\title{Generic idempotent modules for a finite group}
\author{D. J. Benson}
\address{Department of Mathematics, University of Georgia, Athens GA 30602, USA}
\thanks{The first author is partly supported by a grant from the NSF}
\author{H. Krause}
\address{Fakult\"at f\"ur Mathematik, Universit\"at Bielefeld, 33501 Bielefeld,
Germany}
\date{\today}

\begin{abstract}
Let $G$ be a finite group and $k$ an algebraically closed field of
characteristic $p$.
Let $F_\mathcal U$ be the Rickard idempotent $kG$-module corresponding
to the set $\mathcal U$ of subvarieties of the cohomology variety $V_G$ which
are not irreducible components. We show that $F_\mathcal U$ is a finite sum of
{\em generic modules\/} corresponding to the irreducible components of $V_G$.
In this context, a generic module is an indecomposable module of infinite length
over $kG$ but finite length as a module over its endomorphism ring.
\end{abstract}