(* FINALLY, THE EXPECTED RESULT (OK): *)

(* Specifications: *)
Lemma between_bottom_B0_bis: forall(m:fmap)(x' x:dart),
inv_hmap m -> exd m x -> exd m x' -> x' <> x ->
let x0 := bottom m zero x in
let m0 := B m zero x' in
((betweene m x0 x' x ->
bottom m0 zero x = A m zero x')
/\ (~betweene m x0 x' x ->
bottom m0 zero x = bottom m zero x)).