(** uniset union *)

(* Specifications: *)
Lemma union_empty_left : forall x:uniset, seq x (union Emptyset x).
#[local]
Hint Resolve union_empty_left : core.
Lemma union_empty_right : forall x:uniset, seq x (union x Emptyset).
#[local]
Hint Resolve union_empty_right : core.
Lemma union_comm : forall x y:uniset, seq (union x y) (union y x).
#[local]
Hint Resolve union_comm : core.
Lemma union_ass :
forall x y z:uniset, seq (union (union x y) z) (union x (union y z)).