#[global]
Hint Resolve orb_false_intro: bool.

(* Specifications: *)
Lemma orb_false_elim :
forall b1 b2:bool, b1 || b2 = false -> b1 = false /\ b2 = false.
Lemma orb_diag : forall b, b || b = b.
(** [true] is a zero for [orb] *)
Lemma orb_true_r : forall b:bool, b || true = true.
#[global]
Hint Resolve orb_true_r: bool.
Lemma orb_true_l : forall b:bool, true || b = true.
Notation orb_b_true := orb_true_r (only parsing).