
Mark Kisin
Universität Munster
Equivariant Poincare polynomials and counting points in
characteristic p.
Friday 11th, April 12:0512:55pm,
Stephen Roberts.
Let M_{0,n} be the moduli spaceparametrising ordered
ntuples of points on the complex sphere. I will explain joint
work with Gus Lehrer in which we compute the action of the symmetric
group S_{n} on the cohomology of
M_{0,n}. The proof exploits a connection  going back
to Andre Weil  between the topology of varieties in characteristic
p, and their arithmetic in positive characteristic.







