tgba2ta.cc 20.4 KB
Newer Older
1
// -*- coding utf-8 -*-
2
// Copyright (C) 2010, 2011, 2012, 2013 Laboratoire de Recherche et
3
// Développement de l'Epita (LRDE).
4
5
6
7
8
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
9
// the Free Software Foundation; either version 3 of the License, or
10
11
12
13
14
15
16
17
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
18
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
19

20
//#define TRACE
21
22
23
24
25
26
27
28

#include <iostream>
#ifdef TRACE
#define trace std::clog
#else
#define trace while (0) std::clog
#endif

29
30
31
#include "ltlast/atomic_prop.hh"
#include "ltlast/constant.hh"
#include "tgba/formula2bdd.hh"
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
32
#include "tgba/sba.hh"
33
34
35
36
37
38
39
40
41
#include "misc/bddop.hh"
#include <cassert>
#include "ltlvisit/tostring.hh"
#include <iostream>
#include "tgba/bddprint.hh"
#include "tgbaalgos/gtec/nsheap.hh"
#include <stack>
#include "tgba2ta.hh"
#include "taalgos/statessetbuilder.hh"
42
#include "ta/tgtaexplicit.hh"
43
44
45
46
47
48

using namespace std;

namespace spot
{

49
50
51
52
  namespace
  {
    typedef std::pair<spot::state*, tgba_succ_iterator*> pair_state_iter;

53
54
55
56
57
    static void
    transform_to_single_pass_automaton
    (ta_explicit* testing_automata,
     state_ta_explicit* artificial_livelock_acc_state = 0)
    {
58

59
60
61
62
      if (artificial_livelock_acc_state != 0)
	{
	  state_ta_explicit* artificial_livelock_acc_state_added =
            testing_automata->add_state(artificial_livelock_acc_state);
63

64
65
66
67
68
69
	  // unique artificial_livelock_acc_state
	  assert(artificial_livelock_acc_state_added
		 == artificial_livelock_acc_state);
	  artificial_livelock_acc_state->set_livelock_accepting_state(true);
	  artificial_livelock_acc_state->free_transitions();
	}
70

71
72
      ta::states_set_t states_set = testing_automata->get_states_set();
      ta::states_set_t::iterator it;
73

74
      state_ta_explicit::transitions* transitions_to_livelock_states =
75
76
        new state_ta_explicit::transitions;

77
78
79
      for (it = states_set.begin(); it != states_set.end(); ++it)
	{
	  state_ta_explicit* source = static_cast<state_ta_explicit*> (*it);
80

81
	  transitions_to_livelock_states->clear();
82

83
84
	  state_ta_explicit::transitions* trans = source->get_transitions();
	  state_ta_explicit::transitions::iterator it_trans;
85

86
87
88
89
	  if (trans != 0)
	    for (it_trans = trans->begin(); it_trans != trans->end();)
	      {
		state_ta_explicit* dest = (*it_trans)->dest;
90

91
		state_ta_explicit::transitions* dest_trans =
92
                  (dest)->get_transitions();
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
		bool dest_trans_empty = dest_trans == 0 || dest_trans->empty();

		//select transitions where a destination is a livelock state
		// which isn't a Buchi accepting state and has successors
		if (dest->is_livelock_accepting_state()
		    && (!dest->is_accepting_state()) && (!dest_trans_empty))
		  transitions_to_livelock_states->push_front(*it_trans);

		// optimization to have, after minimization, an unique
		// livelock state which has no successors
		if (dest->is_livelock_accepting_state() && (dest_trans_empty))
		  dest->set_accepting_state(false);

		++it_trans;
	      }

	  if (transitions_to_livelock_states != 0)
	    {
	      state_ta_explicit::transitions::iterator it_trans;

	      for (it_trans = transitions_to_livelock_states->begin();
		   it_trans != transitions_to_livelock_states->end();
		   ++it_trans)
		{
		  if (artificial_livelock_acc_state != 0)
		    {
		      testing_automata->create_transition
			(source,
			 (*it_trans)->condition,
			 (*it_trans)->acceptance_conditions,
			 artificial_livelock_acc_state, true);
		    }
		  else
		    {
		      testing_automata->create_transition
			(source,
			 (*it_trans)->condition,
			 (*it_trans)->acceptance_conditions,
			 ((*it_trans)->dest)->stuttering_reachable_livelock,
			 true);
		    }
		}
	    }
	}
      delete transitions_to_livelock_states;

      for (it = states_set.begin(); it != states_set.end(); ++it)
	{
	  state_ta_explicit* state = static_cast<state_ta_explicit*> (*it);
	  state_ta_explicit::transitions* state_trans =
143
            (state)->get_transitions();
144
	  bool state_trans_empty = state_trans == 0 || state_trans->empty();
145

146
147
148
149
	  if (state->is_livelock_accepting_state()
	      && (!state->is_accepting_state()) && (!state_trans_empty))
	    state->set_livelock_accepting_state(false);
	}
150
151
    }

152
153
154
155
156
    static void
    compute_livelock_acceptance_states(ta_explicit* testing_automata,
				       bool single_pass_emptiness_check,
				       state_ta_explicit*
				       artificial_livelock_acc_state)
157
    {
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
      // We use five main data in this algorithm:
      // * sscc: a stack of strongly stuttering-connected components (SSCC)
      scc_stack_ta sscc;

      // * arc, a stack of acceptance conditions between each of these SCC,
      std::stack<bdd> arc;

      // * h: a hash of all visited nodes, with their order,
      //   (it is called "Hash" in Couvreur's paper)
      numbered_state_heap* h =
	numbered_state_heap_hash_map_factory::instance()->build();
      ///< Heap of visited states.

      // * num: the number of visited nodes.  Used to set the order of each
      //   visited node,
      int num = 0;

      // * todo: the depth-first search stack.  This holds pairs of the
      //   form (STATE, ITERATOR) where ITERATOR is a tgba_succ_iterator
      //   over the successors of STATE.  In our use, ITERATOR should
      //   always be freed when TODO is popped, but STATE should not because
      //   it is also used as a key in H.
      std::stack<pair_state_iter> todo;

      // * init: the set of the depth-first search initial states
      std::stack<state*> init_set;

      ta::states_set_t::const_iterator it;
      ta::states_set_t init_states = testing_automata->get_initial_states_set();
      for (it = init_states.begin(); it != init_states.end(); ++it)
	{
	  state* init_state = (*it);
	  init_set.push(init_state);
	}

      while (!init_set.empty())
	{
	  // Setup depth-first search from initial states.

	  {
	    state_ta_explicit* init =
199
              down_cast<state_ta_explicit*> (init_set.top());
200
201
202
	    init_set.pop();
	    state_ta_explicit* init_clone = init;
	    numbered_state_heap::state_index_p h_init = h->find(init_clone);
203

204
205
	    if (h_init.first)
	      continue;
206

207
208
209
210
	    h->insert(init_clone, ++num);
	    sscc.push(num);
	    arc.push(bddfalse);
	    sscc.top().is_accepting
211
              = testing_automata->is_accepting_state(init);
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
	    tgba_succ_iterator* iter = testing_automata->succ_iter(init);
	    iter->first();
	    todo.push(pair_state_iter(init, iter));
	  }

	  while (!todo.empty())
	    {
	      state* curr = todo.top().first;

	      numbered_state_heap::state_index_p spi = h->find(curr);
	      // If we have reached a dead component, ignore it.
	      if (*spi.second == -1)
		{
		  todo.pop();
		  continue;
		}

	      // We are looking at the next successor in SUCC.
	      tgba_succ_iterator* succ = todo.top().second;

	      // If there is no more successor, backtrack.
	      if (succ->done())
		{
		  // We have explored all successors of state CURR.

		  // Backtrack TODO.
		  todo.pop();

		  // fill rem with any component removed,
		  numbered_state_heap::state_index_p spi = h->index(curr);
		  assert(spi.first);

		  sscc.rem().push_front(curr);

		  // When backtracking the root of an SSCC, we must also
		  // remove that SSCC from the ROOT stacks.  We must
		  // discard from H all reachable states from this SSCC.
		  assert(!sscc.empty());
		  if (sscc.top().index == *spi.second)
		    {
		      // removing states
		      std::list<state*>::iterator i;
		      bool is_livelock_accepting_sscc = (sscc.rem().size() > 1)
			&& ((sscc.top().is_accepting)
			    || (sscc.top().condition ==
				testing_automata->all_acceptance_conditions()));

		      trace << "*** sscc.size()  = ***"
			    <<  sscc.size() << std::endl;
		      for (i = sscc.rem().begin(); i != sscc.rem().end(); ++i)
			{
			  numbered_state_heap::state_index_p spi =
			    h->index((*i));
			  assert(spi.first->compare(*i) == 0);
			  assert(*spi.second != -1);
			  *spi.second = -1;
268

269
			  if (is_livelock_accepting_sscc)
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
270
			    {
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
			      // if it is an accepting sscc add the state to
			      // G (=the livelock-accepting states set)
			      trace << "*** sscc.size() > 1: states: ***"
				    << testing_automata->format_state(*i)
				    << std::endl;
			      state_ta_explicit * livelock_accepting_state =
				down_cast<state_ta_explicit*> (*i);

			      livelock_accepting_state->
				set_livelock_accepting_state(true);

			      if (single_pass_emptiness_check)
				{
				  livelock_accepting_state
				    ->set_accepting_state(true);
				  livelock_accepting_state
				    ->stuttering_reachable_livelock
				    = livelock_accepting_state;
				}
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
290
			    }
291
			}
292

293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
		      assert(!arc.empty());
		      sscc.pop();
		      arc.pop();

		    }

		  // automata reduction
		  testing_automata->delete_stuttering_and_hole_successors(curr);

		  delete succ;
		  // Do not delete CURR: it is a key in H.
		  continue;
		}

	      // Fetch the values destination state we are interested in...
	      state* dest = succ->current_state();

	      bdd acc_cond = succ->current_acceptance_conditions();
	      // ... and point the iterator to the next successor, for
	      // the next iteration.
	      succ->next();
	      // We do not need SUCC from now on.

	      // Are we going to a new state through a stuttering transition?
	      bool is_stuttering_transition =
		testing_automata->get_state_condition(curr)
		== testing_automata->get_state_condition(dest);
	      state* dest_clone = dest;
	      spi = h->find(dest_clone);

	      // Is this a new state?
	      if (!spi.first)
		{
		  if (!is_stuttering_transition)
		    {
		      init_set.push(dest);
		      dest_clone->destroy();
		      continue;
		    }

		  // Number it, stack it, and register its successors
		  // for later processing.
		  h->insert(dest_clone, ++num);
		  sscc.push(num);
		  arc.push(acc_cond);
		  sscc.top().is_accepting =
		    testing_automata->is_accepting_state(dest);

		  tgba_succ_iterator* iter = testing_automata->succ_iter(dest);
		  iter->first();
		  todo.push(pair_state_iter(dest, iter));
		  continue;
		}

	      // If we have reached a dead component, ignore it.
	      if (*spi.second == -1)
		continue;

	      trace << "***compute_livelock_acceptance_states: CYCLE***\n";

	      if (!curr->compare(dest))
		{
		  state_ta_explicit * self_loop_state =
		    down_cast<state_ta_explicit*> (curr);
		  assert(self_loop_state);

		  if (testing_automata->is_accepting_state(self_loop_state)
		      || (acc_cond
			  == testing_automata->all_acceptance_conditions()))
		    {
		      self_loop_state->set_livelock_accepting_state(true);
		      if (single_pass_emptiness_check)
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
365
			{
366
367
368
			  self_loop_state->set_accepting_state(true);
			  self_loop_state->stuttering_reachable_livelock
			    = self_loop_state;
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
369
			}
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
		    }

		  trace
		    << "***compute_livelock_acceptance_states: CYCLE: "
		    << "self_loop_state***\n";
		}

	      // Now this is the most interesting case.  We have reached a
	      // state S1 which is already part of a non-dead SSCC.  Any such
	      // non-dead SSCC has necessarily been crossed by our path to
	      // this state: there is a state S2 in our path which belongs
	      // to this SSCC too.  We are going to merge all states between
	      // this S1 and S2 into this SSCC.
	      //
	      // This merge is easy to do because the order of the SSCC in
	      // ROOT is ascending: we just have to merge all SSCCs from the
	      // top of ROOT that have an index greater to the one of
	      // the SSCC of S2 (called the "threshold").
	      int threshold = *spi.second;
	      std::list<state*> rem;
	      bool acc = false;

	      while (threshold < sscc.top().index)
		{
		  assert(!sscc.empty());
		  assert(!arc.empty());
		  acc |= sscc.top().is_accepting;
		  acc_cond |= sscc.top().condition;
		  acc_cond |= arc.top();
		  rem.splice(rem.end(), sscc.rem());
		  sscc.pop();
		  arc.pop();
		}

	      // Note that we do not always have
	      //  threshold == sscc.top().index
	      // after this loop, the SSCC whose index is threshold might have
	      // been merged with a lower SSCC.

	      // Accumulate all acceptance conditions into the merged SSCC.
	      sscc.top().is_accepting |= acc;
	      sscc.top().condition |= acc_cond;

	      sscc.rem().splice(sscc.rem().end(), rem);

	    }

	}
      delete h;

      if ((artificial_livelock_acc_state != 0)
	  || single_pass_emptiness_check)
	transform_to_single_pass_automaton(testing_automata,
					   artificial_livelock_acc_state);
    }
425

426
427
428
429
430
    ta_explicit*
    build_ta(ta_explicit* ta, bdd atomic_propositions_set_, bool degeneralized,
	     bool single_pass_emptiness_check,
	     bool artificial_livelock_state_mode)
    {
431

432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
      std::stack<state_ta_explicit*> todo;
      const tgba* tgba_ = ta->get_tgba();
      const sba* sba_ = down_cast<const sba*>(tgba_);
      assert(!degeneralized || sba_);

      // build Initial states set:
      state* tgba_init_state = tgba_->get_init_state();

      bdd tgba_condition = tgba_->support_conditions(tgba_init_state);

      bdd satone_tgba_condition;
      while ((satone_tgba_condition = bdd_satoneset(tgba_condition,
						    atomic_propositions_set_,
						    bddtrue)) != bddfalse)
	{
	  tgba_condition -= satone_tgba_condition;
	  state_ta_explicit* init_state;
	  if (degeneralized)
	    {
	      init_state = new
		state_ta_explicit(tgba_init_state->clone(),
				  satone_tgba_condition, true,
				  sba_->state_is_accepting(tgba_init_state));
	    }
	  else
	    {
	      init_state = new
		state_ta_explicit(tgba_init_state->clone(),
				  satone_tgba_condition, true, false);
	    }

	  state_ta_explicit* s = ta->add_state(init_state);
	  assert(s == init_state);
	  ta->add_to_initial_states_set(s);

	  todo.push(init_state);
	}
      tgba_init_state->destroy();
470

471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
      while (!todo.empty())
	{
	  state_ta_explicit* source = todo.top();
	  todo.pop();

	  tgba_succ_iterator* tgba_succ_it =
	    tgba_->succ_iter(source->get_tgba_state());
	  for (tgba_succ_it->first(); !tgba_succ_it->done();
	       tgba_succ_it->next())
	    {
	      const state* tgba_state = tgba_succ_it->current_state();
	      bdd tgba_condition = tgba_succ_it->current_condition();
	      bdd tgba_acceptance_conditions =
                tgba_succ_it->current_acceptance_conditions();
	      bdd satone_tgba_condition;
	      while ((satone_tgba_condition =
		      bdd_satoneset(tgba_condition,
				    atomic_propositions_set_, bddtrue))
		     != bddfalse)
		{
		  tgba_condition -= satone_tgba_condition;

		  bdd all_props = bddtrue;
		  bdd dest_condition;
		  if (satone_tgba_condition == source->get_tgba_condition())
		    while ((dest_condition =
			    bdd_satoneset(all_props,
					  atomic_propositions_set_, bddtrue))
			   != bddfalse)
		      {
			all_props -= dest_condition;
			state_ta_explicit* new_dest;
			if (degeneralized)
			  {
			    new_dest = new state_ta_explicit
			      (tgba_state->clone(),
			       dest_condition,
			       false,
			       sba_->state_is_accepting(tgba_state));
			  }
			else
			  {
			    new_dest = new state_ta_explicit
			      (tgba_state->clone(),
			       dest_condition, false, false);
			  }
			state_ta_explicit* dest = ta->add_state(new_dest);

			if (dest != new_dest)
			  {
			    // the state dest already exists in the automaton
			    new_dest->get_tgba_state()->destroy();
			    delete new_dest;
			  }
			else
			  {
			    todo.push(dest);
			  }

			bdd cs = bdd_setxor(source->get_tgba_condition(),
					    dest->get_tgba_condition());
			ta->create_transition(source, cs,
					      tgba_acceptance_conditions, dest);
		      }
		}
	      tgba_state->destroy();
	    }
	  delete tgba_succ_it;
	}

      state_ta_explicit* artificial_livelock_acc_state = 0;

      trace << "*** build_ta: artificial_livelock_acc_state_mode = ***"
	    << artificial_livelock_state_mode << std::endl;

      if (artificial_livelock_state_mode)
	{
	  single_pass_emptiness_check = true;
	  artificial_livelock_acc_state =
	    new state_ta_explicit(ta->get_tgba()->get_init_state(), bddtrue,
				  false, false, true, 0);
	  trace
	    << "*** build_ta: artificial_livelock_acc_state = ***"
	    << artificial_livelock_acc_state << std::endl;
	}

      compute_livelock_acceptance_states(ta, single_pass_emptiness_check,
					 artificial_livelock_acc_state);
      return ta;
    }
561
562
  }

563
564
  ta_explicit*
  tgba_to_ta(const tgba* tgba_, bdd atomic_propositions_set_,
565
566
      bool degeneralized, bool artificial_initial_state_mode,
      bool single_pass_emptiness_check, bool artificial_livelock_state_mode)
567
568
569
570
571
572
  {
    ta_explicit* ta;

    state* tgba_init_state = tgba_->get_init_state();
    if (artificial_initial_state_mode)
      {
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
573
574
        state_ta_explicit* artificial_init_state =
	  new state_ta_explicit(tgba_init_state->clone(), bddfalse, true);
575
576

        ta = new spot::ta_explicit(tgba_, tgba_->all_acceptance_conditions(),
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
577
				   artificial_init_state);
578
579
580
581
582
583
584
585
      }
    else
      {
        ta = new spot::ta_explicit(tgba_, tgba_->all_acceptance_conditions());
      }
    tgba_init_state->destroy();

    // build ta automata:
586
587
    build_ta(ta, atomic_propositions_set_, degeneralized,
        single_pass_emptiness_check, artificial_livelock_state_mode);
588
589
590
591
592
593
594
595
596

    // (degeneralized=true) => TA
    if (degeneralized)
      return ta;

    // (degeneralized=false) => GTA
    // adapt a GTA to remove acceptance conditions from states
    ta::states_set_t states_set = ta->get_states_set();
    ta::states_set_t::iterator it;
597
    for (it = states_set.begin(); it != states_set.end(); ++it)
598
599
600
601
602
603
604
605
      {
        state_ta_explicit* state = static_cast<state_ta_explicit*> (*it);

        if (state->is_accepting_state())
          {
            state_ta_explicit::transitions* trans = state->get_transitions();
            state_ta_explicit::transitions::iterator it_trans;

Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
606
            for (it_trans = trans->begin(); it_trans != trans->end();
607
		 ++it_trans)
608
609
610
611
612
613
614
615
616
              {
                (*it_trans)->acceptance_conditions
                    = ta->all_acceptance_conditions();
              }

            state->set_accepting_state(false);
          }
      }

617
618
619
    return ta;
  }

620
621
  tgta_explicit*
  tgba_to_tgta(const tgba* tgba_, bdd atomic_propositions_set_)
622
623
  {
    state* tgba_init_state = tgba_->get_init_state();
624
    state_ta_explicit* artificial_init_state = new state_ta_explicit(
625
626
627
        tgba_init_state->clone(), bddfalse, true);
    tgba_init_state->destroy();

628
629
    tgta_explicit* tgta = new spot::tgta_explicit(tgba_,
        tgba_->all_acceptance_conditions(), artificial_init_state);
630

631
632
    // build a Generalized TA automaton involving a single_pass_emptiness_check
    // (without an artificial livelock state):
633
634
    ta_explicit* ta = tgta->get_ta();
    build_ta(ta, atomic_propositions_set_, false, true, false);
635

636
    trace << "***tgba_to_tgbta: POST build_ta***" << std::endl;
637

638
    // adapt a ta automata to build tgta automata :
639
    ta::states_set_t states_set = ta->get_states_set();
640
    ta::states_set_t::iterator it;
641
642
    tgba_succ_iterator* initial_states_iter =
      ta->succ_iter(ta->get_artificial_initial_state());
643
644
    initial_states_iter->first();
    if (initial_states_iter->done())
645
646
647
648
649
      {
	delete initial_states_iter;
	return tgta;
      }
    bdd first_state_condition = initial_states_iter->current_condition();
650
651
652
    delete initial_states_iter;

    bdd bdd_stutering_transition = bdd_setxor(first_state_condition,
653
					      first_state_condition);
654

655
    for (it = states_set.begin(); it != states_set.end(); ++it)
656
657
658
659
660
661
662
      {
        state_ta_explicit* state = static_cast<state_ta_explicit*> (*it);

        state_ta_explicit::transitions* trans = state->get_transitions();
        if (state->is_livelock_accepting_state())
          {
            bool trans_empty = (trans == 0 || trans->empty());
663
            if (trans_empty || state->is_accepting_state())
664
              {
665
666
                ta->create_transition(state, bdd_stutering_transition,
                    ta->all_acceptance_conditions(), state);
667
668
669
              }
          }

670
        if (state->compare(ta->get_artificial_initial_state()))
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
671
672
          ta->create_transition(state, bdd_stutering_transition,
				bddfalse, state);
673

674
675
        state->set_livelock_accepting_state(false);
        state->set_accepting_state(false);
676
        trace << "***tgba_to_tgbta: POST create_transition ***" << std::endl;
677
678
      }

679
    return tgta;
680
  }
681
}