Canonical Zchar_opprPred := OpprPred Zchar_zmod.
Canonical Zchar_addrPred := AddrPred Zchar_zmod.
Canonical Zchar_zmodPred := ZmodPred Zchar_zmod.

Lemma zchar_sub_irr S A :
{subset S <= 'Z[irr G]} -> {subset 'Z[S, A] <= 'Z[irr G, A]}.