Section RawGroupAction.
Variables (aT rT : finGroupType) (D : {set aT}) (R : {set rT}).
Variable to : groupAction D R.
Canonical gacent_group A := Group (group_set_gacent A).

Lemma astabM M N :
M \subset R -> N \subset R -> 'C(M * N | to) = 'C(M | to) :&: 'C(N | to).