Seminar on Arithmetic Geometry and Algebraic Groups
This seminar is focusing on various research topics in arithmetic geometry with special regard to algebraic groups, homogeneous spaces and related structures or problems.
Normally, one or two online talks are expected to be scheduled per month. The date and time of each talk will be flexibly arranged according to the speaker’s convenience.
The online talks are usually run via Zoom Meeting or sometimes Voov Meeting (or equivalently, Tencent meeting in China mainland). Please read the instructions on downloading and using Voov here.
If you want to receive annoucements of the seminar talks, please email one of the organizers.
Organizers
CAO Yang (Shandong Univ., Jinan); yang###1988@email.sdu.edu.cn ###=Yang’s family name
HU Yong (Southern Univ. Sci. Tech., Shenzhen) ; ###@sustech.edu.cn ###=first 3 letters of “huyong”
HUANG Zhizhong (Chinese Acad. Sci., Beijing) ; zhizhong.#####@yahoo.com #####=Zhizhong’s family name
LEE Ting-Yu (Taiwan Univ., Taiwan); tingyu###@ntu.edu.tw ###=Tingyu’s family name
TIAN Yisheng (Harbin Institute Tech., Harbin); tys####@mail.ustc.edu.cn ####=first 4 letters of “mathematics”
XU Fei (Capital Normal Univ., Beijing); xuf##@math.ac.cn ##=last 2 letters of “fei”
Past sessions: 2022 Session 2023 Session 2024 Session 2025 Session
The next talk on Monday, October 12, 2026, 16:30--17:30 (Beijing Time).
2026 Fall Session
Date: 04.12.2026 (dd.mm.yyyy) Time: 16:00–17:00 (Beijing Time)
or
Date: 04.12.2026 (dd.mm.yyyy) Time: 09:00–10:00 (Central European Winter Time)
Zoom Meeting ID: available upon request
Speaker: Ulrich Derenthal (Leibniz Universität Hannover)
Title: TBA
Abstract: TBA
Ref：
Date: 16.11.2026 (dd.mm.yyyy) Time: 16:30–17:30 (Beijing Time)
or
Date: 16.11.2026 (dd.mm.yyyy) Time: 09:30–10:30 (Central European Winter Time)
Zoom Meeting ID: available upon request
Speaker: Otto Overkamp (Heinrich-Heine-Universität Düsseldorf)
Title: TBA
Abstract: TBA
Ref：
Date: 02.11.2026 (dd.mm.yyyy) Time: 16:30–17:30 (Beijing Time)
or
Date: 02.11.2026 (dd.mm.yyyy) Time: 09:30–10:30 (Central European Winter Time)
Zoom Meeting ID: available upon request
Speaker: Vladimir Mitankin (Bulgarian Academy of Sciences)
Title: Semi-integral points on Markoff pairs
Abstract: In this talk, we shall discuss the status of local-global principles for semi-integral points on Campana orbifolds arising from Markoff surfaces and obstructions to them. We will then explain the distribution of Campana orbifolds which have semi-integral points that do not come from integral points on the corresponding Markoff surface. This talk is based on a joint work with Justin Uhlemann.
Ref：
Date: 16.10.2026 (dd.mm.yyyy) Time: 16:00–17:00 (Beijing Time)
or
Date: 16.10.2026 (dd.mm.yyyy) Time: 10:00–11:00 (Central European Summer Time)
Zoom Meeting ID: available upon request
Speaker: Olivier Benoist (CNRS)
Title: Étale cohomology of Stein algebras
Abstract: Artin’s comparison theorem states that the étale cohomology and the singular cohomology of a complex algebraic variety are isomorphic. I will discuss a complex-analytic counterpart of this result, in Stein geometry (Stein spaces being the complex-analytic analogues of affine algebraic varieties). I will also explain applications to the topology of Stein spaces.
Ref：
Date: 12.10.2026 (dd.mm.yyyy) Time: 16:30–17:30 (Beijing Time)
or
Date: 12.10.2026 (dd.mm.yyyy) Time: 10:30–11:30 (Central European Summer Time)
Zoom Meeting ID: available upon request
Speaker: Federico Scavia (CNRS, Université Sorbonne Paris Nord)
Title: Splitting Brauer classes by genus one curves
Abstract: Let F be a field. A basic way to study a Brauer class over F is through its splitting fields, that is, field extensions of F over which the class becomes trivial. I will discuss a question of Clark and Saltman: is every Brauer class over F split by a smooth projective genus one curve over F? Equivalently, does every Severi-Brauer variety X/F admit a morphism C -> X, with C a smooth projective curve of genus one? I will present joint work with Zinovy Reichstein showing that the answer is no in general. I will then discuss joint work with Ben Antieau and Asher Auel showing that, in contrast, the answer is yes over number fields.
Ref:
2026 Spring Session
No talk was scheduled in this spring semester.