(* OK, USEFUL IN nc/B,L: *)

(* Specifications: *)
Lemma eqc_eqc_B : forall(m:fmap)(k:dim)(x z t:dart),
inv_hmap m -> succ m k x ->
eqc (B m k x) x (A m k x) ->
eqc m z t -> eqc (B m k x) z t.