proposition: Lemma eq_maxrowsub : (rowsub mxf A :=: A)%MS.
proof: Proof. apply/eqmxP; rewrite -(eq_leqif (mxrank_leqif_eq _))//. exact: maxrowsub_free. apply/row_subP => i; apply/submxP; exists (delta_mx 0 (mxf i)). by rewrite -rowE; apply/rowP => j; rewrite !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 finalg zmodp matrix)