Arguments set {A} {dom} x v m _.

(** [constant] **)
Lemma constant_OK_aux : forall A v (m : S.t A) l x,
S.In x (fold_left (λ (a : S.t A) (e : Dom.elt), S.add e v a) l m) <-> S.In x m ∨ InA X.eq x l.