(** * Empty map *)

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

Lemma split_find : forall m x y, bst m -> find y m = match X.compare y x with | LT _ => find y (split x m)#l | EQ _ => (split x m)#o | GT _ => find y (split x m)#r end.