(** ** Specifications written using equivalences *)
Section IffSpec.
Variable elt elt' elt'': Type.
Implicit Type m: t elt.
Implicit Type x y z: key.
Implicit Type e: elt.

Lemma elements_mapsto_iff : forall m x e,
MapsTo x e m <-> InA (@eq_key_elt _) (x,e) (elements m).