Aktuelle Vorträge und Veranstaltungen

Wintersemester 2021/22

Das Seminar findet bis auf weiteres über Zoom statt. Der Link wird am Morgen des Seminartermins via Zoom an die Mitglieder der Arbeitsgruppe geschickt. Falls Sie die Emails unserer Arbeitsgruppe nicht bekommen, melden Sie sich bitte mit einer kurzen Email an ulirsch[at]math.uni-frankfurt.de an.

The Seminar will be held via Zoom for the foreseeable future. The link will be sent to all members of our working group on the morning of the seminar. If you do not receive the emails of our working group, please register with a short email to ulirsch[at]math.uni-frankfurt.de.


Do, 9. Dezember 2021

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 7: A crash course on toric varieties [Felix Goebler] 
  • 16:30 - 17:30: Talk 8: Minkowski weights and the Chow ring of a toric variety [Luca Battistella] 

Mi, 12. Januar 2022

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Oishee Banerjee (University of Bonn): Filtration of cohomology via symmetric (semi)simplicial spaces
  • Abstract: Inspired by Deligne’s use of the simplicial theory of hypercoverings in defining mixed Hodge structures we replace the indexing category ∆ by the symmetric simplicial category ∆S and study (a class of) ∆S-hypercoverings, which we call spaces admitting symmetric (semi)simplicial filtration. For ∆S-hypercoverings we construct a spectral sequence, somewhat like the Cˇech-to-derived category spectral sequence. The advantage of working on ∆S is that all of the combinatorial com- plexities that come with working on ∆ are bypassed, giving simpler, unified proof of known results like the computation of (in some cases, stable) singular cohomol- ogy (with rational coefficients) and étale cohomology (with Q_l coefficients) of the moduli space of degree n maps C to a projective space , C a smooth projective curve of genus g, of unordered configuration spaces, that of the moduli space of smooth sections of a fixed gdr that is m-very ample etc.

Do, 20. Januar 2022

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 9: Bergman fans and the permutohedral variety [Stefan Rettenmayr] 
  • 16:30 - 17:30: Talk 10: Intersection theory on the permutohedral variety [Andreas Gross] 

Mi, 26. Januar 2022

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Tyler Kelly (Birmingham): An Open Enumerative Theory for Landau-Ginzburg models.
  • Abstract: Landau-Ginzburg models consist of a pair (W, G) where W is a potential (that is, a complex valued regular function from a quasi-affine variety X) and G is a group acting on X so that W is invariant. In the context of mirror symmetry, oftentimes they can be viewed as a noncommutative symplectic deformation of a symplectic manifold. Over the past couple of decades there has been work in establishing an enumerative theory for a Landau-Ginzburg model, akin to Gromov-Witten theory. Recently, a few of us have aimed to create an open enumerative theory for Landau-Ginzburg models. In the end, we can construct the mirror Landau-Ginzburg model's potential function as a generating function of open enumerative invariants. This provides the Landau-Ginzburg analogue to Maslov index two discs / tropical discs for a symplectic manifold. This is joint work with Mark Gross and Ran Tessler.

Mi, 2. Februar 2022

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Christin Bibby (Louisiane State University): tba.

Do, 03. Februar 2022

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 11: The Chow ring of a matroid [Alex Küronya] 
  • 16:30 - 17:30: Talk 12: June Huh (Princeton): Kazhdan-Lusztig theory of matroids and its relation to Hodge theory

Mi, 9. Februar 2022

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Pieter Belmans (Luxemburg): tba.

Mi, 16. Februar 2022

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Petru Constantinescu (MPIM Bonn): tba.

Do, 17. Februar 2022

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Last meeting: Discussion of topics for the next seminar


Bereits gehaltene Vorträge im WiSe 2021/22:

Mi, 06. Oktober 2021

  • Bachelorabschlussvortrag (on zoom)
    11:00 - 12:00: Tim Paulini (Univ. Frankfurt): Der Fox'sche Differentialkalkül

    Den zoom link zu dieser Veranstaltung erhalten Sie bei Interesse per email von stix[at]math.uni-frankfurt.de

Mi, 20. Oktober 2021

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Remi Reboulet (Universite Grenoble Alpes): Plurisubharmonic geodesics in non-Archimedean geometry

Do, 28. Oktober 2021

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 1: Overview [Martin Ulirsch] 
  • 16:30 - 17:30: Talk 2: Matroid basics I – cryptomorphisms and examples [Ingmar Metzler]

Mi, 10. November 2021

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: Yujie Xu (Harvard University): On normalization in the integral models of Shimura varieties of Hodge type.
  • Abstract: Shimura varieties are moduli spaces of abelian varieties with extra structures. Over the decades, various mathematicians (e.g. Rapoport, Kottwitz, etc.) have constructed integral models of Shimura varieties. In this talk, I will discuss some motivic aspects of integral models of Hodge type constructed by Kisin (resp. Kisin-Pappas). I will talk about recent work on removing the normalization step in the construction of such integral models, which gives closed embeddings of Hodge type integral models into Siegel integral models. I will also mention an application to toroidal compactifications of such integral models.

Do, 11. November 2021

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 3: Matroid basics II – exercise session [no speaker] 
  • 16:30 - 17:30: Talk 4: Matroid basics III – the lattice of flats [Arne Kuhrs]

Do, 25. November 2021

Hodge theory of matroids. GAUS-Seminar – WiSe 2021/22.

  • 15:15 - 16:15: Talk 5: Operations on matroids [Pedro Souza]
  • 16:30 - 17:30: Talk 6: The characteristic polynomial [Lucie Devey] 

Mi, 1. Dezember 2021

  • Oberseminar Algebra und Geometrie (on Zoom)
    16:00 - 17:00: David Reutter (MPI Bonn): Semisimple topological quantum field theories and exotic smooth structure.
  • A major open problem in quantum topology is the construction of an oriented 4-dimensional topological quantum field theory (TQFT) in the sense of Atiyah-Segal which is sensitive to exotic smooth structure. More generally, how much manifold topology can a TQFT see? After introducing topological quantum field theories and sketching a number of examples, I will outline an answer to this question for even-dimensional `semisimple’ TQFT.  Such theories can at most see the stable diffeomorphism type of a manifold and conversely, if two sufficiently finite manifolds are not stably diffeomorphic then they can be distinguished by semisimple field theories. In this context, `semisimplicity' is a certain algebraic condition satisfied by all currently known examples of linear algebraic TQFT in more than two dimensions, and two 2n-manifolds are said to be stably diffeomorphic if they become diffeomorphic after connected sum with sufficiently many copies of S^n x S^n. If time permits, I will discuss various implications, such as the fact that 4d oriented semisimple TFT cannot see smooth structure, while unoriented ones can. This is based on arXiv:2001.02288 and ongoing joint work with Christopher Schommer-Pries. 


Sommersemester 2021

Das Seminar findet bis auf weiteres über Zoom statt. Der Link wird am Morgen des Seminartermins via Zoom an die Mitglieder der Arbeitsgruppe geschickt. Falls Sie die Emails unserer Arbeitsgruppe nicht bekommen, melden Sie sich bitte mit einer kurzen Email an ulirsch[at]math.uni-frankfurt.de an.

The Seminar will be held via Zoom for the foreseeable future. The link will be sent to all members of our working group on the morning of the seminar. If you do not receive the emails of our working group, please register with a short email to ulirsch[at]math.uni-frankfurt.de.


* Das Seminar findet zusammen mit der Technischen Universität Darmstadt, der Ruprecht-Karls-Universität Heidelberg und der Johannes Gutenberg-Universität Mainz als DaFraHeiMai statt.


Bereits gehaltene Vorträge im SoSe 2021:

Do, 22. April 2021, Oberseminar Algebra und Geometrie (on Zoom)

DaFraHeiMai* / GAUS-Seminar: The P=W conjecture

  • 15:15-16:15 (Talk 1) Martin Möller:  "What is the P=W conjecture about?" 
    This talk is an overview over the topic serving as a guideline for the following talks.
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 2) Felix Göbler: "The Betti moduli space"
    In this talk we will be introduced to one of the several moduli spaces the conjecture is concerned with - the moduli space of (twisted) representations of the fundamental group into GL(n,C)

Do, 06. Mai 2021, Oberseminar Algebra und Geometrie (on Zoom)

DaFraHeiMai* / GAUS-Seminar: The P=W conjecture

  • 15:15-16:15 (Talk 3) Paul Kiefer:  "Hodge structures and mixed Hodge structures"  
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 4) Matti Würthen: "The mixed Hodge structure of the Betti moduli space" 

Do, 20. Mai 2021, Oberseminar Algebra und Geometrie (on Zoom)

DaFraHeiMai* / GAUS-Seminar: The P=W conjecture

  • 15:15-16:15 (Talk 5) Felix Röhrle:  "The de Rham moduli space and Riemann-Hilbert correspondence"  
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 6) Johannes Schwab: "The Dolbeault moduli space and the abelian Hodge correspondence" 

Do, 10. Juni 2021, Oberseminar Algebra und Geometrie (on Zoom)

DaFraHeiMai* / GAUS-Seminar: The P=W conjecture

  • 15:15-16:15 (Talk 7) Riccardo Zufetti:  "The Hitchin map and spectral data"  
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 8) Jakob Stix: "Non-Abelian Hodge Correspondence" 

Fr, 11. Juni 2021, Mini-Workshop on Toric Degenerations (on Zoom)

  • 14:00-15:00 Victor Batyrev (Univeristät Tübingen)
    15:00-15:15: Break
  • 15:15-16:15: Lara Bossinger (UNAM Oaxaca)
    16:15-16:30: Break
  • 16:30-17:30 Chris Manon (University of Kentucky)

Do, 24. Juni 2021

  • Oberseminar Algebra und Geometrie (on Zoom)
    DaFraHeiMai* / GAUS-Seminar: The P=W conjecture
  • 15:15-16:15 (Talk 9) Anton Güthge:  "The constructible derived category and intersection complexes"  
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 10) Can Yaylali: "Perverse sheaves and the topology of algebraic maps" 

Do, 08. Juli 2021

  • Oberseminar Algebra und Geometrie (on Zoom)
    DaFraHeiMai* / GAUS-Seminar: The P=W conjecture
  • 15:15-16:15 (Talk 11) Martin Ulirsch:  "P=W for tautological classes"  
  • 16:15-16:45: Coffee break
  • 16:45-17:45 (Talk 12) Luca Battistella: "P=W for G = GL(2, C)" 

Di, 13. Juli, Do, 15. Juli, Fr. 16. Juli 2021

  • Ruth Moufang Lectures by Jennifer Balakrishnan (Boston University): Rational points on curves: from Diophantus to the present day
  • 13. Juli, 15:00 - 15:45 Uhr Andrea Blunck (University of Hamburg): Ruth Moufang and her work on projective planes
  • 13. Juli, 16:00 - 17:00 Uhr Jennifer Balakrishnan: Questions about rational points on curves
  • 15. Juli, 16:00 - 17:00 Uhr Jennifer Balakrishnan: Mordell’s conjecture and the last ninety-nine years
  • 16. Juli, 16:00 - 17:00 Uhr Jennifer Balakrishnan: Explicit methods for rational points on curves

Link zur neuen Vortragsseite