Oberseminar Algebra und Geometrie

Calla Tschanz (University of Bath)

Abstract:
Let X –> C be a projective family of surfaces over a curve with smooth generic fibre and simple normal crossing singularity in the special fibre X_0. We construct a good compactification of the moduli space of relative length n zero-dimensional subschemes on X\X_0 over C\{0}. In order to produce this compactification we study expansions of the special fibre X_0 together with a GIT stability condition, generalising the work of Gulbrandsen-Halle-Hulek who use GIT to offer an alternative approach to the work of Li-Wu for Hilbert schemes of points on simple degenerations. We construct stacks which we prove to be equivalent to the underlying stack of some choices of logarithmic Hilbert schemes produced by Maulik-Ranganathan.