Algebra Seminar - V. Karemaker University of Utrecht

Title: Mass formulae for supersingular abelian threefolds.

Abstract:

Using the theory of polarised flag type quotients, we determine mass formulae for all principally polarised supersingular abelian threefolds defined over an algebraically closed field k of characteristic p. We combine these results with computations of the automorphism groups to study Oort's conjecture; we prove that every generic principally polarised supersingular abelian threefold over k of characteristic >2 has automorphism group Z/2Z.

This is joint work with F. Yobuko and C.-F. Yu.