(** * Conversions between lists and sets *)
Definition to_list := elements.

(* Specifications: *)
Lemma of_list_1 : forall l x, In x (of_list l) <-> InA E.eq x l.
Lemma of_list_2 : forall l, equivlistA E.eq (to_list (of_list l)) l.
Lemma of_list_3 : forall s, of_list (to_list s) [=] s.
Section Fold.
Lemma of_list_1 : forall l x, In x (of_list l) <-> InA E.eq x l.
Lemma of_list_2 : forall l, equivlistA E.eq (to_list (of_list l)) l.
Lemma of_list_3 : forall s, of_list (to_list s) [=] s.
Section Fold.