(* planar_Br: IN THE FOLLOWING *)
(* OK: *)

(* Specifications: *)
Lemma not_succ_Br1_fst:forall(m:fmap)(x x':dart),
inv_hmap m -> ~succ (Br1 m x x') zero x.
Lemma not_succ_Br1_snd:forall(m:fmap)(x x':dart),
inv_hmap m ->
~succ (Br1 m x x') zero x'.