(* NEW FORMULATION!! *)

Lemma expf_expf_L0_4_bis_prel:forall(m:fmap)(x y z:dart),
inv_hmap (L m zero x y) ->
let x_1 := cA_1 m one x in
let y_0 := cA_1 m zero y in
let y_0_1 := cA_1 m one y_0 in
~ expf m x_1 y ->
expf m y_0_1 z ->
expf (L m zero x y) y_0_1 z.