proposition: Lemma dvdC_mull x y z : y \in Num.int -> (x %| z)%C -> (x %| y * z)%C.
proof: Proof. move=> Zy /dvdCP[m Zm ->]; apply/dvdCP. by exists (y * m); rewrite ?mulrA ?rpredM. 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)