apply clos_refl_trans_sound.
apply ctxt_sound; simpl in |- *; auto 10 with arith pts.
Qed.

(* Specifications: *)
Lemma sound_wf_type_cumul :
forall (e : env) (T U : term),
wf_type cts_pts_functor e T ->
red hdr e T U -> wf_type cts_pts_functor e U.