Variable B : Type.
Variable eqB_dec : forall x y:B, { x=y }+{ ~x=y }.
(** Permutation is compatible with map. *)

(* Specifications: *)
Lemma permutation_map :
forall f l1 l2, permutation l1 l2 ->
PermutSetoid.permutation _ eqB_dec (map f l1) (map f l2).