proposition: Lemma dvdr_mul c d a b : a %| c -> b %| d -> a * b %| c * d.
proof: Proof. case/dvdrP=>x ->; case/dvdrP=> y ->. by rewrite -mulrCA; apply/dvdrP; exists (y * 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