diff --git a/ChangeLog b/ChangeLog
index 087bbeba9..54ccc26d6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2011-02-04  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Add a way to count the number of sub-transitions.
+
+	* src/tgbaalgos/stats.hh (tgba_sub_statistics): New class.
+	(sub_stats_reachable): New function.
+	* src/tgbaalgos/stats.cc (sub_stats_bfs): New class.
+	(tgba_sub_statistics::dump, sub_stats_reachable): New function.
+	* src/tgbatest/ltl2tgba.cc (-kt): New option.
+	* src/tgbatest/ltl2tgba.test: Use -kt.
+
 2011-02-03  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	Read guard of the form !(x) in neverclaims.
diff --git a/src/tgbaalgos/stats.cc b/src/tgbaalgos/stats.cc
index dccdef772..5ac85f884 100644
--- a/src/tgbaalgos/stats.cc
+++ b/src/tgbaalgos/stats.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2008 Laboratoire de Recherche et Développement
+// Copyright (C) 2008, 2011 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 // Copyright (C) 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -54,6 +54,49 @@ namespace spot
     private:
       tgba_statistics& s_;
     };
+
+    class sub_stats_bfs: public stats_bfs
+    {
+    public:
+      sub_stats_bfs(const tgba* a, tgba_sub_statistics& s)
+	: stats_bfs(a, s), s_(s), seen_(bddtrue)
+      {
+      }
+
+      void
+      process_link(const state*, int, const state*, int,
+		   const tgba_succ_iterator* it)
+      {
+	++s_.transitions;
+
+	bdd cond = it->current_condition();
+	bdd newvars = bdd_exist(bdd_support(cond), seen_);
+	if (newvars != bddtrue)
+	  {
+	    seen_ &= newvars;
+	    int count = 0;
+	    while (newvars != bddtrue)
+	      {
+		++count;
+		newvars = bdd_high(newvars);
+	      }
+	    // If we discover one new variable, that means that all
+	    // transitions we counted so far are actually double
+	    // subtransitions.  If we have two new variables, they where
+	    // quadruple transitions, etc.
+	    s_.sub_transitions <<= count;
+	  }
+	while (cond != bddfalse)
+	  {
+	    cond -= bdd_satoneset(cond, seen_, bddtrue);
+	    ++s_.sub_transitions;
+	  }
+      }
+
+    private:
+      tgba_sub_statistics& s_;
+      bdd seen_;
+    };
   } // anonymous
 
 
@@ -64,12 +107,28 @@ namespace spot
     return out;
   }
 
+  std::ostream& tgba_sub_statistics::dump(std::ostream& out) const
+  {
+    out << "sub trans.: " << sub_transitions << std::endl;
+    this->tgba_statistics::dump(out);
+    return out;
+  }
+
   tgba_statistics
   stats_reachable(const tgba* g)
   {
-    tgba_statistics s = {0, 0};
+    tgba_statistics s;
     stats_bfs d(g, s);
     d.run();
     return s;
   }
+
+  tgba_sub_statistics
+  sub_stats_reachable(const tgba* g)
+  {
+    tgba_sub_statistics s;
+    sub_stats_bfs d(g, s);
+    d.run();
+    return s;
+  }
 }
diff --git a/src/tgbaalgos/stats.hh b/src/tgbaalgos/stats.hh
index 38383248d..dc2b0d6e2 100644
--- a/src/tgbaalgos/stats.hh
+++ b/src/tgbaalgos/stats.hh
@@ -1,4 +1,4 @@
-// Copyright (C) 2008 Laboratoire de Recherche et Développement
+// Copyright (C) 2008, 2011 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 // Copyright (C) 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -38,11 +38,22 @@ namespace spot
     unsigned transitions;
     unsigned states;
 
+    tgba_statistics() { transitions = 0; states = 0; }
+    std::ostream& dump(std::ostream& out) const;
+  };
+
+  struct tgba_sub_statistics: public tgba_statistics
+  {
+    unsigned sub_transitions;
+
+    tgba_sub_statistics() { sub_transitions = 0; }
     std::ostream& dump(std::ostream& out) const;
   };
 
   /// \brief Compute statistics for an automaton.
   tgba_statistics stats_reachable(const tgba* g);
+  /// \brief Compute subended statistics for an automaton.
+  tgba_sub_statistics sub_stats_reachable(const tgba* g);
 
   /// @}
 }
diff --git a/src/tgbatest/ltl2tgba.cc b/src/tgbatest/ltl2tgba.cc
index adf950cb0..676b7148a 100644
--- a/src/tgbatest/ltl2tgba.cc
+++ b/src/tgbatest/ltl2tgba.cc
@@ -259,6 +259,9 @@ syntax(char* prog)
 	    << std::endl
 	    << "  -ks   display statistics on the automaton (size only)"
 	    << std::endl
+	    << "  -kt   display statistics on the automaton (size + "
+	    << "subtransitions)"
+	    << std::endl
 	    << "  -K    dump the graph of SCCs in dot format" << std::endl
 	    << "  -KV   verbosely dump the graph of SCCs in dot format"
 	    << std::endl
@@ -486,6 +489,10 @@ main(int argc, char** argv)
 	{
 	  output = 12;
 	}
+      else if (!strcmp(argv[formula_index], "-kt"))
+	{
+	  output = 13;
+	}
       else if (!strcmp(argv[formula_index], "-K"))
 	{
 	  output = 10;
@@ -534,7 +541,7 @@ main(int argc, char** argv)
 	}
       else if (!strcmp(argv[formula_index], "-O"))
 	{
-	  output = 13;
+	  output = 14;
           opt_minimize = true;
 	}
       else if (!strcmp(argv[formula_index], "-p"))
@@ -1146,6 +1153,9 @@ main(int argc, char** argv)
 	      stats_reachable(a).dump(std::cout);
 	      break;
 	    case 13:
+	      sub_stats_reachable(a).dump(std::cout);
+	      break;
+	    case 14:
 	      if (minimized == 0)
 		{
 		  std::cout << "this is not an obligation property";
diff --git a/src/tgbatest/ltl2tgba.test b/src/tgbatest/ltl2tgba.test
index 515ec8704..326c219e6 100755
--- a/src/tgbatest/ltl2tgba.test
+++ b/src/tgbatest/ltl2tgba.test
@@ -63,7 +63,8 @@ done
 # Make sure '!(Ga U b)' has 3 states and 6 transitions,
 # before and after degeneralization.
 for opt in '' -D -DS; do
-  ../ltl2tgba -ks -f -R3 $opt '!(Ga U b)' > stdout
+  ../ltl2tgba -kt -f -R3 $opt '!(Ga U b)' > stdout
+  grep 'sub trans.: 11$' stdout
   grep 'transitions: 6$' stdout
   grep 'states: 3$' stdout
 done
@@ -71,7 +72,8 @@ done
 # Make sure 'Ga U b' has 4 states and 6 transitions,
 # before and after degeneralization.
 for opt in '' -D -DS; do
-  ../ltl2tgba -ks -f -R3 $opt 'Ga U b' > stdout
+  ../ltl2tgba -kt -f -R3 $opt 'Ga U b' > stdout
+  grep 'sub trans.: 12$' stdout
   grep 'transitions: 6$' stdout
   grep 'states: 4$' stdout
 done