#[global]
Hint Resolve plus_n_O eq_refl: core.  (* We want eq_refl to have higher priority than plus_n_O *)

(* Specifications: *)
Lemma plus_O_n : forall n:nat, 0 + n = n.
Lemma plus_n_Sm : forall n m:nat, S (n + m) = n + S m.
#[global]
Hint Resolve plus_n_Sm: core.
Lemma plus_Sn_m : forall n m:nat, S n + m = S (n + m).
Notation plus_0_r_reverse := plus_n_O (only parsing).