(* THEN, BY TRANSFERT: *)

Lemma expf_B0_CS_2:forall (m:fmap)(x z t:dart),
inv_hmap m -> succ m zero x ->
let x0 := cA m zero x in
let xb0 := bottom m zero x in
~expf m x0 xb0 ->
(expf m xb0 z /\ expf m x0 t
\/ expf m xb0 t /\ expf m x0 z
\/ expf m z t)
-> expf (B m zero x) z t.