proposition: Lemma BQdiv_square a b: ratp a -> ratp b -> BQsquare (a /q b) = (BQsquare a) /q (BQsquare b).
proof: Proof. move => aq bq; rewrite /BQsquare /BQdiv. move: (QS_inv bq) => ibq. rewrite (BQprod_ACA aq ibq aq ibq). by rewrite (BQprod_inv bq bq). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)