(* Permutation matrix *)

Definition perm_mx n s : 'M_n := row_perm s 1%:M.Definition tperm_mx n i1 i2 : 'M_n := perm_mx (tperm i1 i2).

Lemma xcolE m n j1 j2 (A : 'M_(m, n)) : xcol j1 j2 A = A *m tperm_mx j1 j2.