(*============================================================== NECESSARY CONDITIONS AND FULL PLANARITY CRITERIA ===============================================================*)
(* OK!:*)

Lemma expf_planar_rcp_0: forall (m:fmap)(x y:dart),
inv_hmap m -> prec_L m zero x y ->
planar (L m zero x y) ->
expf m (cA_1 m one x) y ->
planar m.