+let mk_constructor j = function
+ | Ref (d, u, Ind (_,i)) ->
+ reference_of_string (string_of_reference (Ref (d, u, Con (i,j))))
+ | _ -> assert false
+;;
+
+let mk_fix i j = function
+ | Ref (d, u, Fix _) ->
+ reference_of_string (string_of_reference (Ref (d, u, Fix (i,j))))
+ | _ -> assert false
+;;
+
+let mk_cofix i = function
+ | Ref (d, u, CoFix _) ->
+ reference_of_string (string_of_reference (Ref (d, u, CoFix i)))
+ | _ -> assert false
+;;
+