Hint Rewrite local_lift2_and : norm2.

(* Specifications: *)
Lemma subst_TT {A}{NA: NatDed A}: forall i v, subst i v TT = TT.
Lemma subst_FF {A}{NA: NatDed A}: forall i v, subst i v FF = FF.
Hint Rewrite @subst_TT @subst_FF: subst.