On group invariants determined by modular group algebras: even versus odd characteristic

Abstract

Let $p$ be a an odd prime and let $G$ be a finite $p$-group with cyclic commutator subgroup $G^{\prime }$. We prove that the exponent and the abelianization of the centralizer of $G^{\prime }$ in $G$ are determined by the group algebra of $G$ over any field of characteristic $p$. If, additionally, $G$ is $2$-generated then almost all the numerical invariants determining $G$ up to isomorphism are determined by the same group algebras; as a consequence the isomorphism type of the centralizer of $G^{\prime }$ is determined. These claims are known to be false for $p=2$.

18 pages