(** * Empty map *)

Definition Empty m := forall (a:key)(e:elt) , ~ MapsTo a e m.

Lemma remove_min_find : forall l x e r h y, bst (Node l x e r h) -> find y (Node l x e r h) = match X.compare y (remove_min l x e r)#2#1 with | LT _ => None | EQ _ => Some (remove_min l x e r)#2#2 | GT _ => find y (remove_min l x e r)#1 end.