Hint Resolve f_pred_precise f_pred_positive.

Lemma add_three : forall lr HT l (Hlr : Zlength lr = 3)
(Hhists : Forall (fun '(h, ls) => add_events [] [HAdd 1 1 (Znth 0 ls false); HAdd 2 1 (Znth 1 ls false);
HAdd 3 1 (Znth 2 ls false)] h) lr) (Hlens : Forall (fun '(_, ls) => Zlength ls = 3) lr)
(Hl : hist_list (concat (map fst lr)) l) (HHT : apply_hist empty_map l HT),
Zlength (filter id (concat (map snd lr))) = 3.