proposition: Lemma mxsub_eq_rowsub m' f g : g =1 id -> @mxsub m' _ f g =1 rowsub f.
proof: Proof. exact: eq_mxsub. 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)