Definition cfclass (A : {set gT}) (phi : 'CF(A)) (B : {set gT}) :=
[seq (phi ^ repr Tx)%CF | Tx in rcosets 'I_B[phi] B].
Local Notation "phi ^: G" := (cfclass phi G) : cfun_scope.

(* This is Isaacs, Lemma (6.8). *)
Lemma dvdn_constt_Res1_irr1 i j :
H <| G -> j \in irr_constt ('Res[H, G] 'chi_i) ->
exists n, 'chi_i 1%g = n%:R * 'chi_j 1%g.