Section Clifford.
Variables (gT : finGroupType) (G H : {group gT}).
Hypothesis nsHG : H <| G.
Variables (n : nat) (rG : mx_representation F G n).
Let sHG := normal_sub nsHG.
Let nHG := normal_norm nsHG.
Let rH := subg_repr rG sHG.

Lemma Clifford_hom x m (U : 'M_(m, n)) :
x \in 'C_G(H) -> (U <= dom_hom_mx rH (rG x))%MS.