Hint Resolve closed_wrt_tc_Zle : closed.

(* Specifications: *)
Lemma closed_wrt_replace_nth:
forall {B} S n R (R1: environ -> B),
closed_wrt_vars S R1 ->
Forall (closed_wrt_vars S) R ->
Forall (closed_wrt_vars S) (replace_nth n R R1).