(*==========================================================  TOPOLOGICAL FMAPS, HMAPS - WITH TAGS AND EMBEDDINGS  PART 6:.  PROPERTIES OF MERGING AND SPLITTING FACES expf / L1  COMPLETE: OK! ============================================================*)
(* Load Jordan1. Load Jordan2. Load Jordan3. Load Jordan4. Load Jordan5. *)
Require Export Jordan5.
(*========================================================== 1. MERGING FACES BY L1 (CASE ~expf m x y0) ===========================================================*)
(* CASE k = one IN cF_L (from Jordan5) : OK *)
(* 1. CASE ~expf m x y0: FACE MERGING *)
(* FIRST, SOME LEMMAS: *)
(* OK: *)
Open Scope nat_scope.
(* i-SUCCS OF x BY cF_L1, FOR i < DEG OF x, ARE INVARIANT: *)
(* OK: *)
(* i-SUCCS OF x BY cF_L1, FOR i < DEG x, DIFFER FROM x *)

Lemma diff_x_x10:forall(m:fmap)(x y:dart)(i:nat),
inv_hmap m -> prec_L m one x y ->
let y0 := cA m zero y in
let dx := MF.degree m x in
let m1:= L m one x y in
~expf m x y0 ->
0 < i <= dx - 1 ->
Iter (cF m1) i x <> x.