(*========================================================== CHANGING THE OPENING IN AN ORBIT BY L_B: exd, inv_hmap, planar, cA, cA_1, bottom, cF, cF_1, top, expf, expe, eqc... ==========================================================*)
(* OK! *)

Lemma cA_L_B_top_bot:forall(m:fmap)(k:dim)(x z:dart),
inv_hmap m -> succ m k x ->
cA (L (B m k x) k (top m k x) (bottom m k x)) k z =
cA m k z.