scc_map: fix computation of ap_set_of, and (indirectly) aprec_set_of

Reported by Étienne Renault.

* src/tgbaalgos/scc.cc (build_map): Update root_.frond().supp for all
transitions leaving the top state, not only those causing a merge.
* src/tgbaalgos/scc.hh (ap_set_of): Clarify documentation.
* src/tgbatest/kv.test: Add a test case.

src/tgbaalgos/scc.cc

-// Copyright (C) 2008, 2009, 2011 Laboratoire de Recherche et
-// Developpement de l'Epita.
+// -*- coding: utf-8 -*-
+// Copyright (C) 2008, 2009, 2011, 2012 Laboratoire de Recherche et
+// Développement de l'Epita.
 //
 // This file is part of Spot, a model checking library.
 //
@@ -212,6 +213,7 @@ namespace spot
 	  ++self_loops_;
 	bdd acc = succ->current_acceptance_conditions();
 	bdd cond = succ->current_condition();
+	root_.front().supp &= bdd_support(cond);
 	// ... and point the iterator to the next successor, for
 	// the next iteration.
 	succ->next();
@@ -268,7 +270,7 @@ namespace spot
 	succ_type succs;
 	cond_set conds;
 	conds.insert(cond);
-	bdd supp = bdd_support(cond);
+	bdd supp = bddtrue;
 	bdd all = aut_->all_acceptance_conditions();
 	bdd useful = conv.as_full_product(acc);
 	while (threshold > root_.front().index)

src/tgbaalgos/scc.hh

-// Copyright (C) 2008, 2009, 2010, 2011 Laboratoire de Recherche et
-// Developpement de l'Epita.
+// -*- coding: utf-8 -*-
+// Copyright (C) 2008, 2009, 2010, 2011, 2012 Laboratoire de Recherche
+// et Développement de l'Epita.
 //
 // This file is part of Spot, a model checking library.
 //
@@ -122,10 +123,14 @@ namespace spot
     /// \pre This should only be called once build_map() has run.
     const cond_set& cond_set_of(unsigned n) const;
 
-    /// \brief Return the set of atomic properties occurring in an SCC.
+    /// \brief Return the set of atomic properties occurring on the
+    /// transitions leaving states from SCC \a n.
+    ///
+    /// The transitions considered are all transitions inside SCC
+    /// \a n, as well as the transitions leaving SCC \a n.
     ///
     /// \return a BDD that is a conjuction of all atomic properties
-    /// occurring on the transitions in the SCC n.
+    /// occurring on the transitions leaving the states of SCC \a n.
     ///
     /// \pre This should only be called once build_map() has run.
     bdd ap_set_of(unsigned n) const;

src/tgbatest/kv.test

 #!/bin/sh
-# Copyright (C) 2009, 2010, 2011 Laboratoire de Recherche et
-# Development de l'EPITA.
+# -*- coding: utf-8 -*-
+# Copyright (C) 2009, 2010, 2011, 2012 Laboratoire de Recherche et
+# Développement de l'EPITA.
 #
 # This file is part of Spot, a model checking library.
 #
@@ -40,3 +41,14 @@ check '((Xp2)U(X(1)))&(p1 R(p2 R p0))'
 
 # Make sure escaped variables print OK.
 check '"G1"U"GG" && "FF"'
+
+
+# Make sure we count 4 atomic propositions in
+# G("P_1.p2" <-> (F"P_1.p3" & ("P_0.p3" | (X"P_1.CS" U "P_1.p2")))) U G"P_1.p2"
+# even after iterated simulation
+# Report from Etienne Renault.
+
+../ltl2tgba -KV -R3 -RIS >out \
+'G("P_1.p2" <-> (F"P_1.p3" & ("P_0.p3" | (X"P_1.CS" U "P_1.p2")))) U G"P_1.p2"'
+x=`sed -n '/APre/{s/.*APrec=\[\([^]]*\)\].*/\1/p;q}' out | tr ' ' '\n' | wc -l`
+test "$x" = 4