proposition: Lemma mulz_gcdl m n p : gcdz m n * `|p|%:Z = gcdz (m * p) (n * p).
proof: Proof. by rewrite -PoszM muln_gcdl -!abszM. 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)