proposition: Fact ratzN : {morph ratz : x / - x >-> oppq x}.
proof: Proof. by move=> x /=; rewrite !ratz_frac // /add /= !mulr1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg countalg div ssrnum) mathcomp(ssrint prime archimedean)