intros.
apply red_trans with (Prod A' B).
elim H; simpl in |- *; intros; auto with pts.
apply red_trans with (Prod y B); auto with pts.
elim H0; intros; auto with pts.
apply red_trans with (Prod A' y); auto with pts.
Qed.

Lemma conv_conv_abs :
forall (e : env) (A A' M M' : term),
conv e A A' -> conv (Ax A' :: e) M M' -> conv e (Abs A M) (Abs A' M').