(* Specialization of results about lists modulo. *)
Notation In:=(InA eq).
Notation Inf:=(lelistA lt).
Notation Sort:=(sort lt).
Notation NoDup:=(NoDupA eq).

(* ltk ignore the second components *)
Lemma ltk_right_r : forall x k e e', ltk x (k,e) -> ltk x (k,e').