The seminar takes place every Thursday from 1pm to 2pm in room B217 of the science building.
17.9.2026
DongSeon Hwang (IBS Center for Complex Geometry, Daejeon, South Korea)
Cascades of klt del Pezzo surfaces of Picard number one
There have been numerous attempts to classify log del Pezzo surfaces. In this talk, I will quickly summarize these developments and present my work on the classification of klt del Pezzo surfaces of Picard number one. The result is obtained by generalizing the notion of ‘cascades’ of nonsingular del Pezzo surfaces, following the approach initiated by Miyanishi and Zhang.
24.9.2026
Allen Knutson (Cornell University, Ithaca, New York, USA)
The mathematics of juggling, old and new
I’ll explain how to associate a juggling pattern to a matrix (and in the process,
give a mathematical definition of juggling pattern, familiar to jugglers since
the mid-’80s). This defines the “positroid” stratification of the space of k x n matrices,
with many great geometric features (e.g. the strata are smooth and their
closures are normal). Much of this has been understood since 2013 down
on the Grassmannian (matrices up to row operations) but there are new
features when working upstairs on matrices. The 2013 work is joint with
Thomas Lam and David Speyer, the new with Paul Zinn-Justin.
1.10.2026
Anastasia Vikulova (Universität Basel, Switzerland)
Composition of Sarkisov links between del Pezzo surfaces
In this talk we show that for any two birationally equivalent minimal del Pezzo surfaces there is a birational map between them which is a composition of at most two Sarkisov links.
15.10.2026
Masafumi Hattori(University of Kyoto, Japan)
K-moduli wall crossing for quasimaps and automorphic forms for moduli of rational elliptic surfaces
The moduli space of rational elliptic surfaces has two natural compactifications
arising from very different constructions. One is described by the GIT
Moduli of rational elliptic surfaces, while the other comes from the Baily–Borel
compactification of an eight-dimensional ball quotient.
The relation between these two compactifications has been studied from several
different viewpoints, including stable maps, KSBA moduli, and automorphic forms.
In this talk, I will explain how to interpolate them by a family of
moduli spaces. We develop a theory of K-moduli wall crossing for quasimaps to construct them.
Furthermore, we identify the resulting models on the ball quotient side using automorphic forms.
This is a joint work with Yota Maeda.
22.10.2026
Christopher Heng Chiu (University of Bern, Switzerland)
The geometry of jet and arc spaces
In this talk we will start with a gentle introduction to jet and arc spaces and their connection to the birational geometry of algebraic varieties. One incarnation of this connection goes roughly as follows: to each exceptional divisor E on a resolution of X one associates a subset of the arc space of X, whose codimension computes the discrepancy with respect to E. More recent results show that this codimension coincides with the embedding dimension at certain points of the arc space. We will connect this to work describing the formal-local structure of the arc space, such as a generalization of the Drinfeld-Grinberg-Kazhdan theorem.
9.11.2026 (MONDAY)
Francesco Gallinaro (Scuola Normale Superiore, Pisa, Italy)
On the elementary theory of the real exponential field
In 1951, Tarski asked whether the theory of the real exponential field is decidable: whether there is an algorithm that, given a first-order formula in the language of exponential rings (for example, the formula asserting that a certain system of exponential polynomials is solvable), determines whether that formula holds in the reals. In this talk I will give an introduction to this problem and to the partial results that have been obtained towards its solution. I will focus on recent joint work with Alessandro Berarducci in which we prove that, assuming Schanuel’s conjecture from transcendence theory, the theory of the real exponential field has a very simple axiomatization.
12-13.11.2026
BENDZ Seminar of algebraic geometry in Basel
19.11.2026
tba
tba
tba
26.11.2026
Hamid Abban (University of Neuchâtel, Switzerland)
tba
tba
3.12.2026
tba
tba
tba
10.12.2026
Valentin Huguin(Université de Picardie Jules Verne, Amiens)
tba
tba
17.12.2026
tba
tba
tba
25.2.2027
Sébastien Boucksom (Paris, Jussieu)
tba
tba
