(*===========================================================
                expe AND bottom
============================================================*)

(* expo and between in an edge: *)

Definition expe(m:fmap)(z t:dart):=
  MA0.expo m z t.Definition betweene(m:fmap)(z v t:dart):=
  MA0.between m z v t.

Lemma existi_dec:forall(m:fmap)(z v:dart)(k:nat), (exists i:nat, (i < k)%nat /\ Iter (MA0.f m) i z = v) \/ (~exists i:nat, (i < k)%nat /\ Iter (MA0.f m) i z = v).