proposition: Lemma dvdr_mull c a b : a %| b -> a %| c * b.
proof: Proof. by case/dvdrP=> x ->; apply/dvdrP; exists (c * x); rewrite mulrA. Qed.
imports: HB(structures) Coq(ssreflect ssrfun ssrbool Arith.Wf_nat) mathcomp(eqtype ssrnat div seq path) mathcomp(ssralg fintype perm tuple choice generic_quotient) mathcomp(matrix bigop zmodp mxalgebra poly) stronglydiscrete