Section RowGroup.
Variable n : nat.
Local Notation rVn := 'rV[F]_n.
Definition rowg m (A : 'M[F]_(m, n)) : {set rVn} := [set u | u <= A]%MS.
Canonical rowg_group m A := Group (@rowg_group_set m A).

Lemma rowgI m1 m2 (A : 'M_(m1, n)) (B : 'M_(m2, n)) :
rowg (A :&: B)%MS = rowg A :&: rowg B.