diff --git a/ChangeLog b/ChangeLog
index c13167507..2fa25bc47 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2006-02-15  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* iface/gspn/ltlgspn.cc, src/tgbaalgos/gtec/gtec.cc,
+	src/tgbaalgos/gtec/gtec.hh: New option (-e6) to disable
+	inclusion check in the stack.
+
 	* src/tgbaalgos/gtec/gtec.cc, src/tgbaalgos/gtec/gtec.hh:
 	Count the number of removed components.
 
diff --git a/iface/gspn/ltlgspn.cc b/iface/gspn/ltlgspn.cc
index eb0bb1031..0464e0309 100644
--- a/iface/gspn/ltlgspn.cc
+++ b/iface/gspn/ltlgspn.cc
@@ -73,6 +73,8 @@ syntax(char* prog)
 	    << std::endl
 	    << "  -e5 use d. incl. Couvreur's emptiness-check's shy variant"
 	    << std::endl
+	    << "  -e6 like -e5, but without inclusion checks in the "
+	    << "search stack" << std::endl
 #endif
 	    << "  -m  degeneralize and perform a magic-search" << std::endl
 	    << std::endl
@@ -105,6 +107,7 @@ main(int argc, char **argv)
       bool proj = true;
 #ifdef SSP
       bool doublehash = true;
+      bool stack_inclusion = true;
 #endif
       std::string dead = "true";
 
@@ -155,6 +158,11 @@ main(int argc, char **argv)
 	    {
 	      check = Couvreur5;
 	    }
+	  else if (!strcmp(argv[formula_index], "-e6"))
+	    {
+	      check = Couvreur5;
+	      stack_inclusion = false;
+	    }
 #endif
 	  else if (!strcmp(argv[formula_index], "-m"))
 	    {
@@ -260,7 +268,7 @@ main(int argc, char **argv)
 		ec = spot::couvreur99_check_ssp_shy_semi(prod);
 		break;
 	      case Couvreur5:
-		ec = spot::couvreur99_check_ssp_shy(prod);
+		ec = spot::couvreur99_check_ssp_shy(prod, stack_inclusion);
 		break;
 #endif
 	      default:
diff --git a/iface/gspn/ssp.cc b/iface/gspn/ssp.cc
index 2fd4335e3..e5e6b0db5 100644
--- a/iface/gspn/ssp.cc
+++ b/iface/gspn/ssp.cc
@@ -973,12 +973,13 @@ namespace spot
   class couvreur99_check_shy_ssp : public couvreur99_check_shy
   {
   public:
-    couvreur99_check_shy_ssp(const tgba* a)
+    couvreur99_check_shy_ssp(const tgba* a, bool stack_inclusion)
       : couvreur99_check_shy(a,
 			     option_map(),
 			     numbered_state_heap_ssp_factory_semi::instance()),
 	inclusion_count_heap(0),
-	inclusion_count_stack(0)
+	inclusion_count_stack(0),
+	stack_inclusion(stack_inclusion)
     {
       stats["inclusion count heap"] =
 	static_cast<spot::unsigned_statistics::unsigned_fun>
@@ -994,6 +995,7 @@ namespace spot
   private:
     unsigned inclusion_count_heap;
     unsigned inclusion_count_stack;
+    bool stack_inclusion;
 
   protected:
     unsigned
@@ -1064,8 +1066,9 @@ namespace spot
 			}
 		      else
 			{
-			  if (spot_inclusion(old_state->left(),
-					     new_state->left()))
+			  if (stack_inclusion
+			      && spot_inclusion(old_state->left(),
+						new_state->left()))
 			    {
 			      ++inclusion_count_stack;
 
@@ -1197,10 +1200,10 @@ namespace spot
   }
 
   couvreur99_check*
-  couvreur99_check_ssp_shy(const tgba* ssp_automata)
+  couvreur99_check_ssp_shy(const tgba* ssp_automata, bool stack_inclusion)
   {
     assert(dynamic_cast<const tgba_gspn_ssp*>(ssp_automata));
-    return new couvreur99_check_shy_ssp(ssp_automata);
+    return new couvreur99_check_shy_ssp(ssp_automata, stack_inclusion);
   }
 
 #if 0
diff --git a/iface/gspn/ssp.hh b/iface/gspn/ssp.hh
index f32411019..f9f12fa09 100644
--- a/iface/gspn/ssp.hh
+++ b/iface/gspn/ssp.hh
@@ -54,7 +54,8 @@ namespace spot
   /// @{
   couvreur99_check* couvreur99_check_ssp_semi(const tgba* ssp_automata);
   couvreur99_check* couvreur99_check_ssp_shy_semi(const tgba* ssp_automata);
-  couvreur99_check* couvreur99_check_ssp_shy(const tgba* ssp_automata);
+  couvreur99_check* couvreur99_check_ssp_shy(const tgba* ssp_automata,
+					     bool stack_inclusion = true);
 
   /// @}