proposition: Lemma dvdr_mulmxl m n p x (M : 'M[R]_(m,n)) (N : 'M[R]_(p,m)) : (forall i j, x %| M i j) -> forall i j, x %| (N *m M) i j.
proof: Proof. by move=> hM i j; rewrite !mxE; apply: big_dvdr=> k; rewrite dvdr_mull ?hM. 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