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

Lemma neq0_has_constt (phi : 'CF(G)) :
phi != 0 -> exists i, i \in irr_constt phi.