_imset //=; last exact/injmP.
apply: eq_bigr => y Gy; rewrite -morphJ //.
have [Hxy | H'xy] := boolP (x ^ y \in H); first by rewrite -eq_h

(* Specifications: *)
Proof. exact: raddfZnat. Qed.
Proof. exact: raddfZ_Cnat. Qed.
Proof. exact: raddfZ_Cint. Qed.
Proof. by move=> phi; apply/cfunP=> x; rewrite !cfunE /
Proof. exact: can_inj cfAutK. Qed.
have{sSuS} sSuS: {subset Su <= S} by move=> _
Qed.
Proof. exact: cforder_inj_rmorph cfAut_inj. Qed.
Qed.
by congr (_ * _); rewrite rmorph_sum; apply: eq_bigr => y; rewrite !cfunE.
Qed.