proposition: Lemma dvd_quot_mx x (X : 'M_(x, _)) : pres N %| X -> pres quot_by %| X.
proof: Proof. by move=> dvdNX; apply/dvd_col_mxP; exists 0; rewrite mul0mx subr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice matrix bigop zmodp mxalgebra poly) ssrcomplements stronglydiscrete coherent edr