(* A closed term is invariant under substitution. *)

(* Specifications: *)
Lemma closed_subst_invariant:
forall `{Lift T, Subst V T},
forall { _ : LiftLift},
forall { _ : SubstLift},
forall k t,
closed k t ->
forall j,
j >= k ->
forall v,
subst v j t = t.