Section IrrConstt.
Variable (gT : finGroupType) (G H : {group gT}).
Definition irr_constt (B : {set gT}) phi := [pred i | '[phi, 'chi_i]_B != 0].

Lemma constt_ortho_char (phi psi : 'CF(G)) i j :
phi \is a character -> psi \is a character ->
i \in irr_constt phi -> j \in irr_constt psi ->
'[phi, psi] = 0 -> '['chi_i, 'chi_j] = 0.