© 1997 by London Mathematical Society
© The London Mathematical Society
Idempotent Modules in the Stable Category
School of Mathematics, University of Bristol University Walk, Bristol BS8 1TW. E-mail address: J.Rickard{at}bristol.ac.uk
Received 10 January 1994. Revision received 10 June 1995.
Let G be a finite group and k be an algebraically closed field of prime characteristic. Corresponding to each closed homogeneous subvariety W of the maximal ideal spectrum of H*(G, k) we construct (usually infinite-dimensional) kG-modules E(W) and F(W) which are idempotent in the sense that E(W) and F(W) are isomorphic (up to projective summands) to E(W)
E(W) and F(W)
F(W) respectively. We study the properties of these modules, and as an application we use them to describe natural direct sum decompositions of modules in quotient categories.