proposition: Lemma Gauss_gcdzl p m n : coprimez p n -> gcdz p (m * n) = gcdz p m.
proof: Proof. by move=> co_pn; rewrite mulrC Gauss_gcdzr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime order) mathcomp(ssralg poly ssrnum ssrint archimedean rat matrix) mathcomp(polydiv perm zmodp mxalgebra vector)