(* ANCIENT FORMULATION : DIRECT FROM expf_expf_L0_4_bis_prel... *)

Lemma expf_expf_L0_4_bis:forall(m:fmap)(x y z:dart),
inv_hmap (L m zero x y) ->
let x_1 := cA_1 m one x in
~ expf m x_1 y ->
expf m y z ->
expf (L m zero x y) y z.