Section ListOfDomDef.
Variable A : Type.
Definition ad_list_of_dom :=
MapFold A (list ad) nil (app (A:=ad)) (fun (a:ad) (_:A) => a :: nil).

Lemma ad_list_of_dom_card_1 :
forall (m:Map A) (pf:ad -> ad),
length
(MapFold1 A (list ad) nil (app (A:=ad)) (fun (a:ad) (_:A) => a :: nil)
pf m) = MapCard A m.