diff --git a/iface/dve2/dve2check.cc b/iface/dve2/dve2check.cc
index 052771210..821203264 100644
--- a/iface/dve2/dve2check.cc
+++ b/iface/dve2/dve2check.cc
@@ -157,16 +157,16 @@ checked_main(int argc, char **argv)
 
   spot::ltl::atomic_prop_set ap;
   auto dict = spot::make_bdd_dict();
-  spot::const_kripke_ptr model = 0;
-  spot::const_tgba_ptr prop = 0;
-  spot::const_tgba_ptr product = 0;
-  spot::emptiness_check_instantiator* echeck_inst = 0;
+  spot::const_kripke_ptr model = nullptr;
+  spot::const_tgba_ptr prop = nullptr;
+  spot::const_tgba_ptr product = nullptr;
+  spot::emptiness_check_instantiator_ptr echeck_inst = nullptr;
   int exit_code = 0;
   spot::postprocessor post;
-  const spot::ltl::formula* deadf = 0;
-  const spot::ltl::formula* f = 0;
+  const spot::ltl::formula* deadf = nullptr;
+  const spot::ltl::formula* f = nullptr;
 
-  if (dead == 0 || !strcasecmp(dead, "true"))
+  if (!dead || !strcasecmp(dead, "true"))
     {
       deadf = spot::ltl::constant::true_instance();
     }
@@ -182,8 +182,7 @@ checked_main(int argc, char **argv)
   if (output == EmptinessCheck)
     {
       const char* err;
-      echeck_inst =
-	spot::emptiness_check_instantiator::construct(echeck_algo, &err);
+      echeck_inst = spot::make_emptiness_check_instantiator(echeck_algo, &err);
       if (!echeck_inst)
 	{
 	  std::cerr << "Failed to parse argument of -e/-E near `"
@@ -265,14 +264,14 @@ checked_main(int argc, char **argv)
   assert(echeck_inst);
 
   {
-    spot::emptiness_check* ec = echeck_inst->instantiate(product);
+    auto ec = echeck_inst->instantiate(product);
     bool search_many = echeck_inst->options().get("repeated");
     assert(ec);
     do
       {
 	int memused = spot::memusage();
 	tm.start("running emptiness check");
-	spot::emptiness_check_result* res;
+	spot::emptiness_check_result_ptr res;
 	try
 	  {
 	    res = ec->check();
@@ -315,7 +314,7 @@ checked_main(int argc, char **argv)
 	else if (accepting_run)
 	  {
 
-	    spot::tgba_run* run;
+	    spot::tgba_run_ptr run;
 	    tm.start("computing accepting run");
 	    try
 	      {
@@ -337,31 +336,24 @@ checked_main(int argc, char **argv)
 	    else
 	      {
 		tm.start("reducing accepting run");
-		spot::tgba_run* redrun =
-		  spot::reduce_run(res->automaton(), run);
+		run = spot::reduce_run(res->automaton(), run);
 		tm.stop("reducing accepting run");
-		delete run;
-		run = redrun;
 
 		tm.start("printing accepting run");
 		spot::print_tgba_run(std::cout, product, run);
 		tm.stop("printing accepting run");
 	      }
-	    delete run;
 	  }
 	else
 	  {
 	    std::cout << "an accepting run exists "
 		      << "(use -C to print it)" << std::endl;
 	  }
-	delete res;
       }
     while (search_many);
-    delete ec;
   }
 
  safe_exit:
-  delete echeck_inst;
   if (f)
     f->destroy();
 
diff --git a/src/bin/ltlcross.cc b/src/bin/ltlcross.cc
index 383f57e40..695a0e094 100644
--- a/src/bin/ltlcross.cc
+++ b/src/bin/ltlcross.cc
@@ -1071,9 +1071,7 @@ namespace
 		   size_t i, size_t j, bool icomp, bool jcomp)
   {
     auto prod = spot::product(aut_i, aut_j);
-    spot::emptiness_check* ec = spot::couvreur99(prod);
-    spot::emptiness_check_result* res = ec->check();
-
+    auto res = spot::couvreur99(prod)->check();
     if (res)
       {
 	std::ostream& err = global_error();
@@ -1088,17 +1086,15 @@ namespace
 	  err << "*N" << j;
 	err << " is nonempty";
 
-	spot::tgba_run* run = res->accepting_run();
+	auto run = res->accepting_run();
 	if (run)
 	  {
-	    const spot::tgba_run* runmin = reduce_run(prod, run);
-	    delete run;
+	    run = reduce_run(prod, run);
 	    std::cerr << "; both automata accept the infinite word\n"
 		      << "       ";
-	    spot::tgba_word w(runmin);
+	    spot::tgba_word w(run);
 	    w.simplify();
 	    w.print(example(), prod->get_dict()) << '\n';
-	    delete runmin;
 	  }
 	else
 	  {
@@ -1106,9 +1102,7 @@ namespace
 	  }
 	end_error();
       }
-    delete res;
-    delete ec;
-    return res;
+    return !!res;
   }
 
   static bool
diff --git a/src/dstarparse/dra2ba.cc b/src/dstarparse/dra2ba.cc
index 83ba45898..fe41b347f 100644
--- a/src/dstarparse/dra2ba.cc
+++ b/src/dstarparse/dra2ba.cc
@@ -148,18 +148,10 @@ namespace spot
 	  {
 	    state_set keep(sl.begin(), sl.end());
 	    auto masked = build_tgba_mask_keep(dra->aut, keep, sl.front());
-	    emptiness_check* ec = couvreur99(nra_to_nba(dra, masked));
-	    emptiness_check_result* ecr = ec->check();
-	    delete ecr;
-	    delete ec;
-	    if (ecr)
-	      {
-		// This SCC is not DBA-realizable.
-		//std::cerr << "not DBA-realizable\n";
-		return false;
-	      }
+	    if (!nra_to_nba(dra, masked)->is_empty())
+	      // This SCC is not DBA-realizable.
+	      return false;
 	  }
-	  //std::cerr << "non-accepting\n";
 	  for (state_list::const_iterator i = sl.begin();
 	       i != sl.end(); ++i)
 	    nonfinal.push_back(*i);
diff --git a/src/ltlvisit/contain.cc b/src/ltlvisit/contain.cc
index f083f3c3e..bef1848c8 100644
--- a/src/ltlvisit/contain.cc
+++ b/src/ltlvisit/contain.cc
@@ -69,21 +69,10 @@ namespace spot
       if (i != l->incompatible.end())
 	return i->second;
 
-      auto ec = couvreur99(product(l->translation, g->translation));
-      auto ecr = ec->check();
-      if (!ecr)
-	{
-	  l->incompatible[g] = true;
-	  g->incompatible[l] = true;
-	}
-      else
-	{
-	  l->incompatible[g] = false;
-	  g->incompatible[l] = false;
-	  delete ecr;
-	}
-      delete ec;
-      return !ecr;
+      bool res = product(l->translation, g->translation)->is_empty();
+      l->incompatible[g] = res;
+      g->incompatible[l] = res;
+      return res;
     }
 
 
diff --git a/src/tgba/tgba.cc b/src/tgba/tgba.cc
index 6f957edee..89bc1b00e 100644
--- a/src/tgba/tgba.cc
+++ b/src/tgba/tgba.cc
@@ -21,6 +21,7 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "tgba.hh"
+#include "tgbaalgos/gtec/gtec.hh"
 
 namespace spot
 {
@@ -85,4 +86,13 @@ namespace spot
     return num_acc_;
   }
 
+  bool
+  tgba::is_empty() const
+  {
+    // FIXME: This should be improved based on properties of the
+    // automaton.  For instance we do not need couvreur99 is we know
+    // the automaton is weak.
+    return !couvreur99(shared_from_this())->check();
+  }
+
 }
diff --git a/src/tgba/tgba.hh b/src/tgba/tgba.hh
index c292b30d2..532323285 100644
--- a/src/tgba/tgba.hh
+++ b/src/tgba/tgba.hh
@@ -27,7 +27,6 @@
 #include "fwd.hh"
 #include <cassert>
 #include <memory>
-#include <memory>
 #include "misc/casts.hh"
 #include "misc/hash.hh"
 
@@ -465,7 +464,7 @@ namespace spot
   /// we never represent transitions!  Transition informations are
   /// obtained by querying the iterator over the successors of
   /// a state.
-  class SPOT_API tgba
+  class SPOT_API tgba: public std::enable_shared_from_this<tgba>
   {
   protected:
     tgba();
@@ -641,6 +640,8 @@ namespace spot
     /// the other operand.
     virtual bdd neg_acceptance_conditions() const = 0;
 
+    virtual bool is_empty() const;
+
   protected:
     /// Do the actual computation of tgba::support_conditions().
     virtual bdd compute_support_conditions(const state* state) const = 0;
diff --git a/src/tgbaalgos/emptiness.cc b/src/tgbaalgos/emptiness.cc
index 524faccb0..808a7e4da 100644
--- a/src/tgbaalgos/emptiness.cc
+++ b/src/tgbaalgos/emptiness.cc
@@ -77,8 +77,8 @@ namespace spot
 
   std::ostream&
   print_tgba_run(std::ostream& os,
-		 const_tgba_ptr a,
-		 const tgba_run* run)
+		 const const_tgba_ptr& a,
+		 const const_tgba_run_ptr& run)
   {
     bdd_dict_ptr d = a->get_dict();
     os << "Prefix:" << std::endl;
@@ -109,10 +109,10 @@ namespace spot
   // emptiness_check_result
   //////////////////////////////////////////////////////////////////////
 
-  tgba_run*
+  tgba_run_ptr
   emptiness_check_result::accepting_run()
   {
-    return 0;
+    return nullptr;
   }
 
   const unsigned_statistics*
@@ -149,6 +149,12 @@ namespace spot
     return dynamic_cast<const unsigned_statistics*>(this);
   }
 
+  const ec_statistics*
+  emptiness_check::emptiness_check_statistics() const
+  {
+    return dynamic_cast<const ec_statistics*>(this);
+  }
+
   const char*
   emptiness_check::parse_options(char* options)
   {
@@ -180,29 +186,23 @@ namespace spot
 
   namespace
   {
-    emptiness_check*
-    make_couvreur99(const const_tgba_ptr& a, spot::option_map o)
-    {
-      return couvreur99(a, o);
-    }
-
     struct ec_algo
     {
       const char* name;
-      spot::emptiness_check* (*construct)(const const_tgba_ptr&,
-					  spot::option_map);
+      emptiness_check_ptr(*construct)(const const_tgba_ptr&,
+				      spot::option_map);
       unsigned int min_acc;
       unsigned int max_acc;
     };
 
     ec_algo ec_algos[] =
       {
-	{ "Cou99",     make_couvreur99,                     0, -1U },
-	{ "CVWY90",    spot::magic_search,                  0,   1 },
-	{ "GV04",      spot::explicit_gv04_check,           0,   1 },
-	{ "SE05",      spot::se05,                          0,   1 },
-	{ "Tau03",     spot::explicit_tau03_search,         1, -1U },
-	{ "Tau03_opt", spot::explicit_tau03_opt_search,     0, -1U },
+	{ "Cou99",     couvreur99,                    0, -1U },
+	{ "CVWY90",    magic_search,                  0,   1 },
+	{ "GV04",      explicit_gv04_check,           0,   1 },
+	{ "SE05",      se05,                          0,   1 },
+	{ "Tau03",     explicit_tau03_search,         1, -1U },
+	{ "Tau03_opt", explicit_tau03_opt_search,     0, -1U },
       };
   }
 
@@ -224,14 +224,14 @@ namespace spot
     return static_cast<ec_algo*>(info_)->max_acc;
   }
 
-  emptiness_check*
+  emptiness_check_ptr
   emptiness_check_instantiator::instantiate(const const_tgba_ptr& a) const
   {
     return static_cast<ec_algo*>(info_)->construct(a, o_);
   }
 
-  emptiness_check_instantiator*
-  emptiness_check_instantiator::construct(const char* name, const char** err)
+  emptiness_check_instantiator_ptr
+  make_emptiness_check_instantiator(const char* name, const char** err)
   {
     // Skip spaces.
     while (*name && strchr(" \t\n", *name))
@@ -272,17 +272,26 @@ namespace spot
       if (n == info->name)
 	{
 	  *err = 0;
-	  return new emptiness_check_instantiator(o, info);
+
+	  struct emptiness_check_instantiator_aux:
+            public emptiness_check_instantiator
+	  {
+	    emptiness_check_instantiator_aux(option_map o, void* i):
+	      emptiness_check_instantiator(o, i)
+	    {
+	    }
+	  };
+	  return std::make_shared<emptiness_check_instantiator_aux>(o, info);
 	}
     *err = name;
-    return 0;
+    return nullptr;
   }
 
   // tgba_run_to_tgba
   //////////////////////////////////////////////////////////////////////
 
   tgba_digraph_ptr
-  tgba_run_to_tgba(const const_tgba_ptr& a, const tgba_run* run)
+  tgba_run_to_tgba(const const_tgba_ptr& a, const const_tgba_run_ptr& run)
   {
     auto d = a->get_dict();
     auto res = make_tgba_digraph(d);
diff --git a/src/tgbaalgos/emptiness.hh b/src/tgbaalgos/emptiness.hh
index 51e1a3387..d3fab5e3c 100644
--- a/src/tgbaalgos/emptiness.hh
+++ b/src/tgbaalgos/emptiness.hh
@@ -34,6 +34,8 @@
 namespace spot
 {
   struct tgba_run;
+  typedef std::shared_ptr<tgba_run> tgba_run_ptr;
+  typedef std::shared_ptr<const tgba_run> const_tgba_run_ptr;
 
   /// \addtogroup emptiness_check Emptiness-checks
   /// \ingroup tgba_algorithms
@@ -99,7 +101,7 @@ namespace spot
     /// cannot produce a counter example (that does not mean there
     /// is no counter-example; the mere existence of an instance of
     /// this class asserts the existence of a counter-example).
-    virtual tgba_run* accepting_run();
+    virtual tgba_run_ptr accepting_run();
 
     /// The automaton on which an accepting_run() was found.
     const const_tgba_ptr&
@@ -129,8 +131,11 @@ namespace spot
     option_map o_;		///< The options.
   };
 
+  typedef std::shared_ptr<emptiness_check_result> emptiness_check_result_ptr;
+
   /// Common interface to emptiness check algorithms.
-  class SPOT_API emptiness_check
+  class SPOT_API emptiness_check:
+    public std::enable_shared_from_this<emptiness_check>
   {
   public:
     emptiness_check(const const_tgba_ptr& a, option_map o = option_map())
@@ -173,11 +178,14 @@ namespace spot
     /// Some emptiness_check algorithms, especially those using bit state
     /// hashing may return 0 even if the automaton is not empty.
     /// \see safe()
-    virtual emptiness_check_result* check() = 0;
+    virtual emptiness_check_result_ptr check() = 0;
 
     /// Return statistics, if available.
     virtual const unsigned_statistics* statistics() const;
 
+    /// Return emptiness check statistics, if available.
+    virtual const ec_statistics* emptiness_check_statistics() const;
+
     /// Print statistics, if any.
     virtual std::ostream& print_stats(std::ostream& os) const;
 
@@ -189,25 +197,18 @@ namespace spot
     option_map o_;		///< The options
   };
 
+  typedef std::shared_ptr<emptiness_check> emptiness_check_ptr;
+
+  class emptiness_check_instantiator;
+  typedef std::shared_ptr<emptiness_check_instantiator>
+    emptiness_check_instantiator_ptr;
 
   // Dynamically create emptiness checks.  Given their name and options.
   class SPOT_API emptiness_check_instantiator
   {
   public:
-    /// \brief Create an emptiness-check instantiator, given the name
-    /// of an emptiness check.
-    ///
-    /// \a name should have the form \c "name" or \c "name(options)".
-    ///
-    /// On error, the function returns 0.  If the name of the algorithm
-    /// was unknown, \c *err will be set to \c name.  If some fragment of
-    /// the options could not be parsed, \c *err will point to that
-    /// fragment.
-    static emptiness_check_instantiator* construct(const char* name,
-						   const char** err);
-
     /// Actually instantiate the emptiness check, for \a a.
-    emptiness_check* instantiate(const const_tgba_ptr& a) const;
+    emptiness_check_ptr instantiate(const const_tgba_ptr& a) const;
 
     /// Accessor to the options.
     /// @{
@@ -233,15 +234,27 @@ namespace spot
     ///
     /// \return \c -1U if no upper bound exists.
     unsigned int max_acceptance_conditions() const;
-  private:
+  protected:
     emptiness_check_instantiator(option_map o, void* i);
+
     option_map o_;
     void *info_;
   };
-
-
   /// @}
 
+  /// \brief Create an emptiness-check instantiator, given the name
+  /// of an emptiness check.
+  ///
+  /// \a name should have the form \c "name" or \c "name(options)".
+  ///
+  /// On error, the function returns 0.  If the name of the algorithm
+  /// was unknown, \c *err will be set to \c name.  If some fragment of
+  /// the options could not be parsed, \c *err will point to that
+  /// fragment.
+  SPOT_API emptiness_check_instantiator_ptr
+  make_emptiness_check_instantiator(const char* name, const char** err);
+
+
   /// \addtogroup emptiness_check_algorithms Emptiness-check algorithms
   /// \ingroup emptiness_check
 
@@ -287,14 +300,16 @@ namespace spot
   /// actually exists in the automaton (and will also display any
   /// transition annotation).
   SPOT_API std::ostream&
-  print_tgba_run(std::ostream& os, const_tgba_ptr a, const tgba_run* run);
+  print_tgba_run(std::ostream& os,
+		 const const_tgba_ptr& a,
+		 const const_tgba_run_ptr& run);
 
   /// \brief Return an explicit_tgba corresponding to \a run (i.e. comparable
   /// states are merged).
   ///
   /// \pre \a run must correspond to an actual run of the automaton \a a.
   SPOT_API tgba_digraph_ptr
-  tgba_run_to_tgba(const const_tgba_ptr& a, const tgba_run* run);
+  tgba_run_to_tgba(const const_tgba_ptr& a, const const_tgba_run_ptr& run);
 
   /// @}
 
diff --git a/src/tgbaalgos/gtec/ce.cc b/src/tgbaalgos/gtec/ce.cc
index 4c42b236e..59c77c9bf 100644
--- a/src/tgbaalgos/gtec/ce.cc
+++ b/src/tgbaalgos/gtec/ce.cc
@@ -32,7 +32,7 @@ namespace spot
     {
     public:
       shortest_path(const state_set* t,
-		    const couvreur99_check_status* ecs,
+		    const std::shared_ptr<const couvreur99_check_status>& ecs,
 		    couvreur99_check_result* r)
         : bfs_steps(ecs->aut), target(t), ecs(ecs), r(r)
       {
@@ -68,13 +68,14 @@ namespace spot
     private:
       state_set seen;
       const state_set* target;
-      const couvreur99_check_status* ecs;
+      std::shared_ptr<const couvreur99_check_status> ecs;
       couvreur99_check_result* r;
     };
   }
 
   couvreur99_check_result::couvreur99_check_result
-  (const couvreur99_check_status* ecs, option_map o)
+  (const std::shared_ptr<const couvreur99_check_status>& ecs,
+   option_map o)
     : emptiness_check_result(ecs->aut, o), ecs_(ecs)
   {
   }
@@ -90,10 +91,10 @@ namespace spot
     return count;
   }
 
-  tgba_run*
+  tgba_run_ptr
   couvreur99_check_result::accepting_run()
   {
-    run_ = new tgba_run;
+    run_ = std::make_shared<tgba_run>();
 
     assert(!ecs_->root.empty());
 
@@ -212,7 +213,7 @@ namespace spot
 	    return false;
 	  }
 
-	} b(ecs_, this, acc_to_traverse);
+	} b(ecs_.get(), this, acc_to_traverse);
 
 	substart = b.search(substart, run_->cycle);
 	assert(substart);
diff --git a/src/tgbaalgos/gtec/ce.hh b/src/tgbaalgos/gtec/ce.hh
index 9a6c7fce9..4975056e3 100644
--- a/src/tgbaalgos/gtec/ce.hh
+++ b/src/tgbaalgos/gtec/ce.hh
@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2013 Laboratoire de Recherche et Développement de
+// Copyright (C) 2013, 2014 Laboratoire de Recherche et Développement de
 // l'Epita (LRDE).
 // Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -35,10 +35,11 @@ namespace spot
     public acss_statistics
   {
   public:
-    couvreur99_check_result(const couvreur99_check_status* ecs,
+    couvreur99_check_result(const
+			    std::shared_ptr<const couvreur99_check_status>& ecs,
 			    option_map o = option_map());
 
-    virtual tgba_run* accepting_run();
+    virtual tgba_run_ptr accepting_run();
 
     void print_stats(std::ostream& os) const;
 
@@ -50,8 +51,8 @@ namespace spot
     void accepting_cycle();
 
   private:
-    const couvreur99_check_status* ecs_;
-    tgba_run* run_;
+    std::shared_ptr<const couvreur99_check_status> ecs_;
+    tgba_run_ptr run_;
   };
 }
 
diff --git a/src/tgbaalgos/gtec/gtec.cc b/src/tgbaalgos/gtec/gtec.cc
index 3d47ccca4..ab22a6d30 100644
--- a/src/tgbaalgos/gtec/gtec.cc
+++ b/src/tgbaalgos/gtec/gtec.cc
@@ -45,7 +45,7 @@ namespace spot
       removed_components(0)
   {
     poprem_ = o.get("poprem", 1);
-    ecs_ = new couvreur99_check_status(a);
+    ecs_ = std::make_shared<couvreur99_check_status>(a);
     stats["removed components"] =
 	static_cast<spot::unsigned_statistics::unsigned_fun>
 	(&couvreur99_check::get_removed_components);
@@ -56,7 +56,6 @@ namespace spot
 
   couvreur99_check::~couvreur99_check()
   {
-    delete ecs_;
   }
 
   unsigned
@@ -129,7 +128,7 @@ namespace spot
       }
   }
 
-  emptiness_check_result*
+  emptiness_check_result_ptr
   couvreur99_check::check()
   {
     // We use five main data in this algorithm:
@@ -281,15 +280,15 @@ namespace spot
 	    // cycle.
 	    ecs_->cycle_seed = p.first->first;
             set_states(ecs_->states());
-	    return new couvreur99_check_result(ecs_, options());
+	    return std::make_shared<couvreur99_check_result>(ecs_, options());
 	  }
       }
     // This automaton recognizes no word.
     set_states(ecs_->states());
-    return 0;
+    return nullptr;
   }
 
-  const couvreur99_check_status*
+  std::shared_ptr<const couvreur99_check_status>
   couvreur99_check::result() const
   {
     return ecs_;
@@ -383,7 +382,7 @@ namespace spot
       }
   }
 
-  emptiness_check_result*
+  emptiness_check_result_ptr
   couvreur99_check_shy::check()
   {
     // Position in the loop seeking known successors.
@@ -418,7 +417,7 @@ namespace spot
 		// This automaton recognizes no word.
 		set_states(ecs_->states());
 		assert(poprem_ || depth() == 0);
-		return 0;
+		return nullptr;
 	      }
 
 	    pos = todo.back().q.begin();
@@ -554,7 +553,7 @@ namespace spot
 	    // We have found an accepting SCC.  Clean up TODO.
 	    clear_todo();
 	    set_states(ecs_->states());
-	    return new couvreur99_check_result(ecs_, options());
+	    return std::make_shared<couvreur99_check_result>(ecs_, options());
 	  }
 	// Group the pending successors of formed SCC if requested.
 	if (group_)
@@ -592,12 +591,12 @@ namespace spot
       }
   }
 
-  emptiness_check*
+  emptiness_check_ptr
   couvreur99(const const_tgba_ptr& a, option_map o)
   {
     if (o.get("shy"))
-      return new couvreur99_check_shy(a, o);
-    return  new couvreur99_check(a, o);
+      return std::make_shared<couvreur99_check_shy>(a, o);
+    return std::make_shared<couvreur99_check>(a, o);
   }
 
 }
diff --git a/src/tgbaalgos/gtec/gtec.hh b/src/tgbaalgos/gtec/gtec.hh
index 909e1f145..7a42cb2cc 100644
--- a/src/tgbaalgos/gtec/gtec.hh
+++ b/src/tgbaalgos/gtec/gtec.hh
@@ -136,10 +136,10 @@ namespace spot
   /// states that belong to the same SCC will be considered when
   /// choosing a successor.  Otherwise, only the successor of the
   /// topmost state on the DFS stack are considered.
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   couvreur99(const const_tgba_ptr& a, option_map options = option_map());
 
-
+#ifndef SWIG
   /// \brief An implementation of the Couvreur99 emptiness-check algorithm.
   ///
   /// See the documentation for spot::couvreur99.
@@ -150,7 +150,7 @@ namespace spot
     virtual ~couvreur99_check();
 
     /// Check whether the automaton's language is empty.
-    virtual emptiness_check_result* check();
+    virtual emptiness_check_result_ptr check();
 
     virtual std::ostream& print_stats(std::ostream& os) const;
 
@@ -162,10 +162,10 @@ namespace spot
     /// This status should not be deleted, it is a pointer
     /// to a member of this class that will be deleted when
     /// the couvreur99 object is deleted.
-    const couvreur99_check_status* result() const;
+    std::shared_ptr<const couvreur99_check_status> result() const;
 
   protected:
-    couvreur99_check_status* ecs_;
+    std::shared_ptr<couvreur99_check_status> ecs_;
     /// \brief Remove a strongly component from the hash.
     ///
     /// This function remove all accessible state from a given
@@ -191,7 +191,7 @@ namespace spot
     couvreur99_check_shy(const const_tgba_ptr& a, option_map o = option_map());
     virtual ~couvreur99_check_shy();
 
-    virtual emptiness_check_result* check();
+    virtual emptiness_check_result_ptr check();
 
   protected:
     struct successor {
@@ -239,7 +239,7 @@ namespace spot
     // reprocess the successor states of SCC that have been merged.
     bool group2_;
   };
-
+#endif
 
   /// @}
 }
diff --git a/src/tgbaalgos/gv04.cc b/src/tgbaalgos/gv04.cc
index 757d6e013..42a5aa6b3 100644
--- a/src/tgbaalgos/gv04.cc
+++ b/src/tgbaalgos/gv04.cc
@@ -91,7 +91,7 @@ namespace spot
 	  }
       }
 
-      virtual emptiness_check_result*
+      virtual emptiness_check_result_ptr
       check()
       {
 	top = dftop = -1;
@@ -162,7 +162,7 @@ namespace spot
 	    set_states(h.size());
 	  }
 	if (violation)
-	  return new result(*this);
+	  return std::make_shared<result>(*this);
 	return 0;
       }
 
@@ -287,10 +287,10 @@ namespace spot
 	  return s;
 	}
 
-	virtual tgba_run*
+	virtual tgba_run_ptr
 	accepting_run()
 	{
-	  tgba_run* res = new tgba_run;
+	  auto res = std::make_shared<tgba_run>();
 
 	  update_lowlinks();
 #ifdef TRACE
@@ -409,9 +409,9 @@ namespace spot
 
   } // anonymous
 
-  emptiness_check*
+  emptiness_check_ptr
   explicit_gv04_check(const const_tgba_ptr& a, option_map o)
   {
-    return new gv04(a, o);
+    return std::make_shared<gv04>(a, o);
   }
 }
diff --git a/src/tgbaalgos/gv04.hh b/src/tgbaalgos/gv04.hh
index 4325dc889..0b9ce7d66 100644
--- a/src/tgbaalgos/gv04.hh
+++ b/src/tgbaalgos/gv04.hh
@@ -25,11 +25,10 @@
 
 # include "misc/optionmap.hh"
 # include "tgba/fwd.hh"
+# include "emptiness.hh"
 
 namespace spot
 {
-  class emptiness_check;
-
   /// \brief Emptiness check based on Geldenhuys and Valmari's
   /// TACAS'04 paper.
   /// \ingroup emptiness_check_algorithms
@@ -54,7 +53,7 @@ namespace spot
         isbn    = {3-540-21299-X}
       }
       \endverbatim */
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   explicit_gv04_check(const const_tgba_ptr& a, option_map o = option_map());
 }
 
diff --git a/src/tgbaalgos/magic.cc b/src/tgbaalgos/magic.cc
index 613eb52fa..8f7a28349 100644
--- a/src/tgbaalgos/magic.cc
+++ b/src/tgbaalgos/magic.cc
@@ -88,8 +88,10 @@ namespace spot
       /// check() can be called several times (until it returns a null
       /// pointer) to enumerate all the visited accepting paths. The method
       /// visits only a finite set of accepting paths.
-      virtual emptiness_check_result* check()
+      virtual emptiness_check_result_ptr check()
       {
+	auto t = std::static_pointer_cast<magic_search_>
+	  (this->emptiness_check::shared_from_this());
         if (st_red.empty())
           {
             assert(st_blue.empty());
@@ -98,19 +100,19 @@ namespace spot
             h.add_new_state(s0, BLUE);
             push(st_blue, s0, bddfalse, bddfalse);
             if (dfs_blue())
-              return new magic_search_result(*this, options());
+	      return std::make_shared<magic_search_result>(t, options());
           }
         else
           {
             h.pop_notify(st_red.front().s);
             pop(st_red);
             if (!st_red.empty() && dfs_red())
-              return new magic_search_result(*this, options());
+              return std::make_shared<magic_search_result>(t, options());
             else
               if (dfs_blue())
-                return new magic_search_result(*this, options());
+                return std::make_shared<magic_search_result>(t, options());
           }
-        return 0;
+        return nullptr;
       }
 
       virtual std::ostream& print_stats(std::ostream &os) const
@@ -325,25 +327,25 @@ namespace spot
         public acss_statistics
       {
       public:
-        result_from_stack(magic_search_& ms)
-          : emptiness_check_result(ms.automaton()), ms_(ms)
+        result_from_stack(std::shared_ptr<magic_search_> ms)
+          : emptiness_check_result(ms->automaton()), ms_(ms)
         {
         }
 
-        virtual tgba_run* accepting_run()
+        virtual tgba_run_ptr accepting_run()
         {
-          assert(!ms_.st_blue.empty());
-          assert(!ms_.st_red.empty());
+          assert(!ms_->st_blue.empty());
+          assert(!ms_->st_red.empty());
 
-          tgba_run* run = new tgba_run;
+          auto run = std::make_shared<tgba_run>();
 
           typename stack_type::const_reverse_iterator i, j, end;
           tgba_run::steps* l;
 
           l = &run->prefix;
 
-          i = ms_.st_blue.rbegin();
-          end = ms_.st_blue.rend(); --end;
+          i = ms_->st_blue.rbegin();
+          end = ms_->st_blue.rend(); --end;
           j = i; ++j;
           for (; i != end; ++i, ++j)
             {
@@ -353,12 +355,12 @@ namespace spot
 
           l = &run->cycle;
 
-          j = ms_.st_red.rbegin();
+          j = ms_->st_red.rbegin();
           tgba_run::step s = { i->s->clone(), j->label, j->acc };
           l->push_back(s);
 
           i = j; ++j;
-          end = ms_.st_red.rend(); --end;
+          end = ms_->st_red.rend(); --end;
           for (; i != end; ++i, ++j)
             {
               tgba_run::step s = { i->s->clone(), j->label, j->acc };
@@ -373,7 +375,7 @@ namespace spot
           return 0;
         }
       private:
-        magic_search_& ms_;
+        std::shared_ptr<magic_search_> ms_;
       };
 
 #     define FROM_STACK "ar:from_stack"
@@ -381,8 +383,9 @@ namespace spot
       class magic_search_result: public emptiness_check_result
       {
       public:
-        magic_search_result(magic_search_& m, option_map o = option_map())
-          : emptiness_check_result(m.automaton(), o), ms(m)
+        magic_search_result(const std::shared_ptr<magic_search_>& m,
+			    option_map o = option_map())
+          : emptiness_check_result(m->automaton(), o), ms(m)
         {
           if (options()[FROM_STACK])
             computer = new result_from_stack(ms);
@@ -409,7 +412,7 @@ namespace spot
           delete computer;
         }
 
-        virtual tgba_run* accepting_run()
+        virtual tgba_run_ptr accepting_run()
         {
           return computer->accepting_run();
         }
@@ -421,7 +424,7 @@ namespace spot
 
       private:
         emptiness_check_result* computer;
-        magic_search_& ms;
+	std::shared_ptr<magic_search_> ms;
       };
     };
 
@@ -584,18 +587,20 @@ namespace spot
 
   } // anonymous
 
-  emptiness_check* explicit_magic_search(const const_tgba_ptr& a, option_map o)
+  emptiness_check_ptr
+  explicit_magic_search(const const_tgba_ptr& a, option_map o)
   {
-    return new magic_search_<explicit_magic_search_heap>(a, 0, o);
+    return std::make_shared<magic_search_<explicit_magic_search_heap>>(a, 0, o);
   }
 
-  emptiness_check* bit_state_hashing_magic_search(const const_tgba_ptr& a,
-						  size_t size, option_map o)
+  emptiness_check_ptr
+  bit_state_hashing_magic_search(const const_tgba_ptr& a,
+				 size_t size, option_map o)
   {
-    return new magic_search_<bsh_magic_search_heap>(a, size, o);
+    return std::make_shared<magic_search_<bsh_magic_search_heap>>(a, size, o);
   }
 
-  emptiness_check*
+  emptiness_check_ptr
   magic_search(const const_tgba_ptr& a, option_map o)
   {
     size_t size = o.get("bsh");
diff --git a/src/tgbaalgos/magic.hh b/src/tgbaalgos/magic.hh
index be6967b94..de7e84bb7 100644
--- a/src/tgbaalgos/magic.hh
+++ b/src/tgbaalgos/magic.hh
@@ -26,11 +26,10 @@
 #include <cstddef>
 #include "tgba/fwd.hh"
 #include "misc/optionmap.hh"
+#include "emptiness.hh"
 
 namespace spot
 {
-  class emptiness_check;
-
   /// \addtogroup emptiness_check_algorithms
   /// @{
 
@@ -97,7 +96,7 @@ namespace spot
   ///
   /// \bug The name is misleading.  Magic-search is the algorithm
   /// from \c godefroid.93.pstv, not \c courcoubetis.92.fmsd.
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   explicit_magic_search(const const_tgba_ptr& a,
 			option_map o = option_map());
 
@@ -128,7 +127,7 @@ namespace spot
   ///
   /// \sa spot::explicit_magic_search
   ///
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   bit_state_hashing_magic_search(const const_tgba_ptr& a, size_t size,
 				 option_map o = option_map());
 
@@ -138,7 +137,7 @@ namespace spot
   /// bit_state_hashing_magic_search() according to the \c "bsh" option
   /// in the \c option_map.  If \c "bsh" is set and non null, its value
   /// is used as the size of the hash map.
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   magic_search(const const_tgba_ptr& a, option_map o = option_map());
 
   /// @}
diff --git a/src/tgbaalgos/minimize.cc b/src/tgbaalgos/minimize.cc
index 9b6c82c9c..1e4034fd9 100644
--- a/src/tgbaalgos/minimize.cc
+++ b/src/tgbaalgos/minimize.cc
@@ -260,13 +260,7 @@ namespace spot
 	  // Contrustruct a product between
 	  // LOOP_A, and ORIG_A starting in *IT.
 	  // FIXME: This could be sped up a lot!
-	  emptiness_check* ec = couvreur99(product_at(loop_a, orig_a,
-						      loop_a_init, it));
-	  emptiness_check_result* res = ec->check();
-	  delete res;
-	  delete ec;
-
-	  if (res)
+	  if (!product_at(loop_a, orig_a, loop_a_init, it)->is_empty())
 	    {
 	      accepting = true;
 	      break;
@@ -674,25 +668,15 @@ namespace spot
 
     bool ok = false;
 
-    emptiness_check* ec = couvreur99(product(min_aut_f, aut_neg_f));
-    emptiness_check_result* res = ec->check();
-    if (!res)
+    if (product(min_aut_f, aut_neg_f)->is_empty())
       {
-	delete ec;
-
 	// Complement the minimized WDBA.
 	auto neg_min_aut_f = wdba_complement(min_aut_f);
-	ec = couvreur99(product(aut_f, neg_min_aut_f));
-	res = ec->check();
-	if (!res)
-	  {
-	    // Finally, we are now sure that it was safe
-	    // to minimize the automaton.
-	    ok = true;
-	  }
+	if (product(aut_f, neg_min_aut_f)->is_empty())
+	  // Finally, we are now sure that it was safe
+	  // to minimize the automaton.
+	  ok = true;
       }
-    delete res;
-    delete ec;
 
     if (ok)
       return min_aut_f;
diff --git a/src/tgbaalgos/ndfs_result.hxx b/src/tgbaalgos/ndfs_result.hxx
index 90e8d2f7c..70a3a47b7 100644
--- a/src/tgbaalgos/ndfs_result.hxx
+++ b/src/tgbaalgos/ndfs_result.hxx
@@ -95,9 +95,9 @@ namespace spot
     public stats_interface<ndfs_result<ndfs_search, heap>, heap::Has_Size>
   {
   public:
-    ndfs_result(const ndfs_search& ms)
-      : emptiness_check_result(ms.automaton()), ms_(ms),
-        h_(ms_.get_heap())
+    ndfs_result(const std::shared_ptr<ndfs_search>& ms)
+      : emptiness_check_result(ms->automaton()), ms_(ms),
+        h_(ms->get_heap())
     {
     }
 
@@ -105,10 +105,10 @@ namespace spot
     {
     }
 
-    virtual tgba_run* accepting_run()
+    virtual tgba_run_ptr accepting_run()
     {
-      const stack_type& stb = ms_.get_st_blue();
-      const stack_type& str = ms_.get_st_red();
+      const stack_type& stb = ms_->get_st_blue();
+      const stack_type& str = ms_->get_st_red();
 
       assert(!stb.empty());
 
@@ -195,7 +195,7 @@ namespace spot
 
       assert(!acc_trans.empty());
 
-      tgba_run* run = new tgba_run;
+      auto run = std::make_shared<tgba_run>();
       // construct run->cycle from acc_trans.
       construct_cycle(run, acc_trans);
       // construct run->prefix (a minimal path from the initial state to any
@@ -214,7 +214,7 @@ namespace spot
     }
 
   private:
-    const ndfs_search& ms_;
+    std::shared_ptr<ndfs_search> ms_;
     const heap& h_;
     template <typename T, int n>
     friend struct stats_interface;
@@ -529,7 +529,7 @@ namespace spot
       const heap& h;
     };
 
-    void construct_cycle(tgba_run* run,
+    void construct_cycle(tgba_run_ptr run,
 			 const accepting_transitions_list& acc_trans)
     {
       assert(!acc_trans.empty());
@@ -616,7 +616,7 @@ namespace spot
 	}
     }
 
-    void construct_prefix(tgba_run* run)
+    void construct_prefix(tgba_run_ptr run)
     {
       m_source_trans target;
       transition tmp;
diff --git a/src/tgbaalgos/powerset.cc b/src/tgbaalgos/powerset.cc
index f41cf4770..acd92dde4 100644
--- a/src/tgbaalgos/powerset.cc
+++ b/src/tgbaalgos/powerset.cc
@@ -205,11 +205,7 @@ namespace spot
 	  {
 	    // Check the product between LOOP_A, and ORIG_A starting
 	    // in S.
-	    auto ec = couvreur99(product_at(loop_a, ref_, loop_a_init, s));
-	    emptiness_check_result* res = ec->check();
-	    delete res;
-	    delete ec;
-	    if (res)
+	    if (!product_at(loop_a, ref_, loop_a_init, s)->is_empty())
 	      {
 		accepting = true;
 		break;
@@ -326,9 +322,9 @@ namespace spot
     auto det = tba_determinize(aut, threshold_states, threshold_cycles);
 
     if (!det)
-      return 0;
+      return nullptr;
 
-    if (neg_aut == 0)
+    if (neg_aut == nullptr)
       {
 	const ltl::formula* neg_f =
 	  ltl::unop::instance(ltl::unop::Not, f->clone());
@@ -339,30 +335,13 @@ namespace spot
 	neg_aut = scc_filter(neg_aut, true);
       }
 
-    bool ok = false;
+    if (product(det, neg_aut)->is_empty())
+      // Complement the DBA.
+      if (product(aut, dtgba_complement(det))->is_empty())
+	// Finally, we are now sure that it was safe
+	// to determinize the automaton.
+	return det;
 
-    auto ec = couvreur99(product(det, neg_aut));
-    auto res = ec->check();
-    if (!res)
-      {
-	delete ec;
-
-	// Complement the DBA.
-	ec = couvreur99(product(aut, dtgba_complement(det)));
-	res = ec->check();
-
-	if (!res)
-	  {
-	    // Finally, we are now sure that it was safe
-	    // to determinize the automaton.
-	    ok = true;
-	  }
-      }
-    delete res;
-    delete ec;
-
-    if (ok)
-      return det;
     return aut;
   }
 }
diff --git a/src/tgbaalgos/projrun.cc b/src/tgbaalgos/projrun.cc
index fb140be47..278b42b65 100644
--- a/src/tgbaalgos/projrun.cc
+++ b/src/tgbaalgos/projrun.cc
@@ -24,12 +24,12 @@
 namespace spot
 {
 
-  tgba_run*
+  tgba_run_ptr
   project_tgba_run(const const_tgba_ptr& a_run,
 		   const const_tgba_ptr& a_proj,
-		   const tgba_run* run)
+		   const const_tgba_run_ptr& run)
   {
-    tgba_run* res = new tgba_run;
+    auto res = std::make_shared<tgba_run>();
     for (tgba_run::steps::const_iterator i = run->prefix.begin();
 	 i != run->prefix.end(); ++i)
       {
diff --git a/src/tgbaalgos/projrun.hh b/src/tgbaalgos/projrun.hh
index 92b9a9570..a43dcca2e 100644
--- a/src/tgbaalgos/projrun.hh
+++ b/src/tgbaalgos/projrun.hh
@@ -26,6 +26,7 @@
 # include "misc/common.hh"
 # include <iosfwd>
 # include "tgba/fwd.hh"
+# include "tgbaalgos/emptiness.hh"
 
 namespace spot
 {
@@ -41,10 +42,10 @@ namespace spot
   /// \param a_run the automata on which the run was generated
   /// \param a_proj the automata on which to project the run
   /// \return true iff the run could be completed
-  SPOT_API tgba_run*
+  SPOT_API tgba_run_ptr
   project_tgba_run(const const_tgba_ptr& a_run,
 		   const const_tgba_ptr& a_proj,
-		   const tgba_run* run);
+		   const const_tgba_run_ptr& run);
 }
 
 #endif // SPOT_TGBAALGOS_PROJRUN_HH
diff --git a/src/tgbaalgos/reducerun.cc b/src/tgbaalgos/reducerun.cc
index ce4381625..c1f02549a 100644
--- a/src/tgbaalgos/reducerun.cc
+++ b/src/tgbaalgos/reducerun.cc
@@ -1,7 +1,8 @@
-// Copyright (C) 2011, 2013 Laboratoire de Recherche et Développement
-// de l'Epita (LRDE).
+// -*- coding: utf-8 -*-
+// Copyright (C) 2011, 2013, 2014 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
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
 // et Marie Curie.
 //
 // This file is part of Spot, a model checking library.
@@ -86,10 +87,10 @@ namespace spot
     };
   }
 
-  tgba_run*
-  reduce_run(const const_tgba_ptr& a, const tgba_run* org)
+  tgba_run_ptr
+  reduce_run(const const_tgba_ptr& a, const const_tgba_run_ptr& org)
   {
-    tgba_run* res = new tgba_run;
+    auto res = std::make_shared<tgba_run>();
     state_set ss;
     shortest_path shpath(a);
     shpath.set_target(&ss);
diff --git a/src/tgbaalgos/reducerun.hh b/src/tgbaalgos/reducerun.hh
index 9dadcef29..4a251f22c 100644
--- a/src/tgbaalgos/reducerun.hh
+++ b/src/tgbaalgos/reducerun.hh
@@ -25,18 +25,17 @@
 
 # include "misc/common.hh"
 # include "tgba/fwd.hh"
+# include "tgbaalgos/emptiness.hh"
 
 namespace spot
 {
-  struct tgba_run;
-
   /// \ingroup tgba_run
   /// \brief Reduce an accepting run.
   ///
   /// Return a run which is accepting for \a a and that is no longer
   /// than \a org.
-  SPOT_API tgba_run*
-  reduce_run(const const_tgba_ptr& a, const tgba_run* org);
+  SPOT_API tgba_run_ptr
+  reduce_run(const const_tgba_ptr& a, const const_tgba_run_ptr& org);
 }
 
 #endif // SPOT_TGBAALGOS_REDUCERUN_HH
diff --git a/src/tgbaalgos/replayrun.cc b/src/tgbaalgos/replayrun.cc
index b5d9a06b3..52ba65379 100644
--- a/src/tgbaalgos/replayrun.cc
+++ b/src/tgbaalgos/replayrun.cc
@@ -32,7 +32,8 @@ namespace spot
   namespace
   {
     void
-    print_annotation(std::ostream& os, const_tgba_ptr a,
+    print_annotation(std::ostream& os,
+		     const const_tgba_ptr& a,
 		     const tgba_succ_iterator* i)
     {
       std::string s = a->transition_annotation(i);
@@ -44,7 +45,7 @@ namespace spot
 
   bool
   replay_tgba_run(std::ostream& os, const const_tgba_ptr& a,
-		  const tgba_run* run, bool debug)
+		  const const_tgba_run_ptr& run, bool debug)
   {
     const state* s = a->get_init_state();
     int serial = 1;
diff --git a/src/tgbaalgos/replayrun.hh b/src/tgbaalgos/replayrun.hh
index 1f6ad50dc..169685dd7 100644
--- a/src/tgbaalgos/replayrun.hh
+++ b/src/tgbaalgos/replayrun.hh
@@ -26,6 +26,7 @@
 # include "misc/common.hh"
 # include <iosfwd>
 # include "tgba/fwd.hh"
+# include "tgbaalgos/emptiness.hh"
 
 namespace spot
 {
@@ -48,7 +49,8 @@ namespace spot
   /// \return true iff the run could be completed
   SPOT_API bool
   replay_tgba_run(std::ostream& os,
-		  const const_tgba_ptr& a, const tgba_run* run,
+		  const const_tgba_ptr& a,
+		  const const_tgba_run_ptr& run,
 		  bool debug = false);
 }
 
diff --git a/src/tgbaalgos/rundotdec.cc b/src/tgbaalgos/rundotdec.cc
index 826403fe6..17a604887 100644
--- a/src/tgbaalgos/rundotdec.cc
+++ b/src/tgbaalgos/rundotdec.cc
@@ -26,7 +26,8 @@
 namespace spot
 {
 
-  tgba_run_dotty_decorator::tgba_run_dotty_decorator(const tgba_run* run)
+  tgba_run_dotty_decorator::tgba_run_dotty_decorator(const
+						     const_tgba_run_ptr& run)
     : run_(run)
   {
     int n = 1;
diff --git a/src/tgbaalgos/rundotdec.hh b/src/tgbaalgos/rundotdec.hh
index cad77251a..433f30314 100644
--- a/src/tgbaalgos/rundotdec.hh
+++ b/src/tgbaalgos/rundotdec.hh
@@ -38,7 +38,7 @@ namespace spot
   class SPOT_API tgba_run_dotty_decorator: public dotty_decorator
   {
   public:
-    tgba_run_dotty_decorator(const tgba_run* run);
+    tgba_run_dotty_decorator(const const_tgba_run_ptr& run);
     virtual ~tgba_run_dotty_decorator();
 
     virtual std::string state_decl(const const_tgba_ptr& a,
@@ -52,7 +52,7 @@ namespace spot
 				  const tgba_succ_iterator* si,
 				  const std::string& label);
   private:
-    const tgba_run* run_;
+    const_tgba_run_ptr run_;
     typedef std::pair<tgba_run::steps::const_iterator, int> step_num;
     typedef std::list<step_num> step_set;
     typedef std::map<const state*, std::pair<step_set, step_set>,
diff --git a/src/tgbaalgos/se05.cc b/src/tgbaalgos/se05.cc
index 2f2381978..ccc0b71c6 100644
--- a/src/tgbaalgos/se05.cc
+++ b/src/tgbaalgos/se05.cc
@@ -88,8 +88,10 @@ namespace spot
       /// check() can be called several times (until it returns a null
       /// pointer) to enumerate all the visited accepting paths. The method
       /// visits only a finite set of accepting paths.
-      virtual emptiness_check_result* check()
+      virtual emptiness_check_result_ptr check()
       {
+	auto t = std::static_pointer_cast<se05_search>
+	  (this->emptiness_check::shared_from_this());
         if (st_red.empty())
           {
             assert(st_blue.empty());
@@ -98,17 +100,17 @@ namespace spot
             h.add_new_state(s0, CYAN);
             push(st_blue, s0, bddfalse, bddfalse);
             if (dfs_blue())
-              return new se05_result(*this, options());
+              return std::make_shared<se05_result>(t, options());
           }
         else
           {
             h.pop_notify(st_red.front().s);
             pop(st_red);
             if (!st_red.empty() && dfs_red())
-              return new se05_result(*this, options());
+              return std::make_shared<se05_result>(t, options());
             else
               if (dfs_blue())
-                return new se05_result(*this, options());
+                return std::make_shared<se05_result>(t, options());
           }
         return 0;
       }
@@ -330,27 +332,27 @@ namespace spot
         public acss_statistics
       {
       public:
-        result_from_stack(se05_search& ms)
-          : emptiness_check_result(ms.automaton()), ms_(ms)
+        result_from_stack(const std::shared_ptr<se05_search>& ms)
+          : emptiness_check_result(ms->automaton()), ms_(ms)
         {
         }
 
-        virtual tgba_run* accepting_run()
+        virtual tgba_run_ptr accepting_run()
         {
-          assert(!ms_.st_blue.empty());
-          assert(!ms_.st_red.empty());
+          assert(!ms_->st_blue.empty());
+          assert(!ms_->st_red.empty());
 
-          tgba_run* run = new tgba_run;
+          auto run = std::make_shared<tgba_run>();
 
           typename stack_type::const_reverse_iterator i, j, end;
           tgba_run::steps* l;
 
-          const state* target = ms_.st_red.front().s;
+          const state* target = ms_->st_red.front().s;
 
           l = &run->prefix;
 
-          i = ms_.st_blue.rbegin();
-          end = ms_.st_blue.rend(); --end;
+          i = ms_->st_blue.rbegin();
+          end = ms_->st_blue.rend(); --end;
           j = i; ++j;
           for (; i != end; ++i, ++j)
             {
@@ -364,12 +366,12 @@ namespace spot
             l = &run->cycle;
           assert(l == &run->cycle);
 
-          j = ms_.st_red.rbegin();
+          j = ms_->st_red.rbegin();
           tgba_run::step s = { i->s->clone(), j->label, j->acc };
           l->push_back(s);
 
           i = j; ++j;
-          end = ms_.st_red.rend(); --end;
+          end = ms_->st_red.rend(); --end;
           for (; i != end; ++i, ++j)
             {
               tgba_run::step s = { i->s->clone(), j->label, j->acc };
@@ -384,7 +386,7 @@ namespace spot
           return 0;
         }
       private:
-        se05_search& ms_;
+	std::shared_ptr<se05_search> ms_;
       };
 
 #     define FROM_STACK "ar:from_stack"
@@ -392,8 +394,9 @@ namespace spot
       class se05_result: public emptiness_check_result
       {
       public:
-        se05_result(se05_search& m, option_map o = option_map())
-          : emptiness_check_result(m.automaton(), o), ms(m)
+        se05_result(const std::shared_ptr<se05_search>& m,
+		    option_map o = option_map())
+          : emptiness_check_result(m->automaton(), o), ms(m)
         {
           if (options()[FROM_STACK])
             computer = new result_from_stack(ms);
@@ -420,7 +423,7 @@ namespace spot
           delete computer;
         }
 
-        virtual tgba_run* accepting_run()
+        virtual tgba_run_ptr accepting_run()
         {
           return computer->accepting_run();
         }
@@ -432,7 +435,7 @@ namespace spot
 
       private:
         emptiness_check_result* computer;
-        se05_search& ms;
+	std::shared_ptr<se05_search> ms;
       };
     };
 
@@ -675,19 +678,20 @@ namespace spot
 
   } // anonymous
 
-  emptiness_check* explicit_se05_search(const const_tgba_ptr& a, option_map o)
+  emptiness_check_ptr
+  explicit_se05_search(const const_tgba_ptr& a, option_map o)
   {
-    return new se05_search<explicit_se05_search_heap>(a, 0, o);
+    return std::make_shared<se05_search<explicit_se05_search_heap>>(a, 0, o);
   }
 
-  emptiness_check* bit_state_hashing_se05_search(const const_tgba_ptr& a,
-						 size_t size,
-						 option_map o)
+  emptiness_check_ptr
+  bit_state_hashing_se05_search(const const_tgba_ptr& a,
+				size_t size, option_map o)
   {
-    return new se05_search<bsh_se05_search_heap>(a, size, o);
+    return std::make_shared<se05_search<bsh_se05_search_heap>>(a, size, o);
   }
 
-  emptiness_check*
+  emptiness_check_ptr
   se05(const const_tgba_ptr& a, option_map o)
   {
     size_t size = o.get("bsh");
diff --git a/src/tgbaalgos/se05.hh b/src/tgbaalgos/se05.hh
index d50a9d856..a2230aca1 100644
--- a/src/tgbaalgos/se05.hh
+++ b/src/tgbaalgos/se05.hh
@@ -26,11 +26,10 @@
 # include <cstddef>
 # include "misc/optionmap.hh"
 # include "tgba/fwd.hh"
+# include "emptiness.hh"
 
 namespace spot
 {
-  class emptiness_check;
-
   /// \addtogroup emptiness_check_algorithms
   /// @{
 
@@ -102,7 +101,7 @@ namespace spot
   ///
   /// \sa spot::explicit_magic_search
   ///
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   explicit_se05_search(const const_tgba_ptr& a, option_map o = option_map());
 
   /// \brief Returns an emptiness checker on the spot::tgba automaton \a a.
@@ -132,7 +131,7 @@ namespace spot
   ///
   /// \sa spot::explicit_se05_search
   ///
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   bit_state_hashing_se05_search(const const_tgba_ptr& a, size_t size,
 				option_map o = option_map());
 
@@ -143,7 +142,7 @@ namespace spot
   /// bit_state_hashing_se05_search() according to the \c "bsh" option
   /// in the \c option_map.  If \c "bsh" is set and non null, its value
   /// is used as the size of the hash map.
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   se05(const const_tgba_ptr& a, option_map o);
 
   /// @}
diff --git a/src/tgbaalgos/tau03.cc b/src/tgbaalgos/tau03.cc
index e18c5d5c6..7720a6376 100644
--- a/src/tgbaalgos/tau03.cc
+++ b/src/tgbaalgos/tau03.cc
@@ -83,18 +83,20 @@ namespace spot
       ///
       /// \return non null pointer iff the algorithm has found an
       /// accepting path.
-      virtual emptiness_check_result* check()
+      virtual emptiness_check_result_ptr check()
       {
         if (!st_blue.empty())
-            return 0;
+            return nullptr;
         assert(st_red.empty());
         const state* s0 = a_->get_init_state();
         inc_states();
         h.add_new_state(s0, BLUE);
         push(st_blue, s0, bddfalse, bddfalse);
+	auto t = std::static_pointer_cast<tau03_search>
+	  (this->emptiness_check::shared_from_this());
         if (dfs_blue())
-          return new ndfs_result<tau03_search<heap>, heap>(*this);
-        return 0;
+          return std::make_shared<ndfs_result<tau03_search<heap>, heap>>(t);
+        return nullptr;
       }
 
       virtual std::ostream& print_stats(std::ostream &os) const
@@ -374,9 +376,10 @@ namespace spot
 
   } // anonymous
 
-  emptiness_check* explicit_tau03_search(const const_tgba_ptr& a, option_map o)
+  emptiness_check_ptr
+  explicit_tau03_search(const const_tgba_ptr& a, option_map o)
   {
-    return new tau03_search<explicit_tau03_search_heap>(a, 0, o);
+    return std::make_shared<tau03_search<explicit_tau03_search_heap>>(a, 0, o);
   }
 
 }
diff --git a/src/tgbaalgos/tau03.hh b/src/tgbaalgos/tau03.hh
index cf99a6239..ce35f1faf 100644
--- a/src/tgbaalgos/tau03.hh
+++ b/src/tgbaalgos/tau03.hh
@@ -25,11 +25,10 @@
 
 # include "misc/optionmap.hh"
 # include "tgba/fwd.hh"
+# include "emptiness.hh"
 
 namespace spot
 {
-  class emptiness_check;
-
   /// \addtogroup emptiness_check_algorithms
   /// @{
 
@@ -96,7 +95,7 @@ namespace spot
       }
       \endverbatim */
   ///
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   explicit_tau03_search(const const_tgba_ptr& a, option_map o = option_map());
 
   /// @}
diff --git a/src/tgbaalgos/tau03opt.cc b/src/tgbaalgos/tau03opt.cc
index 0b042e1ed..e490ebc44 100644
--- a/src/tgbaalgos/tau03opt.cc
+++ b/src/tgbaalgos/tau03opt.cc
@@ -108,18 +108,20 @@ namespace spot
       ///
       /// \return non null pointer iff the algorithm has found an
       /// accepting path.
-      virtual emptiness_check_result* check()
+      virtual emptiness_check_result_ptr check()
       {
         if (!st_blue.empty())
-            return 0;
+            return nullptr;
         assert(st_red.empty());
         const state* s0 = a_->get_init_state();
         inc_states();
         h.add_new_state(s0, CYAN, current_weight);
         push(st_blue, s0, bddfalse, bddfalse);
+	auto t = std::static_pointer_cast<tau03_opt_search>
+	  (this->emptiness_check::shared_from_this());
         if (dfs_blue())
-          return new ndfs_result<tau03_opt_search<heap>, heap>(*this);
-        return 0;
+          return std::make_shared<ndfs_result<tau03_opt_search<heap>, heap>>(t);
+        return nullptr;
       }
 
       virtual std::ostream& print_stats(std::ostream &os) const
@@ -572,10 +574,12 @@ namespace spot
 
   } // anonymous
 
-  emptiness_check* explicit_tau03_opt_search(const const_tgba_ptr& a,
-					     option_map o)
+  emptiness_check_ptr
+  explicit_tau03_opt_search(const const_tgba_ptr& a, option_map o)
   {
-    return new tau03_opt_search<explicit_tau03_opt_search_heap>(a, 0, o);
+    return
+      std::make_shared<tau03_opt_search<explicit_tau03_opt_search_heap>>(a,
+									 0, o);
   }
 
 }
diff --git a/src/tgbaalgos/tau03opt.hh b/src/tgbaalgos/tau03opt.hh
index f05addaa4..10546a5f8 100644
--- a/src/tgbaalgos/tau03opt.hh
+++ b/src/tgbaalgos/tau03opt.hh
@@ -25,11 +25,10 @@
 
 # include "misc/optionmap.hh"
 # include "tgba/fwd.hh"
+# include "emptiness.hh"
 
 namespace spot
 {
-  class emptiness_check;
-
   /// \addtogroup emptiness_check_algorithms
   /// @{
 
@@ -98,7 +97,7 @@ namespace spot
   /// the path stored in the blue stack. Such a vector is associated to each
   /// state of this stack.
   ///
-  SPOT_API emptiness_check*
+  SPOT_API emptiness_check_ptr
   explicit_tau03_opt_search(const const_tgba_ptr& a,
 			    option_map o = option_map());
 
diff --git a/src/tgbaalgos/word.cc b/src/tgbaalgos/word.cc
index 50445b3a7..525c01d98 100644
--- a/src/tgbaalgos/word.cc
+++ b/src/tgbaalgos/word.cc
@@ -23,7 +23,7 @@
 
 namespace spot
 {
-  tgba_word::tgba_word(const tgba_run* run)
+  tgba_word::tgba_word(const tgba_run_ptr run)
   {
     for (tgba_run::steps::const_iterator i = run->prefix.begin();
 	 i != run->prefix.end(); ++i)
diff --git a/src/tgbaalgos/word.hh b/src/tgbaalgos/word.hh
index c5ab33860..7c9b4f9c6 100644
--- a/src/tgbaalgos/word.hh
+++ b/src/tgbaalgos/word.hh
@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2013 Laboratoire de Recherche et Développement de
+// Copyright (C) 2013, 2014 Laboratoire de Recherche et Développement de
 // l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -29,7 +29,7 @@ namespace spot
   /// \brief An infinite word stored as a lasso.
   struct SPOT_API tgba_word
   {
-    tgba_word(const tgba_run* run);
+    tgba_word(const tgba_run_ptr run);
     void simplify();
     std::ostream& print(std::ostream& os, const bdd_dict_ptr& d) const;
 
diff --git a/src/tgbatest/checkpsl.cc b/src/tgbatest/checkpsl.cc
index 7767ffd14..81a7d4e65 100644
--- a/src/tgbatest/checkpsl.cc
+++ b/src/tgbatest/checkpsl.cc
@@ -29,7 +29,6 @@
 #include "tgbaalgos/ltl2taa.hh"
 #include "tgbaalgos/sccfilter.hh"
 #include "tgba/tgbaproduct.hh"
-#include "tgbaalgos/gtec/gtec.hh"
 #include "tgbaalgos/dotty.hh"
 #include "tgbaalgos/dupexp.hh"
 
@@ -76,14 +75,11 @@ main(int argc, char** argv)
       {
 	auto apos = scc_filter(ltl_to_tgba_fm(fpos, d));
 	auto aneg = scc_filter(ltl_to_tgba_fm(fneg, d));
-	auto ec = spot::couvreur99(spot::product(apos, aneg));
-	auto res = ec->check();
-	if (res)
+	if (!spot::product(apos, aneg)->is_empty())
 	  {
-	  std::cerr << "non-empty intersection between pos and neg (FM)\n";
-	  exit(2);
+	    std::cerr << "non-empty intersection between pos and neg (FM)\n";
+	    exit(2);
 	  }
-	delete ec;
 
 	// Run make_future_conditions_collector, without testing the output.
 	auto fc = spot::make_future_conditions_collector(apos, true);
@@ -93,28 +89,22 @@ main(int argc, char** argv)
       {
 	auto apos = scc_filter(ltl_to_tgba_fm(fpos, d, true));
 	auto aneg = scc_filter(ltl_to_tgba_fm(fneg, d, true));
-	auto ec = spot::couvreur99(spot::product(apos, aneg));
-	auto res = ec->check();
-	if (res)
+	if (!spot::product(apos, aneg)->is_empty())
 	  {
 	    std::cerr << "non-empty intersection between pos and neg (FM -x)\n";
 	    exit(2);
 	  }
-	delete ec;
       }
 
       if (fpos->is_ltl_formula())
 	{
 	  auto apos = scc_filter(spot::tgba_dupexp_dfs(ltl_to_taa(fpos, d)));
 	  auto aneg = scc_filter(spot::tgba_dupexp_dfs(ltl_to_taa(fneg, d)));
-	  auto ec = spot::couvreur99(spot::product(apos, aneg));
-	  auto res = ec->check();
-	  if (res)
+	  if (!spot::product(apos, aneg)->is_empty())
 	    {
 	      std::cerr << "non-empty intersection between pos and neg (TAA)\n";
 	      exit(2);
-	  }
-	  delete ec;
+	    }
 	}
       fpos->destroy();
       fneg->destroy();
diff --git a/src/tgbatest/complementation.cc b/src/tgbatest/complementation.cc
index cb5aa9a90..aa19c553c 100644
--- a/src/tgbatest/complementation.cc
+++ b/src/tgbatest/complementation.cc
@@ -274,8 +274,8 @@ int main(int argc, char* argv[])
       nAf = spot::make_kv_complement(Af);
       nAnf = spot::make_kv_complement(Anf);
     }
-    spot::emptiness_check* ec = spot::couvreur99(spot::product(nAf, nAnf));
-    spot::emptiness_check_result* res = ec->check();
+    auto ec = spot::couvreur99(spot::product(nAf, nAnf));
+    auto res = ec->check();
     spot::tgba_statistics a_size =  spot::stats_reachable(ec->automaton());
     std::cout << "States: "
               << a_size.states << std::endl
@@ -292,12 +292,8 @@ int main(int argc, char* argv[])
     else
       std::cout << "OK";
     std::cout << std::endl;
-
-    delete res;
-    delete ec;
     nf1->destroy();
     f1->destroy();
-
   }
 
   return return_value;
diff --git a/src/tgbatest/emptchk.cc b/src/tgbatest/emptchk.cc
index 1a1f70256..8176e68dc 100644
--- a/src/tgbatest/emptchk.cc
+++ b/src/tgbatest/emptchk.cc
@@ -122,7 +122,7 @@ main(int argc, char** argv)
       for (auto& algo: algos)
 	{
 	  const char* err;
-	  auto i = spot::emptiness_check_instantiator::construct(algo, &err);
+	  auto i = spot::make_emptiness_check_instantiator(algo, &err);
 	  if (!i)
 	    {
 	      std::cerr << "Failed to parse `" << err <<  '\'' << std::endl;
@@ -157,17 +157,14 @@ main(int argc, char** argv)
 	      int ce_found = 0;
 	      do
 		{
-		  auto res = ec->check();
-		  if (res)
+		  if (auto res = ec->check())
 		    {
 		      ++ce_found;
 		      std::cout << ce_found << " counterexample found\n";
-                      auto run = res->accepting_run();
-		      if (run)
+		      if (auto run = res->accepting_run())
 			{
 			  auto ar = spot::tgba_run_to_tgba(a, run);
 			  spot::dotty_reachable(std::cout, ar, false);
-			  delete run;
 			}
 		      std::cout << '\n';
 		      if (runs == 0)
@@ -175,7 +172,6 @@ main(int argc, char** argv)
 			  std::cerr << "ERROR: Expected no counterexample.\n";
 			  exit(1);
 			}
-		      delete res;
 		    }
 		  else
 		    {
@@ -201,10 +197,7 @@ main(int argc, char** argv)
 		  std::cerr << "ERROR: expected a counterexample.\n";
 		  exit(1);
 		}
-
-	      delete ec;
 	    }
-	  delete i;
 	}
       f->destroy();
     }
diff --git a/src/tgbatest/ltl2tgba.cc b/src/tgbatest/ltl2tgba.cc
index 46ca0c17c..6ccec85a4 100644
--- a/src/tgbatest/ltl2tgba.cc
+++ b/src/tgbatest/ltl2tgba.cc
@@ -354,7 +354,7 @@ checked_main(int argc, char** argv)
   int output = 0;
   int formula_index = 0;
   const char* echeck_algo = 0;
-  spot::emptiness_check_instantiator* echeck_inst = 0;
+  spot::emptiness_check_instantiator_ptr echeck_inst = 0;
   enum { NoneDup, BFS, DFS } dupexp = NoneDup;
   bool expect_counter_example = false;
   bool accepting_run = false;
@@ -500,7 +500,7 @@ checked_main(int argc, char** argv)
 
 	  const char* err;
 	  echeck_inst =
-	    spot::emptiness_check_instantiator::construct(echeck_algo, &err);
+	    spot::make_emptiness_check_instantiator(echeck_algo, &err);
 	  if (!echeck_inst)
 	    {
 	      std::cerr << "Failed to parse argument of -e near `"
@@ -518,7 +518,7 @@ checked_main(int argc, char** argv)
 
 	  const char* err;
 	  echeck_inst =
-	    spot::emptiness_check_instantiator::construct(echeck_algo, &err);
+	    spot::make_emptiness_check_instantiator(echeck_algo, &err);
 	  if (!echeck_inst)
 	    {
 	      std::cerr << "Failed to parse argument of -e near `"
@@ -1713,13 +1713,13 @@ checked_main(int argc, char** argv)
 
       if (echeck_inst)
 	{
-	  spot::emptiness_check* ec = echeck_inst->instantiate(a);
+	  auto ec = echeck_inst->instantiate(a);
 	  bool search_many = echeck_inst->options().get("repeated");
 	  assert(ec);
 	  do
 	    {
 	      tm.start("running emptiness check");
-	      spot::emptiness_check_result* res = ec->check();
+	      auto res = ec->check();
 	      tm.stop("running emptiness check");
 
               if (paper_opt)
@@ -1736,8 +1736,7 @@ checked_main(int argc, char** argv)
                   std::cout <<
                             ec->automaton()->number_of_acceptance_conditions()
                             << ", ";
-                  const spot::ec_statistics* ecs =
-                        dynamic_cast<const spot::ec_statistics*>(ec);
+		  auto ecs = ec->emptiness_check_statistics();
                   if (ecs)
                     std::cout << std::right << std::setw(10)
                               << ecs->states() << ", "
@@ -1781,7 +1780,7 @@ checked_main(int argc, char** argv)
                     {
 
 		      tm.start("computing accepting run");
-                      spot::tgba_run* run = res->accepting_run();
+                      auto run = res->accepting_run();
 		      tm.stop("computing accepting run");
 
                       if (!run)
@@ -1793,11 +1792,8 @@ checked_main(int argc, char** argv)
                           if (opt_reduce)
                             {
 			      tm.start("reducing accepting run");
-                              spot::tgba_run* redrun =
-                                spot::reduce_run(res->automaton(), run);
+                              run = spot::reduce_run(res->automaton(), run);
 			      tm.stop("reducing accepting run");
-                              delete run;
-                              run = redrun;
                             }
 			  if (accepting_run_replay)
 			    {
@@ -1827,7 +1823,6 @@ checked_main(int argc, char** argv)
 				}
 			      tm.stop("printing accepting run");
 			    }
-			  delete run;
                         }
                     }
 		  else
@@ -1836,14 +1831,11 @@ checked_main(int argc, char** argv)
 				<< "(use -C to print it)" << std::endl;
 		    }
                 }
-	      delete res;
 	    }
 	  while (search_many);
-	  delete ec;
 	}
       if (f)
         f->destroy();
-      delete echeck_inst;
     }
   else
     {
diff --git a/src/tgbatest/randtgba.cc b/src/tgbatest/randtgba.cc
index 29134e635..7150eb976 100644
--- a/src/tgbatest/randtgba.cc
+++ b/src/tgbatest/randtgba.cc
@@ -59,7 +59,7 @@
 struct ec_algo
 {
   std::string name;
-  spot::emptiness_check_instantiator* inst;
+  spot::emptiness_check_instantiator_ptr inst;
 };
 
 const char* default_algos[] = {
@@ -84,12 +84,12 @@ const char* default_algos[] = {
 
 std::vector<ec_algo> ec_algos;
 
-spot::emptiness_check*
+spot::emptiness_check_ptr
 cons_emptiness_check(int num, spot::const_tgba_ptr a,
 		     const spot::const_tgba_ptr& degen,
 		     unsigned int n_acc)
 {
-  spot::emptiness_check_instantiator* inst = ec_algos[num].inst;
+  auto inst = ec_algos[num].inst;
   if (n_acc < inst->min_acceptance_conditions()
       || n_acc > inst->max_acceptance_conditions())
     a = degen;
@@ -380,7 +380,7 @@ struct ar_stat
   }
 
   void
-  count(const spot::tgba_run* run)
+  count(const spot::const_tgba_run_ptr& run)
   {
     int p = run->prefix.size();
     int c = run->cycle.size();
@@ -837,9 +837,8 @@ main(int argc, char** argv)
 	{
 	  const char* err;
 	  ec_algos[i].inst =
-	    spot::emptiness_check_instantiator::construct(ec_algos[i]
-							  .name.c_str(),
-							  &err);
+	    spot::make_emptiness_check_instantiator(ec_algos[i].name.c_str(),
+						    &err);
 	  if (ec_algos[i].inst == 0)
 	    {
 	      std::cerr << "Parse error after `" << err << '\'' << std::endl;
@@ -939,9 +938,7 @@ main(int argc, char** argv)
 
 		  for (int i = 0; i < n_alg; ++i)
 		    {
-		      spot::emptiness_check* ec;
-		      spot::emptiness_check_result* res;
-		      ec = cons_emptiness_check(i, a, degen, real_n_acc);
+		      auto ec = cons_emptiness_check(i, a, degen, real_n_acc);
 		      if (!ec)
 			continue;
 		      ++n_ec;
@@ -952,17 +949,16 @@ main(int argc, char** argv)
 			  std::cout << algo << ": ";
 			}
 		      tm_ec.start(algo);
+		      spot::emptiness_check_result_ptr res;
 		      for (int count = opt_R;;)
 			{
 			  res = ec->check();
 			  if (count-- <= 0)
 			    break;
-			  delete res;
-			  delete ec;
 			  ec = cons_emptiness_check(i, a, degen, real_n_acc);
 			}
 		      tm_ec.stop(algo);
-		      const spot::unsigned_statistics* ecs = ec->statistics();
+		      auto ecs = ec->statistics();
 		      if (opt_z && res)
 			{
 			  // Notice that ratios are computed w.r.t. the
@@ -1001,7 +997,7 @@ main(int argc, char** argv)
 			  ++n_non_empty;
 			  if (opt_replay)
 			    {
-			      spot::tgba_run* run;
+			      spot::tgba_run_ptr run;
 			      bool done = false;
 			      tm_ar.start(algo);
 			      for (int count = opt_R;;)
@@ -1030,7 +1026,6 @@ main(int argc, char** argv)
 
 				  if (count-- <= 0 || !run)
 				    break;
-				  delete run;
 				}
 			      if (!run)
 				{
@@ -1065,7 +1060,7 @@ main(int argc, char** argv)
 
 				  if (opt_reduce)
 				    {
-				      spot::tgba_run* redrun =
+				      auto redrun =
 					spot::reduce_run(res->automaton(), run);
 				      if (!spot::replay_tgba_run(s,
 								 res
@@ -1093,14 +1088,11 @@ main(int argc, char** argv)
 						    << redrun->cycle.size()
 						    << ']';
 					}
-				      delete redrun;
 				    }
-				  delete run;
 				}
 			    }
 			  if (!opt_paper)
 			    std::cout << std::endl;
-			  delete res;
 			}
 		      else
 			{
@@ -1122,7 +1114,6 @@ main(int argc, char** argv)
 
 		      if (opt_Z && !opt_paper)
 			ec->print_stats(std::cout);
-		      delete ec;
 		    }
 
 		  assert(n_empty + n_non_empty + n_maybe_empty == n_ec);
@@ -1310,10 +1301,6 @@ main(int argc, char** argv)
       delete formula_file;
     }
 
-  if (opt_ec)
-    for (unsigned i = 0; i < ec_algos.size(); ++i)
-      delete ec_algos[i].inst;
-
   delete ap;
   delete apf;
   return exit_code;
diff --git a/wrap/python/ajax/spot.in b/wrap/python/ajax/spot.in
index 6d77fa918..6877b47c6 100755
--- a/wrap/python/ajax/spot.in
+++ b/wrap/python/ajax/spot.in
@@ -102,7 +102,6 @@ if not script:
     httpd.serve_forever()
 
 import cgi
-import cgitb; cgitb.enable()
 import signal
 import time
 import os.path
@@ -120,6 +119,9 @@ sys.stdout = os.fdopen(sys.stdout.fileno(), "wb", 0)
 # even errors from subprocesses get printed).
 os.dup2(sys.stdout.fileno(), sys.stderr.fileno())
 
+import cgitb
+sys.excepthook = cgitb.Hook(file=sys.stderr)
+
 # Create the temporary cache directory
 os.mkdir(tmpdir, 493) # See comment above about 0o755 or 0755.
 
@@ -533,7 +535,7 @@ elif translator == 'ta':
     refined_rules = False
     if form.getfirst('ta', '') == 'lc':
         refined_rules = True
-    automaton = spot.ltl_to_taa(f, dict, refined_rules)
+    automaton = spot.tgba_dupexp_dfs(spot.ltl_to_taa(f, dict, refined_rules))
 elif translator == 'l3':
     l3out = '-T'
     l3opt = { '-l', '-P', '-A', '-c', '-C', '-o', '-p' }
@@ -770,7 +772,7 @@ if output_type == 'r':
     err = ""
     opt = (form.getfirst('ec', 'Cou99') + "(" +
            form.getfirst('eo', '') + ")")
-    eci, err = spot.emptiness_check_instantiator.construct(opt)
+    eci, err = spot.make_emptiness_check_instantiator(opt)
 
     if not eci:
         unbufprint('<div class="parse-error">Cannot parse "' + opt
@@ -824,8 +826,4 @@ if output_type == 'r':
                 del ec_run
             del ec_res
             unbufprint('</div>')
-        del ec
-        del ec_a
-    degen = 0
-    automaton = 0
     finish()
diff --git a/wrap/python/spot.i b/wrap/python/spot.i
index a4483cb52..ed3c4eb42 100644
--- a/wrap/python/spot.i
+++ b/wrap/python/spot.i
@@ -36,7 +36,6 @@
  // sed 's/.*<\(.*\)>.*/%shared_ptr(spot::\1)/g'
 %shared_ptr(spot::bdd_dict)
 %shared_ptr(spot::dstar_aut)
-%shared_ptr(spot::dstar_aut)
 %shared_ptr(spot::future_conditions_collector)
 %shared_ptr(spot::kripke)
 %shared_ptr(spot::saba)
@@ -56,6 +55,10 @@
 %shared_ptr(spot::tgba_sgba_proxy)
 %shared_ptr(spot::tgta)
 %shared_ptr(spot::tgta_explicit)
+%shared_ptr(spot::tgba_run)
+%shared_ptr(spot::emptiness_check)
+%shared_ptr(spot::emptiness_check_result)
+%shared_ptr(spot::emptiness_check_instantiator)
 
 namespace std {
    %template(liststr) list<string>;
@@ -203,19 +206,8 @@ using namespace spot;
 %include "ltlvisit/simplify.hh"
 %include "ltlvisit/tostring.hh"
 %include "ltlvisit/tunabbrev.hh"
-%include "ltlvisit/apcollect.hh"
 %include "ltlvisit/lbt.hh"
 
-%feature("new") spot::emptiness_check::check;
-%feature("new") spot::emptiness_check_instantiator::construct;
-%feature("new") spot::emptiness_check_instantiator::instanciate;
-%feature("new") spot::emptiness_check_result::accepting_run;
-%feature("new") spot::explicit_magic_search;
-%feature("new") spot::explicit_se05_search;
-%feature("new") spot::tgba::get_init_state;
-%feature("new") spot::tgba::succ_iter;
-%feature("new") spot::tgba_succ_iterator::current_state;
-
 // Help SWIG with namespace lookups.
 #define ltl spot::ltl
 %include "tgba/bddprint.hh"
@@ -232,6 +224,9 @@ namespace spot {
   };
 }
 
+// Should come after the definition of tgba_digraph
+%include "ltlvisit/apcollect.hh"
+
 %include "tgbaalgos/degen.hh"
 %include "tgbaalgos/dottydec.hh"
 %include "tgbaalgos/dotty.hh"