proposition: Lemma dvdNmx m0 m1 m2 (M : 'M[R]_(m0,m1)) (N : 'M[R]_(m2,m1)) : (- M %| N) = (M %| N).
proof: Proof. by apply/dvdmxP/dvdmxP=> [] [X ->]; exists (- X); rewrite mulmxN mulNmx ?opprK. 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