Stephane Bijakowski will speak on

Partial Hasse invariants and partial degrees

Abstract: The Hasse invariant of a p-divisible group detects if it is ordinary. When one considers a p-divisible group with an action of a certain ring (possibly ramified), then one can refine this invariant, and define partial Hasse invariants. Considering a finite flat subgroup, one can define its degree, and this invariant can also be refined if the subgroup is endowed with some action.

After introducing the partial degrees and partial Hasse invariants, I will show how to compute the partial degrees of the canonical subgroup.