proposition: Lemma Gauss_gcdzr p m n : coprimez p m -> gcdz p (m * n) = gcdz p n.
proof: Proof. by rewrite /gcdz abszM => /Gauss_gcdr->. 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)