proposition: Lemma lsubmxEsub : lsubmx = colsub (lshift _).
proof: Proof. by rewrite /lsubmx /mxsub !unlock. 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)