Organizers Prof. Dr. Ulrich Thiel, M.Sc. Fabian Mäurer

This is the regular meeting of the Working Group Thiel. The seminar takes place every two weeks on Thursdays at 14:00 in room 48-436 and presentations will be announced the Monday before. Guests – as listeners or speaker – are always welcome. Here we list only the meetings with formal presentations. For notifications please subscribe to the following mailing list:

https://lists.rptu.de/wws/subscribe/math-ag-thiel-extern?previous_action=info 

Next Talk:

• 16. Juli: Tobias Metzlaff: Painting the Euclidean space: spectral bounds for set avoiding graphs

At the ITWM. Please come to the registry at 8:45.

Abstract: 

The Hadwiger–Nelson–problem (1950) was arguably the starting point for a class of problems that revolve around computing the chromatic number of set- avoiding graphs in the Euclidean space. The question is, given a “forbidden” set S ⊆ Rn, e.g., the unit sphere or the boundary of a polytope, how many colors are needed to “paint” the space Rn, so that no two points, whose difference lies in S, share the same color. The number of colors can be bounded from above and below with certain techniques from various branches of mathematics and computer science.

In this talk, I will specifically address the computation of the “spectral bound”, which gives a lower bound for the chromatic number. We will focus on forbidden sets which are the Voronoï cells of lattices with nice symmetry properties. Specific examples are the hexagon, cube, rhombic dodecahedron and icositetrachoron. The computation involves the minimization of the Fourier transformation of a measure on the forbidden set and can be achieved through techniques from polynomial optimization. The goal is to work towards the E8 and Leech lattice, which are known to be among the few lattices providing optimal sphere packings.

I will present new proof techniques for analytical results as well as improved numerical bounds, which are based on joint work with Evelyne Hubert (Sophia Antipolis), Philippe Moustrou (Toulouse) and Cordian Riener (Tromsø).

• 18. Juli: Chiara Fend: Persistent Homology for Stochastic Geometry and Spatial Statistics

• 04. Juli: Fabian Mäurer: On Fusion Categories, Their Centers and Module Categories

• 11. April: Cailan Li (Columbia University) The Two-Color Ext Soergel Calculus

• 29. February: Marion Boucrot (Université Grenoble Alpes): The relation between A-infinity morphisms and pre-Calabi-Yau morphisms

• 25. January: Jonathan Gruber (University of York): Centers and centralizers in (double) affine Hecke algebras

• 18. January: Sebastian Debus (TU Chemnitz): Specht Ideals

• 07. December:  T. Metzlaff: Chromatic numbers of set avoiding graphs

• 09. November 2023: L. Rogel: Khovanov Homologie

• 07. September 2023: T. Metzlaff: Real Quadratic Fields

• 20. Juli 2023: U. Thiel: Split and non-split Representations

• 22. Juni 2023: Johannes Schmitt: Basiswissen: Gröbner, SAGBI, Khovanskii 

• 25. May 2023: T. Metzlaff: Symmetry in Trigonometric Optimization

• 13. April 2023: T. Metzlaff: Polynomielle Optimierung

• 16. March 2023: U. Thiel: Hecke Algebras

• 16. February 2023: F. Mäurer: Von Planaren Algebren und dem Haagerup Subfactor

• 26. January 2023: T. Metzlaff: Diagonale Invariantentheorie

• 12. January 2023: T.Metzlaff: Multiplikative Invariantentheorie

• 08. December 2022: F. Mäurer: ZFC, ETCS und Typentheorie

• 24. November 2022: J. Schmitt: Kaplanskys Vermutungen sind NP-schwer

• 10.November 2022: E. Thorn: Comodules, Coalgebras and Reconstruction

• 13.October 2022: L. Rogel: Monoide und ihre Darstellungen

• 15. September 2022: F. Mäurer: Lean 4

• 7. July 2022: D. Mathiä: Kristallbasen und zelluläre Charaktere

• 23. June 2022: E. Thorn: Perfecting Group Schemes

• 9. June 2022: M. Hauck: Der Satz von Kronecker–Weber und explizite Klassenkörpertheorie

• 19. May 2022: F. Mäurer: Tensorkategorien in Julia II

• 12. May 2022: F. Mäurer: Tensorkategorien in Julia

• 28. April 2022: E. Thorn: Einführung in Ext-Gruppen

• 17. March 2022: J. Schmitt: Köchervarietäten

• 17. February 2022: M. Albert: Implementierung von Iwahori-Hecke Algebren in Julia

• 3. February 2022: M. Walch: Grothendiecks Homotopie-Hypothese

• 20. January 2022: M. Neumann-Brosig: Ein Algorithmus zur Bestimmung der Frattini Untergruppe polyzyklischer Gruppen

• 2. December 2021: Q. L. Duc: The algebra of distributions on an affine group scheme

• 18. November 2021: L. Rogel: Die Temperley-Lieb-Kategorie und ihre Geheimnisse

• 4. November 2021: D. Mathiä: Nikolauskonferenz 2021 Probevortrag

• 21. October 2021: E. Thorn: Was ist eine zelluläre Algebra

• 7. October 2021: D. Mathiä: Erzeugende Funktionen

• 23. September 2021: F. Mäurer: Modulare Tensorkategorien

• 12. August 2021: J. Schmitt: Invariantentheorie

• 15. July 2021: L. Rogel: Der J-Ring und seine Kategorifizierung

• 1. July 2021: T. Schmit: Computations in Coxeter Groups

• 17. June 2021: M. Walch: Autoencoders, Time Series, and Visualizations

• 6. May 2021: U. Thiel: Zelluläre Algebren

• 22. April 2021: D. Mathiä: Mastermind

• 8. April 2021: U. Thiel: Schneℓℓkurs in ℓ-adischer Kohomologie

• 1. April 2021: Q. L. Duc: Introduction to Group Schemes

• 25. March 2021: J. Schmitt: Cox Ringe

• 11. March 2021: E. Thorn: Einführung in die Komplexitätstheorie

• 25. February 2021: D. Mathiä: Das plaktische Monoid

• 11. February 2021: C. Brendel und J. Scheinert: Implementierung einer Chess-Engine

• 17. December 2020: L. Rogel: Die Zentrumskategorie

• 26. November 2020: J. Schmitt: McKay-Korrespondenzen

• 12. November 2020: E. Thorn: Einführung in Soergel Bimoduln

• 29. October 2020: M. Walch: Mord und Totschlag

• 22. October 2020: D. Mathiä: Archetypen und das kollektive Unbewusste

• 29. September 2020: U. Thiel: Triangulierte Kategorien

• 8. September 2020: J. Schmitt: Quotientenvarietäten

• 24. August 2020: L. Rogel: Die Kategorie G-äquivarianter Garben auf einer endlichen Menge

• 11. August 2020: D. Mathiä: Schur-Weyl-Dualität

• 29. July 2020: M. Walch: (Deep) Persistent Homology

• 7. July 2020: L. Rogel: Was ist eine Fusionskategorie

• 23. June 2020: J. Schmitt: Die Divisorenklassengruppe

• 9. June 2020: D. Mathiä: Einführung in Matroide