(*Realizer [n:nat][e:env]Cases (list_item ? e n) of (inleft (Ax T)) => (inright term) | (inleft (Def d T)) => (inleft term (lift (S n) d)) | _ => (inright term) end. *)
intros.
case (list_item e n); [ intros ([T| d T], is_dcl) | intros ].
right; red in |- *; intros.
inversion_clear H.
absurd (Ax T = Def d T0).
discriminate.
apply fun_item with e n; auto with arith pts.
left; exists (lift (S n) d).
apply delta_intro with T; auto with arith pts.
right; red in |- *; intros.
inversion_clear H.
elim n0 with (Def d T); auto with arith pts.
Qed.

(* Specifications: *)
Lemma sort_delta_norm : forall (e : env) (s : sort), normal delta e (Srt s).
red in |- *; red in |- *; intros.