(* Sewing at dimension 1: *)

(* Specifications: *)
Lemma expf_planar_1: forall (m:fmap)(x y:dart),
inv_qhmap m -> planar m ->
prec_Lq m di1 x y -> let mc:= clos m in
expf mc x (A mc di0 y) ->
planar (L m di1 x y).