proposition: Lemma BRdiv_abs x y: realp x -> realp y -> (BRabs x) /r (BRabs y) = BRabs (x /r y).
proof: Proof. move => xr yr. by rewrite /BRdiv (BRprod_abs xr (RS_inv yr)) (BRinv_abs yr). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)