(* OK, WITH expf_expf_L0_2_bis: *)

Lemma expf_L0_6:forall (m:fmap)(x y z t:dart),
inv_hmap (L m zero x y) -> exd m z ->
let x_1 := cA_1 m one x in
~ expf m x_1 y ->
~ expf m x_1 z -> ~ expf m y t -> expf m z t ->
expf (L m zero x y) z t.