Oberseminar Sommersemester 2026
Die Vorträge finden jeweils donnerstags um 16:45 Uhr im Raum WSC-N-U-3.05 (im Mathematikgebäude ) statt.
Der Tee findet ab 16:15 in Raum O-3.46 statt.
Alle Interessenten sind herzlich eingeladen!
The seminar takes place on Thursday, starting at 4:45pm. The duration of each talk is about 60 minutes. Before the talk, at 4:15pm, there is tea in room O-3.46.
Everybody who’s interested is welcome to join.
Directions from the train station.
| 16.04.2026 | Marta Pieropan (Utrecht) | Campana points and firmaments |
| 23.04.2026 | (reserved) | t.b.a. |
| 30.04.2026 | Jelena Ivancic (MPI Bonn) | Infinitesimal characters for the completed cohomology for $\mathrm{GL}_n$ over CM fields |
| 07.05.2026 | Luca Francone (Rome) | From reductive groups to quantum groups |
| 21.05.2026 | Frank Gounelas (Bonn) | t.b.a. |
| 28.05.2026 | Nicolas Dupre (Wuppertal) | t.b.a. |
| 11.06.2026 | Ben Moonen (Nijmegen) | t.b.a. |
| 18.06.2026 | N.N. | t.b.a. |
| 25.06.2026 | Baptiste Calmès (Lens) | t.b.a. |
| 02.07.2026 | Joshua Jackson (Cambridge) | t.b.a. |
| 09.07.2026 | Aryaman Patel (Saarbrücken) | The Hitchin morphism over higher-dimensional base manifolds |
| 16.07.2026 | Gabriele Bogo (Bielefeld) | t.b.a. |
| 23.07.2026 | N.N. | t.b.a. |
Abstracts
Marta Pieropan: Campana points and firmaments
Determining the image of the set of rational points under a morphism of varieties is a very natural and difficult question. The case where the morphism is geometrically surjective has been studied extensively. From Campana’s theory of orbifolds, it follows that over a number field, the image of the set of rational points is contained in the set of Campana points for the orbifold base of the morphism. This first approximation of the image of the set of rational points is refined by Abramovich’s theory of firmaments. This talk presents some arithmetic questions about Campana points, and a proof of a claim by Abramovich about lifting firm points under toroidal morphisms in joint work with Herr, Mehidi and Poiret.
Jelena Ivancic: Infinitesimal characters for the completed cohomology for $\mathrm{GL}_n$ over CM fields
I will talk about joint work with Vaughan McDonald where we prove a conjecture of Dospinescu-Paskunas-Schraen for the case of $\mathrm{GL}_n$ over CM fields (under some assumptions). This conjecture is a part of the expected local-global compatibility at p in Langlands program: it says that the infinitesimal action on a Hecke eigenspace appearing in the locally analytic vectors of completed cohomology is given by a character which ‘‘encodes’‘ the Hodge-Tate weights of the associated Galois representation.
I will discuss this statement and our proof for $\mathrm{GL}_n$ over CM field.
Luca Francone: From reductive groups to quantum groups
In this talk, we introduce the discrete gauge action: a generalization of the conjugation action of a complex reductive algebraic group, together with a family of geometric objects called schemes of bands. We explain how these constructions provide a geometric interpretation of some fundamental objects in the representation theory of quantum affine algebras and prove a conjecture of Frenkel and Reshetikhin of 1998. This is joint work with Bernard Leclerc.