Purity reconsidered

Abstract

Talk in the conference: The Cohomology of Moduli Spaces Organized by Gerard van der Geer and Carel Faber Amsterdam, 16-20 XII 2002

Convention: all base schemes will be in characteristic p. Writing k or Ω we will assume k=k
Fp
respectively Ω=Ω
Fp We will write X ->S for a p divisible group over a base S(and sometimes will say a family of p divisible groups), while we tend to write X when we consider a p divisible group over a base field (but we are not strict in this convention) Instead of p divisible group one can also use the equivalent notion Barsotti Tate group