicit(res->add_state(1)));
}
pm.map_[1] = ps;
}
unsigned state_num = 1;
@ -86,30 +73,13 @@ namespace spot
// Construct the set of all states reachable via COND.
power_state dest;
bool accepting = false;
for (i = src.begin(); i != src.end(); ++i)
{
tgba_succ_iterator *si = aut->succ_iter(*i);
for (si->first(); !si->done(); si->next())
if ((cond >> si->current_condition()) == bddtrue)
{
const state* s = si->current_state();
state_set::const_iterator i = states.find(s);
if (i != states.end())
{
delete s;
s = *i;
}
else
{
states.insert(s);
}
if (acc_list)
{
unsigned scc_num = m.scc_of_state(s);
if (m.accepting(scc_num))
accepting = true;
}
const state* s = pm.canonicalize(si->current_state());
dest.insert(s);
}
delete si;
@ -129,29 +99,21 @@ namespace spot
{
dest_num = ++state_num;
seen[dest] = dest_num;
pm.map_[dest_num] = dest;
todo.push_back(dest);
t = res->create_transition(seen[src], dest_num);
if (accepting)
{
const state* dst = new state_explicit(t->dest);
acc_list->push_front(dst);
}
}
res->add_conditions(t, cond);
}
}
res->merge_transitions();
// Release all states.
state_set::const_iterator i = states.begin();
while (i != states.end())
{
// Advance the iterator before deleting the key.
const state* s = *i;
++i;
delete s;
}
return res;
}
tgba_explicit_number*
tgba_powerset(const tgba* aut)
{
power_map pm;
return tgba_powerset(aut, pm);
}
}