fact: Definition dvdmx m n k (M : 'M[R]_(m,n)) (N : 'M_(k, n)) := divmx N M *m M == N.
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