(** Addition *)
Notation plus := Nat.add (only parsing).
Infix "+" := Nat.add : nat_scope.
Definition f_equal2_plus := f_equal2 plus.
Definition f_equal2_nat := f_equal2 (A1:=nat) (A2:=nat).
#[global]
Hint Resolve f_equal2_nat: core.

(* Specifications: *)
Lemma plus_n_O : forall n:nat, n = n + 0.
#[global]
Remove Hints eq_refl : core.