proposition: Lemma eqmx_rowsub_comp_perm (m1 m2 n : nat) (s : 'S_m2) f (A : 'M_(m1, n)) : (rowsub (f \o s) A :=: rowsub f A)%MS.
proof: Proof. rewrite rowsub_comp rowsubE; apply: eqmxMfull. by rewrite -perm_mxEsub row_full_unit unitmx_perm. 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)