End ext_subst_sig.
(**************** Ext invert ****************)
Module Type ext_invert_sig.
Include ext_subst_sig.
(* ---------- inversion lemmas ---------------- *)

Axiom invert_a_Const : forall G T A,
Typing G (a_Const T) A ->
exists B, DataTy B a_Star /\ DefEq G (dom G) A B  a_Star
/\ binds T (Cs B) toplevel.