+let any_label = QNameSet.complement (QNameSet.empty)
+
+let new_state () = State.make()
+
+let add_tr ast tr = ast.trans <- (SetT.add tr (ast.trans))
+
+let add_reco ast st = ast.reco <- (StateSet.add st (ast.reco))
+
+let add_selec ast st = ast.selec <- (StateSet.add st (ast.selec))
+
+let add_bot ast st = ast.bottom <- (StateSet.add st (ast.bottom))
+
+let add_top ast st = ast.top <- (StateSet.add st (ast.top))
+
+let top_states ast = StateSet.elements ast.top