(* RENAMING of MF.between: *)
Definition betweenf:= MF.between.

Lemma cF_L0_1:forall (m:fmap)(x y z:dart),
inv_hmap (L m zero x y) ->
let x_1 := cA_1 m one x in
betweenf m x_1 z y ->
cF (L m zero x y) z =
if eq_dart_dec y z then x_1 else cF m z.