Module unique := fc_unique wf subst.
Set Bullet Behavior "Strict Subproofs".
Set Implicit Arguments.
(* This version is just for "head reduction." *)
intros.
unfold open_tm_wrt_tm. simpl. auto.
Qed.

Lemma open_a_Conv_co : forall a b g,
open_tm_wrt_co (a_Conv a g) b =
a_Conv (open_tm_wrt_co a b) (open_co_wrt_co g b).