(*=========================================================== cF, expf on L and B ============================================================*)
(* OK, TRIVIAL: USEFUL? *)

Lemma cA_I:forall(m:fmap)(k:dim)(x z:dart)(u:tag)(p:point),
inv_hmap m -> prec_I m x -> x <> z ->
(cA (I m x u p) k z = cA m k z).