proposition: Lemma BRopp_Q x: ratp x -> BRopp (BR_of_Q x) = BR_of_Q (BQopp x).
proof: Proof. move => xq. by rewrite /BRopp (Y_true (BR_of_Q_prop1 xq)) (BQ_of_R_prop2 xq). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)