proposition: Lemma dvdmxD m0 m1 m2 (M : 'M[R]_(m0,m1)) (N K : 'M[R]_(m2,m1)) : M %| N -> M %| K -> M %| N + K.
proof: Proof. by move=> /dvdmxP [X ->] /dvdmxP [Y ->]; rewrite -mulmxDl dvdmxMl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice matrix bigop zmodp mxalgebra poly) ssrcomplements dvdring stronglydiscrete