(* SUFFICIENT CONDITION: *)

Lemma expf_L1_II_CS:forall (m:fmap)(x y z t:dart),
inv_hmap (L m one x y) -> exd m z ->
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
expf m x y0 ->
( 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 ) ->
expf (L m one x y) z t.