Julia Pevtsova, IAS

Support cones for infinitesimal group schemes.
Abstract: We verify that the construction of {\it support cone} 
for infinite dimensional modules, introduced in \cite{P}, extends 
to modules over any infinitesimal group scheme and satisfies all
good properties of support varieties for finite dimensional modules,
thereby extending the results of the author for infinite dimensional 
modules of Frobenius kernels \cite{P}. We show,  using an alternative 
description of support cones in terms of Rickard idempotents, that for 
an algebraic group $G$ over an algebraically closed field $k$ of positive
characteristic $p$ and a point $s$ in the cohomological support variety 
of a Frobenius kernel $\Gr$, the orbit $G\cdot s$ can be realized as a 
support cone of a rational $G$-module.

Preprint 2002