Workshop on birational geometry
April 22, 2021
Abstracts of the talks


Hiromu Tanaka

On Mori fibre spaces in positive characteristic.
The minimal model program conjecture predicts that any algebraic variety is birational to either a minimal model or a Mori fibre space. In this talk, we first summarise some results on Mori fibre spaces in characteristic zero. We then discuss which properties should extend to positive characteristic.

Gebhard Martin

Automorphism schemes of projective surfaces.
Given a proper variety X over a field k, its automorphism functor AutX is representable by a group scheme locally of finite type over k. While the abstract automorphism group AutX(k) has always been an object of interest in classical algebraic geometry, the automorphism scheme AutX itself is usually not well-studied in positive characteristic, where it contains more information than AutX(k). However, the scheme structure of AutX is of fundamental importance in the moduli and deformation theory of X. In this talk, I will describe techniques that can be used to determine AutX, give an overview of what is known about AutX if X is a (smooth) projective surface, and report on recent results on automorphism schemes of projective surfaces of special type, such as del Pezzo surfaces, elliptic surfaces, and surfaces of Kodaira dimension 0.

Jakub Witaszek

Global ±-regularity and the Minimal Model Program for arithmetic threefolds.
In this talk, I will explain a mixed characteristic analogue of Frobenius regularity and how it can be used to establish the Minimal Model Program for threefolds in mixed characteristic. This is based on a joint work with Bhargav Bhatt, Linquan Ma, Zsolt Patakfalvi, Karl Schwede, Kevin Tucker, and Joe Waldron.

Sergey Rybakov

Algebraic varieties over function fields and good towers of curves over finite fields.
Given a smooth algebraic variety over a function field we can construct a tower of algebraic curves (or, equivalently, a tower of function fields). We say that the tower is good if the limit of the number of points on a curve divided by genus is positive. For example, the generic fiber of the Legendre family of elliptic curves gives a good (and optimal) tower over Fp2. I will speak on good towers coming from K3 surfaces.



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