Published online by Cambridge University Press: 18 May 2009
In this note relations between the structure of a finite group G and ringtheoretical properties of the group algebra FG over a field F with characteristic p > 0 are investigated. Denoting by J(R) the Jacobson radical and by Z(R) the centre of the ring R, our aim is to prove the following theorem generalizing results of Wallace [10] and Spiegel [9]:
Theorem. Let G be a finite group and let F be an arbitrary field of characteristic p > 0. Denoting by BL the principal block ideal of the group algebra FG the following statements are equivalent:
(i) J(B1) ≤ Z(B1)
(ii) J(B1)is commutative,
(iii) G is p-nilpotent with abelian Sylowp-subgroups.