red in |- *.
simple induction 1; simpl in |- *; intros.
rewrite distr_lift_subst; auto with arith pts.
red in |- *.
simple induction 1; simpl in |- *; intros.
rewrite distr_subst; auto with arith pts.
red in |- *; intros.
elim H; auto with arith pts.
Defined.

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