(* THEN, THE RESULT: *)

Theorem expf_L1_eq:forall(m:fmap)(x y z t:dart),
let m1:= L m one x y in
let y0:= cA m zero y in
inv_hmap m1 -> ~expf m x y0
-> ~expf m x z -> ~expf m y0 z ->
(expf m1 z t <-> expf m z t).