(** Commutativity *)

(* Specifications: *)
Lemma orb_comm : forall b1 b2:bool, b1 || b2 = b2 || b1.
(** Associativity *)
Lemma orb_assoc : forall b1 b2 b3:bool, b1 || (b2 || b3) = b1 || b2 || b3.
#[global]
Hint Resolve orb_comm orb_assoc: bool.
Lemma andb_comm : forall b1 b2:bool, b1 && b2 = b2 && b1.
(** Associativity *)
Lemma andb_assoc : forall b1 b2 b3:bool, b1 && (b2 && b3) = b1 && b2 && b3.
#[global]
Hint Resolve andb_comm andb_assoc: bool.