The talk is dedicated to finite flat commutative p-group schemes over a mixed characteristic complete discrete valuation ring. The relation of group schemes of this sort to the reduction of abelian varieties will also be recalled and applied to deduce certain p-adic criteria. The most difficult result is that the generic fibre functor is "almost full" on the category of group schemes of the aforementioned type; it generalizes the fullness theorem of M. Raynaud and improves a theorem of J. Tate. The main tool is a classification result for local schemes of this sort (as given by F. Oort and the speaker); it also gives certain properties of tangent spaces of these schemes.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/3444
[3] http://www.mpim-bonn.mpg.de/node/246