postproc.cc 16.3 KB
Newer Older
1
// -*- coding: utf-8 -*-
2 3
// Copyright (C) 2012-2017 Laboratoire de Recherche et 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 21 22 23 24 25
#include <spot/twaalgos/postproc.hh>
#include <spot/twaalgos/minimize.hh>
#include <spot/twaalgos/simulation.hh>
#include <spot/twaalgos/sccfilter.hh>
#include <spot/twaalgos/degen.hh>
#include <spot/twaalgos/stripacc.hh>
26
#include <cstdlib>
27 28 29 30 31 32 33 34 35
#include <spot/misc/optionmap.hh>
#include <spot/twaalgos/powerset.hh>
#include <spot/twaalgos/isdet.hh>
#include <spot/twaalgos/dtbasat.hh>
#include <spot/twaalgos/dtwasat.hh>
#include <spot/twaalgos/complete.hh>
#include <spot/twaalgos/totgba.hh>
#include <spot/twaalgos/sbacc.hh>
#include <spot/twaalgos/sepsets.hh>
36
#include <spot/twaalgos/determinize.hh>
37
#include <spot/twaalgos/alternation.hh>
38 39 40

namespace spot
{
41 42
  namespace
  {
43 44
    static twa_graph_ptr
    ensure_ba(twa_graph_ptr& a)
45
    {
46
      if (a->num_sets() == 0)
47 48 49 50 51
        {
          auto m = a->set_buchi();
          for (auto& t: a->edges())
            t.acc = m;
        }
52 53 54
      return a;
    }
  }
55

56 57 58 59
  postprocessor::postprocessor(const option_map* opt)
  {
    if (opt)
      {
60 61 62 63 64 65 66 67 68 69 70 71 72
        degen_order_ = opt->get("degen-order", 0);
        degen_reset_ = opt->get("degen-reset", 1);
        degen_cache_ = opt->get("degen-lcache", 1);
        degen_lskip_ = opt->get("degen-lskip", 1);
        degen_lowinit_ = opt->get("degen-lowinit", 0);
        det_scc_ = opt->get("det-scc", 1);
        det_simul_ = opt->get("det-simul", 1);
        det_stutter_ = opt->get("det-stutter", 1);
        simul_ = opt->get("simul", -1);
        scc_filter_ = opt->get("scc-filter", -1);
        ba_simul_ = opt->get("ba-simul", -1);
        tba_determinisation_ = opt->get("tba-det", 0);
        sat_minimize_ = opt->get("sat-minimize", 0);
73 74
        sat_incr_steps_ = opt->get("sat-incr-steps", -2); // -2 or any num < -1
        sat_langmap_ = opt->get("sat-langmap", 0);
75 76 77 78 79 80
        sat_acc_ = opt->get("sat-acc", 0);
        sat_states_ = opt->get("sat-states", 0);
        state_based_ = opt->get("state-based", 0);
        wdba_minimize_ = opt->get("wdba-minimize", 1);

        if (sat_acc_ && sat_minimize_ == 0)
81
          sat_minimize_ = 1;        // Dicho.
82 83 84 85 86 87 88 89 90 91
        if (sat_states_ && sat_minimize_ == 0)
          sat_minimize_ = 1;
        if (sat_minimize_)
          {
            tba_determinisation_ = 1;
            if (sat_acc_ <= 0)
              sat_acc_ = -1;
            if (sat_states_ <= 0)
              sat_states_ = -1;
          }
92 93 94 95 96 97

        // Set default param value if not provided and used.
        if (sat_minimize_ == 2 && sat_incr_steps_ < 0) // Assume algorithm.
            sat_incr_steps_ = 6;
        else if (sat_minimize_ == 3 && sat_incr_steps_ < -1) // Incr algorithm.
            sat_incr_steps_ = 2;
98 99 100
      }
  }

101 102
  twa_graph_ptr
  postprocessor::do_simul(const twa_graph_ptr& a, int opt)
103
  {
104 105
    if (!has_separate_sets(a))
      return a;
106
    switch (opt)
107 108
      {
      case 0:
109
        return a;
110
      case 1:
111
        return simulation(a);
112
      case 2:
113
        return cosimulation(a);
114 115
      case 3:
      default:
116
        return iterated_simulations(a);
117 118 119
      }
  }

120
  twa_graph_ptr
121
  postprocessor::do_sba_simul(const twa_graph_ptr& a, int opt)
122
  {
123 124
    if (ba_simul_ <= 0)
      return a;
125 126 127
    switch (opt)
      {
      case 0:
128
        return a;
129
      case 1:
130
        return simulation_sba(a);
131
      case 2:
132
        return cosimulation_sba(a);
133 134
      case 3:
      default:
135
        return iterated_simulations_sba(a);
136 137 138
      }
  }

139 140
  twa_graph_ptr
  postprocessor::do_degen(const twa_graph_ptr& a)
141
  {
142
    auto d = degeneralize(a,
143 144 145
                          degen_reset_, degen_order_,
                          degen_cache_, degen_lskip_,
                          degen_lowinit_);
146
    return do_sba_simul(d, ba_simul_);
147 148
  }

149 150 151 152 153
  twa_graph_ptr
  postprocessor::do_scc_filter(const twa_graph_ptr& a, bool arg)
  {
    if (scc_filter_ == 0)
      return a;
154 155
    // If the automaton is weak, using transition-based acceptance
    // won't help, so let's preserve it.
156
    if ((state_based_ || a->prop_inherently_weak().is_true())
157
        && a->prop_state_acc().is_true())
158
      return scc_filter_states(a, arg);
159 160 161 162 163 164 165 166 167 168
    else
      return scc_filter(a, arg);
  }

  twa_graph_ptr
  postprocessor::do_scc_filter(const twa_graph_ptr& a)
  {
    return do_scc_filter(a, scc_filter_ > 1);
  }

169 170
#define PREF_ (pref_ & (Small | Deterministic))
#define COMP_ (pref_ & Complete)
171
#define SBACC_ (pref_ & SBAcc)
172

173
  twa_graph_ptr
Alexandre Duret-Lutz's avatar
Alexandre Duret-Lutz committed
174
  postprocessor::run(twa_graph_ptr a, formula f)
175
  {
176 177 178 179 180 181 182 183 184
    if (simul_ < 0)
      simul_ = (level_ == Low) ? 1 : 3;
    if (ba_simul_ < 0)
      ba_simul_ = (level_ == High) ? 3 : 0;
    if (scc_filter_ < 0)
      scc_filter_ = 1;
    if (type_ == BA || SBACC_)
      state_based_ = true;

185
    if (!a->is_existential() &&
186 187 188 189 190 191 192
        // We will probably have to revisit this condition later.
        // Currently, the intent is that postprocessor should never
        // return an alternating automaton, unless it is called with
        // its laxest settings.
        !(type_ == Generic && PREF_ == Any && level_ == Low))
      a = remove_alternation(a);

193
    if (type_ != Generic && !a->acc().is_generalized_buchi())
194
      {
195 196 197
        a = to_generalized_buchi(a);
        if (PREF_ == Any && level_ == Low)
          a = do_scc_filter(a, true);
198
      }
199

200
    if (PREF_ == Any && level_ == Low
201 202 203 204
        && (type_ == Generic
            || type_ == TGBA
            || (type_ == BA && a->is_sba())
            || (type_ == Monitor && a->num_sets() == 0)))
205
      {
206 207 208 209 210
        if (COMP_)
          a = complete(a);
        if (SBACC_)
          a = sbacc(a);
        return a;
211
      }
212

213
    int original_acc = a->num_sets();
214

215
    // Remove useless SCCs.
216
    if (type_ == Monitor)
217 218 219
      // Do not bother about acceptance conditions, they will be
      // ignored.
      a = scc_filter_states(a);
220
    else
221
      a = do_scc_filter(a, (PREF_ == Any));
222

223 224
    if (type_ == Monitor)
      {
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242
        if (PREF_ == Deterministic)
          a = minimize_monitor(a);
        else
          strip_acceptance_here(a);

        if (PREF_ == Any)
          return a;

        a = do_simul(a, simul_);

        // For Small,High we return the smallest between the output of
        // the simulation, and that of the deterministic minimization.
        if (PREF_ == Small && level_ == High && simul_)
          {
            auto m = minimize_monitor(a);
            if (m->num_states() < a->num_states())
              a = m;
          }
243
        a->remove_unused_ap();
244 245 246
        if (COMP_)
          a = complete(a);
        return a;
247 248
      }

249
    if (PREF_ == Any)
250
      {
251 252 253 254 255 256 257
        if (type_ == BA)
          a = do_degen(a);
        if (COMP_)
          a = complete(a);
        if (SBACC_)
          a = sbacc(a);
        return a;
258 259
      }

260
    bool dba_is_wdba = false;
261
    bool dba_is_minimal = false;
262 263
    twa_graph_ptr dba = nullptr;
    twa_graph_ptr sim = nullptr;
264 265 266

    // (Small,Low) is the only configuration where we do not run
    // WDBA-minimization.
267
    if ((PREF_ != Small || level_ != Low) && wdba_minimize_)
268
      {
269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285
        bool reject_bigger = (PREF_ == Small) && (level_ == Medium);
        dba = minimize_obligation(a, f, nullptr, reject_bigger);
        if (dba
            && dba->prop_inherently_weak().is_true()
            && dba->prop_deterministic().is_true())
          {
            // The WDBA is a BA, so no degeneralization is required.
            // We just need to add an acceptance set if there is none.
            dba_is_minimal = dba_is_wdba = true;
            if (type_ == BA)
              ensure_ba(dba);
          }
        else
          {
            // Minimization failed.
            dba = nullptr;
          }
286 287 288 289
      }

    // Run a simulation when wdba failed (or was not run), or
    // at hard levels if we want a small output.
290
    if (!dba || (level_ == High && PREF_ == Small))
291
      {
292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307
        if (((SBACC_ && a->prop_state_acc().is_true())
             || (type_ == BA && a->is_sba()))
            && !tba_determinisation_)
          {
            sim = do_sba_simul(a, ba_simul_);
          }
        else
          {
            sim = do_simul(a, simul_);
            // Degeneralize the result of the simulation if needed.
            // No need to do that if tba_determinisation_ will be used.
            if (type_ == BA && !tba_determinisation_)
              sim = do_degen(sim);
            else if (SBACC_ && !tba_determinisation_)
              sim = sbacc(sim);
          }
308 309
      }

310 311 312 313
    // If WDBA failed, but the simulation returned a deterministic
    // automaton, use it as dba.
    assert(dba || sim);
    if (!dba && is_deterministic(sim))
314
      {
315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331
        std::swap(sim, dba);
        // We postponed degeneralization above i case we would need
        // to perform TBA-determinisation, but now it is clear
        // that we won't perform it.  So do degeneralize.
        if (tba_determinisation_)
          {
            if (type_ == BA)
              {
                dba = do_degen(dba);
                assert(is_deterministic(dba));
              }
            else if (SBACC_)
              {
                dba = sbacc(dba);
                assert(is_deterministic(dba));
              }
          }
332
      }
333 334 335

    // If we don't have a DBA, attempt tba-determinization if requested.
    if (tba_determinisation_ && !dba)
336
      {
337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379
        twa_graph_ptr tmpd = nullptr;
        if (PREF_ == Deterministic
            && f
            && f.is_syntactic_recurrence()
            && sim->num_sets() > 1)
          tmpd = degeneralize_tba(sim);

        auto in = tmpd ? tmpd : sim;

        // These thresholds are arbitrary.
        //
        // For producing Small automata, we assume that a
        // deterministic automaton that is twice the size of the
        // original will never get reduced to a smaller one.  We also
        // do not want more than 2^13 cycles in an SCC.
        //
        // For Deterministic automata, we accept automata that
        // are 8 times bigger, with no more that 2^15 cycle per SCC.
        // The cycle threshold is the most important limit here.  You
        // may up it if you want to try producing larger automata.
        auto tmp =
          tba_determinize_check(in,
                                (PREF_ == Small) ? 2 : 8,
                                1 << ((PREF_ == Small) ? 13 : 15),
                                f);
        if (tmp && tmp != in)
          {
            // There is no point in running the reverse simulation on
            // a deterministic automaton, since all prefixes are
            // unique.
            dba = simulation(tmp);
          }
        if (dba && PREF_ == Deterministic)
          {
            // disregard the result of the simulation.
            sim = nullptr;
          }
        else
          {
            // degeneralize sim, because we did not do it earlier
            if (type_ == BA)
              sim = do_degen(sim);
          }
380 381
      }

382 383
    if (PREF_ == Deterministic && type_ == Generic && !dba)
      {
384 385 386 387 388
        dba = tgba_determinize(to_generalized_buchi(sim),
                               false, det_scc_, det_simul_, det_stutter_);
        if (level_ != Low)
          dba = simulation(dba);
        sim = nullptr;
389 390
      }

391 392 393
    // Now dba contains either the result of WDBA-minimization (in
    // that case dba_is_wdba=true), or some deterministic automaton
    // that is either the result of the simulation or of the
394 395 396 397
    // TBA-determinization (dba_is_wdba=false in both cases), or a
    // parity automaton coming from tgba_determinize().  If the dba is
    // a WDBA, we do not have to run SAT-minimization.  A negative
    // value in sat_minimize_ can force its use for debugging.
398
    if (sat_minimize_ && dba && (!dba_is_wdba || sat_minimize_ < 0))
399
      {
400 401
        if (type_ == Generic)
          throw std::runtime_error
402
            ("postproc() not yet updated to mix sat-minimize and Generic");
403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435
        unsigned target_acc;
        if (type_ == BA)
          target_acc = 1;
        else if (sat_acc_ != -1)
          target_acc = sat_acc_;
        else
          // Take the number of acceptance conditions from the input
          // automaton, not from dba, because dba often has been
          // degeneralized by tba_determinize_check().  Make sure it
          // is at least 1.
          target_acc = original_acc > 0 ? original_acc : 1;

        const_twa_graph_ptr in = nullptr;
        if (target_acc == 1)
          {
            // If we are seeking a minimal DBA with unknown number of
            // states, then we should start from the degeneralized,
            // because the input TBA might be smaller.
            if (state_based_)
              in = degeneralize(dba);
            else
              in = degeneralize_tba(dba);
          }
        else
          {
            in = dba;
          }

        twa_graph_ptr res = complete(in);
        if (target_acc == 1)
          {
            if (sat_states_ != -1)
              res = dtba_sat_synthetize(res, sat_states_, state_based_);
436
            else if (sat_minimize_ == 1)
437
              res = dtba_sat_minimize_dichotomy
438 439 440 441
                (res, state_based_, sat_langmap_);
            else if (sat_minimize_ == 2)
              res = dtba_sat_minimize_assume(res, state_based_, -1,
                                             sat_incr_steps_);
442
            else if (sat_minimize_ == 3)
443 444 445 446
              res = dtba_sat_minimize_incr(res, state_based_, -1,
                                           sat_incr_steps_);
            else // if (sat_minimize == 4 || sat_minimize == -1)
              res = dtba_sat_minimize(res, state_based_);
447 448 449 450 451 452 453 454
          }
        else
          {
            if (sat_states_ != -1)
              res = dtwa_sat_synthetize
                (res, target_acc,
                 acc_cond::acc_code::generalized_buchi(target_acc),
                 sat_states_, state_based_);
455 456
            else if (sat_minimize_ == 1)
              res = dtwa_sat_minimize_dichotomy
457 458
                (res, target_acc,
                 acc_cond::acc_code::generalized_buchi(target_acc),
459
                 state_based_, sat_langmap_);
460
            else if (sat_minimize_ == 2)
461
              res = dtwa_sat_minimize_assume
462 463
                (res, target_acc,
                 acc_cond::acc_code::generalized_buchi(target_acc),
464
                 state_based_, -1, false, sat_incr_steps_);
465
            else if (sat_minimize_ == 3)
466 467 468
              res = dtwa_sat_minimize_incr
                (res, target_acc,
                 acc_cond::acc_code::generalized_buchi(target_acc),
469 470 471
                 state_based_, -1, false, sat_incr_steps_);
            else // if (sat_minimize_ == 4 || sat_minimize_ == -1)
              res = dtwa_sat_minimize
472 473
                (res, target_acc,
                 acc_cond::acc_code::generalized_buchi(target_acc),
474
                 state_based_);
475
          }
476 477 478 479 480 481

        if (res)
          {
            dba = do_scc_filter(res, true);
            dba_is_minimal = true;
          }
482 483
      }

484 485 486
    // Degeneralize the dba resulting from tba-determinization or
    // sat-minimization (which is a TBA) if requested and needed.
    if (dba && !dba_is_wdba && type_ == BA
487
        && !(dba_is_minimal && state_based_ && dba->num_sets() == 1))
488
      dba = degeneralize(dba);
489 490 491

    if (dba && sim)
      {
492 493 494 495
        if (dba->num_states() > sim->num_states())
          dba = nullptr;
        else
          sim = nullptr;
496 497
      }

498
    if (level_ == High && scc_filter_ != 0)
499
      {
500 501 502 503 504 505 506 507 508 509 510 511
        if (dba)
          {
            // Do that even for WDBA, to remove marks from transitions
            // leaving trivial SCCs.
            dba = do_scc_filter(dba, true);
            assert(!sim);
          }
        else if (sim)
          {
            sim = do_scc_filter(sim, true);
            assert(!dba);
          }
512
      }
513 514 515

    sim = dba ? dba : sim;

516 517
    sim->remove_unused_ap();

518
    if (COMP_)
519
      sim = complete(sim);
520 521
    if (SBACC_)
      sim = sbacc(sim);
522

523
    return sim;
524 525
  }
}