3 papers
math.AG2025
Torsors over the Rational Double Points in Characteristic
Christian Liedtke, Gebhard Martin, Yuya Matsumoto
We study torsors under finite group schemes over the punctured spectrum of a singularity in positive characteristic. We show that the Dieudonné module of the (loc,loc)-pa…
math.AG2025
Linearly Reductive Quotient Singularities
Christian Liedtke, Gebhard Martin, Yuya Matsumoto
We study isolated quotient singularities by finite and linearly reductive group schemes (lrq singularities for short) and show that they satisfy many, but not all, of the known pro…
math.AG2024
Bounding geometrically integral del Pezzo surfaces
Fabio Bernasconi, Gebhard Martin
We prove several boundedness statements for geometrically integral normal del Pezzo surfaces over arbitrary fields. We give an explicit sharp bound on the irregularity if i…