Proof using.
intros.
unfold wonElection in *. do_bool.
omega.
Qed.

(* Specifications: *)
Lemma wonElection_no_dup_in :
forall l1 l2,
wonElection l1 = true ->
NoDup l1 ->
(forall x, In x l1 -> In x l2) ->
wonElection l2 = true.