proposition: Fact Crat_divring_closed : divring_closed Crat.
proof: Proof. split=> // _ _ /CratP[x ->] /CratP[y ->]. by rewrite -rmorphB Crat_rat. by rewrite -fmorph_div Crat_rat. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun ssrnat eqtype seq choice) mathcomp(div fintype path bigop finset prime order ssralg) mathcomp(poly polydiv mxpoly generic_quotient countalg) mathcomp(ssrnum closed_field ssrint archimedean rat intdiv) mathcomp(algebraics_fundamentals)