#[global]
Hint Extern 5 (?X1 <> ?X2) => intro; discriminate: qarith.

(* Specifications: *)
Lemma Qcompare_antisym x y : CompOpp (x ?= y) = (y ?= x).
Lemma Qcompare_spec x y : CompareSpec (x==y) (x<y) (y<x) (x ?= y).
(** * Properties of equality. *)
Theorem Qeq_refl x : x == x.
Theorem Qeq_sym x y : x == y -> y == x.
Theorem Qeq_trans x y z : x == y -> y == z -> x == z.
#[global]
Hint Immediate Qeq_sym : qarith.