ltlcross.cc

// -*- coding: utf-8 -*-
// Copyright (C) 2012, 2013, 2014, 2015 Laboratoire de Recherche et
// Développement de l'Epita (LRDE).
//
// 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
// the Free Software Foundation; either version 3 of the License, or
// (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
// along with this program.  If not, see <http://www.gnu.org/licenses/>.


#include "common_sys.hh"

#include <string>
#include <iostream>
#include <sstream>
#include <fstream>
#include <cstdlib>
#include <cstdio>
#include <argp.h>
#include <unistd.h>
#include "error.h"
#include "argmatch.h"

#include "common_setup.hh"
#include "common_cout.hh"
#include "common_conv.hh"
#include "common_trans.hh"
#include "common_finput.hh"
#include "dstarparse/public.hh"
#include "hoaparse/public.hh"
#include "ltlast/unop.hh"
#include "ltlvisit/tostring.hh"
#include "ltlvisit/apcollect.hh"
#include "ltlvisit/mutation.hh"
#include "ltlvisit/relabel.hh"
#include "ltlvisit/lbt.hh"
#include "tgbaalgos/lbtt.hh"
#include "tgbaalgos/product.hh"
#include "tgbaalgos/gtec/gtec.hh"
#include "tgbaalgos/randomgraph.hh"
#include "tgbaalgos/sccinfo.hh"
#include "tgbaalgos/isweakscc.hh"
#include "tgbaalgos/reducerun.hh"
#include "tgbaalgos/word.hh"
#include "tgbaalgos/dtgbacomp.hh"
#include "misc/formater.hh"
#include "tgbaalgos/stats.hh"
#include "tgbaalgos/isdet.hh"
#include "misc/escape.hh"
#include "misc/hash.hh"
#include "misc/random.hh"
#include "misc/tmpfile.hh"
#include "misc/timer.hh"

const char argp_program_doc[] ="\
Call several LTL/PSL translators and cross-compare their output to detect \
bugs, or to gather statistics.  The list of formulas to use should be \
supplied on standard input, or using the -f or -F options.\v\
Exit status:\n\
  0  everything went fine (timeouts are OK too)\n\
  1  some translator failed to output something we understand, or failed\n\
     sanity checks (statistics were output nonetheless)\n\
  2  ltlcross aborted on error\n\
";


#define OPT_STATES 1
#define OPT_DENSITY 2
#define OPT_JSON 3
#define OPT_CSV 4
#define OPT_DUPS 5
#define OPT_NOCHECKS 6
#define OPT_STOP_ERR 7
#define OPT_SEED 8
#define OPT_PRODUCTS 9
#define OPT_COLOR 10
#define OPT_NOCOMP 11
#define OPT_OMIT 12
#define OPT_BOGUS 13
#define OPT_VERBOSE 14
#define OPT_GRIND 15

static const argp_option options[] =
  {
    /**************************************************/
    { 0, 0, 0, 0, "ltlcross behavior:", 5 },
    { "allow-dups", OPT_DUPS, 0, 0,
      "translate duplicate formulas in input", 0 },
    { "no-checks", OPT_NOCHECKS, 0, 0,
      "do not perform any sanity checks (negated formulas "
      "will not be translated)", 0 },
    { "no-complement", OPT_NOCOMP, 0, 0,
      "do not complement deterministic automata to perform extra checks", 0 },
    { "stop-on-error", OPT_STOP_ERR, 0, 0,
      "stop on first execution error or failure to pass"
      " sanity checks (timeouts are OK)", 0 },
    /**************************************************/
    { 0, 0, 0, 0, "State-space generation:", 6 },
    { "states", OPT_STATES, "INT", 0,
      "number of the states in the state-spaces (200 by default)", 0 },
    { "density", OPT_DENSITY, "FLOAT", 0,
      "probability, between 0.0 and 1.0, to add a transition between "
      "two states (0.1 by default)", 0 },
    { "seed", OPT_SEED, "INT", 0,
      "seed for the random number generator (0 by default)", 0 },
    { "products", OPT_PRODUCTS, "[+]INT", 0,
      "number of products to perform (1 by default), statistics will be "
      "averaged unless the number is prefixed with '+'", 0 },
    /**************************************************/
    { 0, 0, 0, 0, "Statistics output:", 7 },
    { "json", OPT_JSON, "FILENAME", OPTION_ARG_OPTIONAL,
      "output statistics as JSON in FILENAME or on standard output", 0 },
    { "csv", OPT_CSV, "FILENAME", OPTION_ARG_OPTIONAL,
      "output statistics as CSV in FILENAME or on standard output", 0 },
    { "omit-missing", OPT_OMIT, 0, 0,
      "do not output statistics for timeouts or failed translations", 0 },
    /**************************************************/
    { 0, 0, 0, 0, "Miscellaneous options:", -1 },
    { "color", OPT_COLOR, "WHEN", OPTION_ARG_OPTIONAL,
      "colorize output; WHEN can be 'never', 'always' (the default if "
      "--color is used without argument), or "
      "'auto' (the default if --color is not used)", 0 },
    { "grind", OPT_GRIND, "FILENAME", 0,
      "for each formula for which a problem was detected, write a simpler " \
      "formula that fails on the same test in FILENAME", 0 },
    { "save-bogus", OPT_BOGUS, "FILENAME", 0,
      "save formulas for which problems were detected in FILENAME", 0 },
    { "verbose", OPT_VERBOSE, 0, 0,
      "print what is being done, for debugging", 0 },
    { 0, 0, 0, 0, 0, 0 }
  };

const struct argp_child children[] =
  {
    { &finput_argp, 0, 0, 1 },
    { &trans_argp, 0, 0, 0 },
    { &misc_argp, 0, 0, -1 },
    { 0, 0, 0, 0 }
  };

enum color_type { color_never, color_always, color_if_tty };

static char const *const color_args[] =
{
  "always", "yes", "force",
  "never", "no", "none",
  "auto", "tty", "if-tty", 0
};
static color_type const color_types[] =
{
  color_always, color_always, color_always,
  color_never, color_never, color_never,
  color_if_tty, color_if_tty, color_if_tty
};
ARGMATCH_VERIFY(color_args, color_types);

color_type color_opt = color_if_tty;
const char* bright_red = "\033[01;31m";
const char* bright_blue = "\033[01;34m";
const char* bright_yellow = "\033[01;33m";
const char* reset_color = "\033[m";

unsigned states = 200;
float density = 0.1;
const char* json_output = 0;
const char* csv_output = 0;
bool want_stats = false;
bool allow_dups = false;
bool no_checks = false;
bool no_complement = false;
bool stop_on_error = false;
int seed = 0;
unsigned products = 1;
bool products_avg = true;
bool opt_omit = false;
bool has_sr = false; // Has Streett or Rabin automata to process.
const char* bogus_output_filename = 0;
std::ofstream* bogus_output = 0;
std::ofstream* grind_output = 0;
bool verbose = false;


bool global_error_flag = false;

static std::ostream&
global_error()
{
  global_error_flag = true;
  if (color_opt)
    std::cerr << bright_red;
  return std::cerr;
}

static std::ostream&
example()
{
  if (color_opt)
    std::cerr << bright_yellow;
  return std::cerr;
}


static void
end_error()
{
  if (color_opt)
    std::cerr << reset_color;
}


struct statistics
{
  statistics()
    : ok(false),
      has_in(false),
      status_str(0),
      status_code(0),
      time(0),
      in_type(0),
      in_states(0),
      in_edges(0),
      in_transitions(0),
      in_acc(0),
      in_scc(0),
      states(0),
      edges(0),
      transitions(0),
      acc(0),
      scc(0),
      nonacc_scc(0),
      terminal_scc(0),
      weak_scc(0),
      strong_scc(0),
      nondetstates(0),
      nondeterministic(false),
      terminal_aut(false),
      weak_aut(false),
      strong_aut(false)
  {
  }

  // If OK is false, only the status_str, status_code, and time fields
  // should be valid.
  bool ok;
  // has in_* data to display.
  bool has_in;
  const char* status_str;
  int status_code;
  double time;
  const char* in_type;
  unsigned in_states;
  unsigned in_edges;
  unsigned in_transitions;
  unsigned in_acc;
  unsigned in_scc;
  unsigned states;
  unsigned edges;
  unsigned transitions;
  unsigned acc;
  unsigned scc;
  unsigned nonacc_scc;
  unsigned terminal_scc;
  unsigned weak_scc;
  unsigned strong_scc;
  unsigned nondetstates;
  bool nondeterministic;
  bool terminal_aut;
  bool weak_aut;
  bool strong_aut;
  std::vector<double> product_states;
  std::vector<double> product_transitions;
  std::vector<double> product_scc;

  static void
  fields(std::ostream& os, bool show_exit, bool show_sr)
  {
    if (show_exit)
      os << "\"exit_status\",\"exit_code\",";
    os << "\"time\",";
    if (show_sr)
      os << ("\"in_type\",\"in_states\",\"in_edges\",\"in_transitions\","
	     "\"in_acc\",\"in_scc\",");
    os << ("\"states\","
	   "\"edges\","
	   "\"transitions\","
	   "\"acc\","
	   "\"scc\","
	   "\"nonacc_scc\","
	   "\"terminal_scc\","
	   "\"weak_scc\","
	   "\"strong_scc\","
	   "\"nondet_states\","
	   "\"nondet_aut\","
	   "\"terminal_aut\","
	   "\"weak_aut\","
	   "\"strong_aut\"");
    size_t m = products_avg ? 1U : products;
    for (size_t i = 0; i < m; ++i)
      os << ",\"product_states\",\"product_transitions\",\"product_scc\"";
  }

  void
  to_csv(std::ostream& os, bool show_exit, bool show_sr, const char* na = "")
  {
    if (show_exit)
      os << '"' << status_str << "\"," << status_code << ',';
    os << time << ',';
    if (ok)
      {
	if (has_in)
	  os << '"' << in_type << "\","
	     << in_states << ','
	     << in_edges << ','
	     << in_transitions << ','
	     << in_acc << ','
	     << in_scc << ',';
	else if (show_sr)
	  os << na << ',' << na << ',' << na << ','
	     << na << ',' << na << ',' << na << ',';
	os << states << ','
	   << edges << ','
	   << transitions << ','
	   << acc << ','
	   << scc << ','
	   << nonacc_scc << ','
	   << terminal_scc << ','
	   << weak_scc << ','
	   << strong_scc << ','
	   << nondetstates << ','
	   << nondeterministic << ','
	   << terminal_aut << ','
	   << weak_aut << ','
	   << strong_aut;
	if (!products_avg)
	  {
	    for (size_t i = 0; i < products; ++i)
	      os << ',' << product_states[i]
		 << ',' << product_transitions[i]
		 << ',' << product_scc[i];
	  }
	else
	  {
	    double st = 0.0;
	    double tr = 0.0;
	    double sc = 0.0;
	    for (size_t i = 0; i < products; ++i)
	      {
		st += product_states[i];
		tr += product_transitions[i];
		sc += product_scc[i];
	      }
	    os << ',' << (st / products)
	       << ',' << (tr / products)
	       << ',' << (sc / products);
	  }
      }
    else
      {
	size_t m = products_avg ? 1U : products;
	m *= 3;
	m += 13 + show_sr * 6;
	os << na;
	for (size_t i = 0; i < m; ++i)
	  os << ',' << na;
      }
  }
};

typedef std::vector<statistics> statistics_formula;
typedef std::vector<statistics_formula> statistics_vector;
statistics_vector vstats;
std::vector<std::string> formulas;

static int
parse_opt(int key, char* arg, struct argp_state*)
{
  // This switch is alphabetically-ordered.
  switch (key)
    {
    case ARGP_KEY_ARG:
      translators.push_back(arg);
      break;
    case OPT_BOGUS:
      {
	bogus_output = new std::ofstream(arg);
	if (!*bogus_output)
	  error(2, errno, "cannot open '%s'", arg);
	bogus_output_filename = arg;
	break;
      }
    case OPT_COLOR:
      {
	if (arg)
	  color_opt = XARGMATCH("--color", arg, color_args, color_types);
	else
	  color_opt = color_always;
	break;
      }
    case OPT_CSV:
      want_stats = true;
      csv_output = arg ? arg : "-";
      break;
    case OPT_DENSITY:
      density = to_probability(arg);
      break;
    case OPT_DUPS:
      allow_dups = true;
      break;
    case OPT_GRIND:
      grind_output = new std::ofstream(arg);
      if (!*grind_output)
	error(2, errno, "cannot open '%s'", arg);
      break;
    case OPT_JSON:
      want_stats = true;
      json_output = arg ? arg : "-";
      break;
    case OPT_PRODUCTS:
      if (*arg == '+')
	{
	  products_avg = false;
	  ++arg;
	}
      products = to_pos_int(arg);
      break;
    case OPT_NOCHECKS:
      no_checks = true;
      no_complement = true;
      break;
    case OPT_NOCOMP:
      no_complement = true;
      break;
    case OPT_OMIT:
      opt_omit = true;
      break;
    case OPT_SEED:
      seed = to_pos_int(arg);
      break;
    case OPT_STATES:
      states = to_pos_int(arg);
      break;
    case OPT_STOP_ERR:
      stop_on_error = true;
      break;
    case OPT_VERBOSE:
      verbose = true;
      break;
    default:
      return ARGP_ERR_UNKNOWN;
    }
  return 0;
}

namespace
{
  class xtranslator_runner: public translator_runner
  {
  public:
    xtranslator_runner(spot::bdd_dict_ptr dict)
      : translator_runner(dict)
    {
      has_sr = has('D');
    }

    spot::const_tgba_digraph_ptr
    translate(unsigned int translator_num, char l, statistics_formula* fstats,
	      bool& problem)
    {
      output.reset(translator_num);

      std::ostringstream command;
      format(command, translators[translator_num].cmd);

      assert(output.format != printable_result_filename::None);

      std::string cmd = command.str();
      std::cerr << "Running [" << l << translator_num << "]: "
		<< cmd << std::endl;
      spot::stopwatch sw;
      sw.start();
      int es = exec_with_timeout(cmd.c_str());
      double duration = sw.stop();

      const char* status_str = 0;

      spot::const_tgba_digraph_ptr res = 0;
      if (timed_out)
	{
	  // This is not considered to be a global error.
	  std::cerr << "warning: timeout during execution of command\n";
	  ++timeout_count;
	  status_str = "timeout";
	  problem = false;	// A timeout is not a sign of a bug
	  es = -1;
	}
      else if (WIFSIGNALED(es))
	{
	  status_str = "signal";
	  problem = true;
	  es = WTERMSIG(es);
	  global_error() << "error: execution terminated by signal "
			 << es << ".\n";
	  end_error();
	}
      else if (WIFEXITED(es) && WEXITSTATUS(es) != 0)
	{
	  es = WEXITSTATUS(es);
	  status_str = "exit code";
	  problem = true;
	  global_error() << "error: execution returned exit code "
			 << es << ".\n";
	  end_error();
	}
      else
	{
	  status_str = "ok";
	  problem = false;
	  es = 0;
	  switch (output.format)
	    {
	    case printable_result_filename::Lbtt:
	      {
		std::string error;
		std::ifstream f(output.val()->name());
		if (!f)
		  {
		    status_str = "no output";
		    problem = true;
		    es = -1;
		    global_error() << "Cannot open " << output.val()
				   << std::endl;
		    end_error();
		  }
		else
		  {
		    res = spot::lbtt_parse(f, error, dict);
		    if (!res)
		      {
			status_str = "parse error";
			problem = true;
			es = -1;
			global_error() << ("error: failed to parse output in "
					   "LBTT format: ")
				       << error << std::endl;
			end_error();
		      }
		  }
		break;
	      }
	    case printable_result_filename::Dstar:
	      {
		spot::dstar_parse_error_list pel;
		std::string filename = output.val()->name();
		auto aut = spot::dstar_parse(filename, pel, dict);
		if (!pel.empty())
		  {
		    status_str = "parse error";
		    problem = true;
		    es = -1;
		    std::ostream& err = global_error();
		    err << "error: failed to parse the produced DSTAR"
		      " output.\n";
		    spot::format_dstar_parse_errors(err, filename, pel);
		    end_error();
		    res = nullptr;
		  }
		else
		  {
		    const char* type = 0;
		    switch (aut->type)
		      {
		      case spot::Rabin:
			type = "DRA";
			break;
		      case spot::Streett:
			type = "DSA";
			break;
		      }
		    assert(type);

		    // Gather statistics about the input automaton
		    if (want_stats)
		      {
			statistics* st = &(*fstats)[translator_num];
			st->has_in = true;
			st->in_type = type;
			spot::tgba_sub_statistics s =
			  sub_stats_reachable(aut->aut);
			st->in_states= s.states;
			st->in_edges = s.transitions;
			st->in_transitions = s.sub_transitions;
			st->in_acc = aut->accpair_count;

			st->in_scc = spot::scc_info(aut->aut).scc_count();
		      }
		    // convert it into TGBA for further processing
		    if (verbose)
		      std::cerr << "info: converting " << type << " to TGBA\n";
		    res = dstar_to_tgba(aut);
		  }
		break;
	      }
	    case printable_result_filename::Hoa: // Will also read neverclaims
	      {
		spot::hoa_parse_error_list pel;
		std::string filename = output.val()->name();
		auto aut = spot::hoa_parse(filename, pel, dict);
		if (!pel.empty())
		  {
		    status_str = "parse error";
		    problem = true;
		    es = -1;
		    std::ostream& err = global_error();
		    err << "error: failed to parse the produced automaton.\n";
		    spot::format_hoa_parse_errors(err, filename, pel);
		    end_error();
		    res = nullptr;
		  }
		else if (aut->aborted)
		  {
		    status_str = "aborted";
		    problem = true;
		    es = -1;
		    std::ostream& err = global_error();
		    err << "error: aborted HOA file.\n";
		    end_error();
		    res = nullptr;
		  }
		else
		  {
		    res = aut->aut;
		  }
		break;
	      }
	    case printable_result_filename::None:
	      SPOT_UNREACHABLE();
	    }
	}

      if (want_stats)
	{
	  statistics* st = &(*fstats)[translator_num];
	  st->status_str = status_str;
	  st->status_code = es;
	  st->time = duration;

	  // Compute statistics.
	  if (res)
	    {
	      if (verbose)
		std::cerr << "info: getting statistics\n";
	      st->ok = true;
	      spot::tgba_sub_statistics s = sub_stats_reachable(res);
	      st->states = s.states;
	      st->edges = s.transitions;
	      st->transitions = s.sub_transitions;
	      st->acc = res->acc().num_sets();
	      spot::scc_info m(res);
	      unsigned c = m.scc_count();
	      st->scc = c;
	      st->nondetstates = spot::count_nondet_states(res);
	      st->nondeterministic = st->nondetstates != 0;
	      for (unsigned n = 0; n < c; ++n)
		{
		  if (!m.is_accepting_scc(n))
		    ++st->nonacc_scc;
		  else if (is_terminal_scc(m, n))
		    ++st->terminal_scc;
		  else if (is_weak_scc(m, n))
		    ++st->weak_scc;
		  else
		    ++st->strong_scc;
		}
	      if (st->strong_scc)
		st->strong_aut = true;
	      else if (st->weak_scc)
		st->weak_aut = true;
	      else
		st->terminal_aut = true;
	    }
	}
      output.cleanup();
      return res;
    }
  };

  static bool
  check_empty_prod(const spot::const_tgba_digraph_ptr& aut_i,
		   const spot::const_tgba_digraph_ptr& aut_j,
		   size_t i, size_t j, bool icomp, bool jcomp)
  {
    auto prod = spot::product(aut_i, aut_j);
    auto res = spot::couvreur99(prod)->check();

    if (verbose)
      {
	std::cerr << "info: check_empty ";
	if (icomp)
	  std::cerr << "Comp(N" << i << ')';
	else
	  std::cerr << 'P' << i;
	if (jcomp)
	  std::cerr << "*Comp(P" << j << ')';
	else
	  std::cerr << "*N" << j;
	std::cerr << '\n';
      }

    if (res)
      {
	std::ostream& err = global_error();
	err << "error: ";
	if (icomp)
	  err << "Comp(N" << i << ')';
	else
	  err << 'P' << i;
	if (jcomp)
	  err << "*Comp(P" << j << ')';
	else
	  err << "*N" << j;
	err << " is nonempty";

	auto run = res->accepting_run();
	if (run)
	  {
	    run = reduce_run(prod, run);
	    std::cerr << "; both automata accept the infinite word\n"
		      << "       ";
	    spot::tgba_word w(run);
	    w.simplify();
	    w.print(example(), prod->get_dict()) << '\n';
	  }
	else
	  {
	    std::cerr << '\n';
	  }
	end_error();
      }
    return !!res;
  }

  static bool
  cross_check(const std::vector<spot::scc_info*>& maps, char l, unsigned p)
  {
    size_t m = maps.size();
    if (verbose)
      {
	std::cerr << "info: cross_check {";
	bool first = true;
	for (size_t i = 0; i < m; ++i)
	  {
	    if (first)
	      first = false;
	    else
	      std::cerr << ',';
	    std::cerr << l << i;
	  }
	std::cerr << "}, state-space #" << p << '/' << products << '\n';
      }

    std::vector<bool> res(m);
    unsigned verified = 0;
    unsigned violated = 0;
    for (size_t i = 0; i < m; ++i)
      if (spot::scc_info* m = maps[i])
	{
	  // r == true iff the automaton i is accepting.
	  bool r = false;
	  for (auto& scc: *m)
	    if (scc.is_accepting())
	      {
		r = true;
		break;
	      }
	  res[i] = r;
	  if (r)
	    ++verified;
	  else
	    ++violated;
	}
    if (verified != 0 && violated != 0)
      {
	std::ostream& err = global_error();
	err << "error: {";
	bool first = true;
	for (size_t i = 0; i < m; ++i)
	  if (maps[i] && res[i])
	    {
	      if (first)
		first = false;
	      else
		err << ',';
	      err << l << i;
	    }
	err << "} disagree with {";
	first = true;
	for (size_t i = 0; i < m; ++i)
	  if (maps[i] && !res[i])
	    {
	      if (first)
		first = false;
	      else
		err << ',';
	      err << l << i;
	    }
	err << "} when evaluating ";
	if (products > 1)
	  err << "state-space #" << p << '/' << products << '\n';
	else
	  err << "the state-space\n";
	end_error();
	return true;
      }
    return false;
  }

  typedef std::set<unsigned> state_set;

  // Collect all the states of SSPACE that appear in the accepting SCCs
  // of PROD.  (Trivial SCCs are considered accepting.)
  static void
  states_in_acc(const spot::scc_info* m, state_set& s)
  {
    auto aut = m->get_aut();
    auto ps = aut->get_named_prop<const spot::product_states>("product-states");
    for (auto& scc: *m)
      if (scc.is_accepting() || scc.is_trivial())
	for (auto i: scc.states())
	  // Get the projection on sspace.
	  s.insert((*ps)[i].second);
  }

  static bool
  consistency_check(const spot::scc_info* pos, const spot::scc_info* neg)
  {
    // the states of SSPACE should appear in the accepting SCC of at
    // least one of POS or NEG.  Maybe both.
    state_set s;
    states_in_acc(pos, s);
    states_in_acc(neg, s);
    return s.size() == states;
  }

  typedef
  std::unordered_set<const spot::ltl::formula*,
		     const spot::ptr_hash<const spot::ltl::formula> > fset_t;


  class processor: public job_processor
  {
    spot::bdd_dict_ptr dict = spot::make_bdd_dict();
    xtranslator_runner runner;
    fset_t unique_set;
  public:
    processor():
      runner(dict)
    {
    }

    ~processor()
    {
      fset_t::iterator i = unique_set.begin();
      while (i != unique_set.end())
	(*i++)->destroy();
    }

    int
    process_string(const std::string& input,
		   const char* filename,
		   int linenum)
    {
      spot::ltl::parse_error_list pel;
      const spot::ltl::formula* f = parse_formula(input, pel);

      if (!f || !pel.empty())
	{
	  if (filename)
	    error_at_line(0, 0, filename, linenum, "parse error:");
	  spot::ltl::format_parse_errors(std::cerr, input, pel);
	  if (f)
	    f->destroy();
	  return 1;
	}

      f->clone();
      int res = process_formula(f, filename, linenum);

      if (res && bogus_output)
	*bogus_output << input << std::endl;
      if (res && grind_output)
	{
	  std::string bogus = input;
	  std::vector<const spot::ltl::formula*> mutations;
	  unsigned mutation_count;
	  unsigned mutation_max;
	  while	(res)
	    {
	      std::cerr << "Trying to find a bogus mutation of ";
	      if (color_opt)
		std::cerr << bright_blue;
	      std::cerr << bogus;
	      if (color_opt)
		std::cerr << reset_color;
	      std::cerr << "...\n";

	      mutations = mutate(f);
	      mutation_count = 1;
	      mutation_max = mutations.size();
	      res = 0;
	      for (auto g: mutations)
		{
		  std::cerr << "Mutation " << mutation_count << '/'
			    << mutation_max << ": ";
		  f->destroy();
		  f = g->clone();
		  res = process_formula(g->clone());
		  if (res)
		    break;
		  ++mutation_count;
		}
	      for (auto g: mutations)
		g->destroy();
	      if (res)
		{
		  if (lbt_input)
		    bogus = spot::ltl::to_lbt_string(f);
		  else
		    bogus = spot::ltl::to_string(f);
		  if (bogus_output)
		    *bogus_output << bogus << std::endl;
		}
	    }
	  std::cerr << "Smallest bogus mutation found for ";
	  if (color_opt)
	    std::cerr << bright_blue;
	  std::cerr << input;
	  if (color_opt)
	    std::cerr << reset_color;
	  std::cerr << " is ";
	  if (color_opt)
	    std::cerr << bright_blue;
	  std::cerr << bogus;
	  if (color_opt)
	    std::cerr << reset_color;
	  std::cerr << ".\n\n";
	  *grind_output << bogus << std::endl;
	}
      f->destroy();

      return 0;
    }


    int
    process_formula(const spot::ltl::formula* f,
		    const char* filename = 0, int linenum = 0)
    {
      static unsigned round = 0;

      // If we need LBT atomic proposition in any of the input or
      // output, relabel the formula.
      if (!f->has_lbt_atomic_props() &&
	  (runner.has('l') || runner.has('L') || runner.has('T')))
	{
	  const spot::ltl::formula* g = spot::ltl::relabel(f, spot::ltl::Pnn);
	  f->destroy();
	  f = g;
	}

      // ---------- Positive Formula ----------

      runner.round_formula(f, round);

      // Call formula() before printing anything else, in case it
      // complains.
      std::string fstr = runner.formula();
      if (filename)
	std::cerr << filename << ':';
      if (linenum)
	std::cerr << linenum << ':';
      if (filename || linenum)
	std::cerr << ' ';
      if (color_opt)
	std::cerr << bright_blue;
      std::cerr << fstr << '\n';
      if (color_opt)
	std::cerr << reset_color;

      // Make sure we do not translate the same formula twice.
      if (!allow_dups)
	{
	  if (unique_set.insert(f).second)
	    {
	      f->clone();
	    }
	  else
	    {
	      std::cerr
		<< ("warning: This formula or its negation has already"
		    " been checked.\n         Use --allow-dups if it "
		    "should not be ignored.\n")
		<< std::endl;
	      f->destroy();
	      return 0;
	    }
	}


      int problems = 0;

      // These store the result of the translation of the positive and
      // negative formulas.
      size_t m = translators.size();
      std::vector<spot::const_tgba_digraph_ptr> pos(m);
      std::vector<spot::const_tgba_digraph_ptr> neg(m);
      // These store the complement of the above results, when we can
      // compute it easily.
      std::vector<spot::const_tgba_digraph_ptr> comp_pos(m);
      std::vector<spot::const_tgba_digraph_ptr> comp_neg(m);


      unsigned n = vstats.size();
      vstats.resize(n + (no_checks ? 1 : 2));
      statistics_formula* pstats = &vstats[n];
      statistics_formula* nstats = 0;
      pstats->resize(m);
      formulas.push_back(fstr);

      for (size_t n = 0; n < m; ++n)
	{
	  bool prob;
	  pos[n] = runner.translate(n, 'P', pstats, prob);
	  problems += prob;

	  // If the automaton is deterministic, compute its complement
	  // as well.  Note that if we have computed statistics
	  // already, there is no need to call is_deterministic()
	  // again.
	  if (!no_complement && pos[n]
	      && ((want_stats && !(*pstats)[n].nondeterministic)
		  || (!want_stats && is_deterministic(pos[n]))))