proposition: Lemma vec_mxK : cancel vec_mx mxvec.
proof: Proof. by move=> u; apply/rowP=> k; case/mxvec_indexP: k => i j; rewrite mxvecE mxE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)