Frobenius Splitting of Equivariant Closures of Regular Conjugacy Classes
Institut for Matematiske Fag, Aarhus Universitet 8000 Århus C, Denmark funch{at}imf.au.dk
Received 6 June 2005. Revision received 17 January 2006.
Let G denote a connected semisimple and simply connected algebraic group over an algebraically closed field k of positive characteristic and let g denote a regular element of G. Let X denote any equivariant embedding of G. We prove that the closure of the conjugacy class of g within X is normal and CohenMacaulay. Moreover, when X is smooth we prove that this closure is a local complete intersection. As a consequence, the closure of the unipotent variety within X shares the same geometric properties. 2000 Mathematics Subject Classification 14M17 (primary), 13A35 (secondary).