(* expf_L1_CNS is defined *)

Theorem expf_L1_CN:forall (m:fmap)(x y z t:dart),
inv_hmap (L m one x y) -> exd m z ->
expf (L m one x y) z t ->
let x1 := cA m one x in
let x10 := cA m zero x1 in
let y0 := cA m zero y in
let y_1 := cA_1 m one y in
if expf_dec m x y0
then betweenf m x z y0 /\ betweenf m x t y0
\/ betweenf m y_1 z x10 /\ betweenf m y_1 t x10
\/ ~ expf m x z /\ expf m z t
else   expf m z t
\/ expf m z x /\ expf m t y0
\/ expf m t x /\ expf m z y0.