(* THEN, COROLLARY: *)

(* Specifications: *)
Theorem degree_sum_bound: forall(m:fmap)(x y:dart),
inv_hmap m -> exd m x -> exd m y -> ~expo m x y ->
degree m x + degree m y <= ndN m.
Lemma expf_B0_CS_1_c:forall (m:fmap)(x z t:dart),
inv_hmap m -> succ m zero x ->
let x0 := cA m zero x in
let xb0 := bottom m zero x in
let x_1 := cA_1 m one x in
expf m x0 xb0 ->
(~ expf m x_1 z /\ expf m z t)
-> expf (B m zero x) z t.