Section Elt2.
(* A new section is necessary for previous definitions to work with different [elt], especially [MapsTo]... *)
Variable elt elt' : Type.
(** Specification of [map] *)
Hint Resolve map_lelistA : core.

Lemma map_sorted : forall (m: t elt)(Hm : sort (@ltk elt) m)(f:elt -> elt'),
sort (@ltk elt') (map f m).