November 2024
Location: Lipschitz-Saal, Endenicher Allee 60
Abstract: A prominent tool in the classification of knots and links are homological invariants known as link homology theories. A particularly prominent homology theory, known as Khovanov-Rozansky homology has garnered significant attention due to its conjectured connections to various geometric objects, such as the Hilbert scheme of points on the plane and affine Springer fibers. Although these conjectures are expected to hold for all algebraic links, for the most part they have only been verified for torus links. A fundamental step in computing the Khovanov-Rozansky homology of algebraic knots and thus verifying these conjectures is understanding how current tools can be expanded to include cabled torus knots. In this talk I will explain how combinatorially computing the Khovanov-Rozansky homology of the larger family of Coxeter knots gave way to one of the first computations of this homology theory for a nontrivial family of cabled torus knots. A consequence of obtaining closed combinatorial formulas, is a proof of a conjecture of Oblomkov-Rasmussen-Shende for the (d,dnm+1) cable of the (n,m) torus knot that relates its Khovanov Rozansky homology to the compactified Jacobian of the associated plane curve singularity.
Location: Lipschitz-Saal, Endenicher Allee 60
Location: MPIM Seminar Room
Location:
Room: Zoom meeting 641 6780 5250
https://uni-bonn.zoom-x.de/j/64167805250, password is the seminar name
(3 letters, lowercase)
Abstract:
For d≥4 and p a sufficiently large prime, we construct a lattice Γ≤PSp2d(ℚp), such that its universal central extension cannot be sofic if Γ satisfies some weak form of stability in permutations. In the proof, we make use of high-dimensional expansion phenomena and, extending results of Lubotzky, we construct new examples of cosystolic expanders over arbitrary finite abelian groups. This is joint with with Lukas Gohla.
Location: MPIM Lecture Hall
Location: MPIM Lecture Hall
Abstract: I will talk about a complete proof of Mukai's Theorem describing K3 surfaces and prime Fano threefolds of genus g \in {7,8,9,10,12} as zero loci of global sections of equivariant vector bundles on Grassmannians, where the key role is played by Schubert divisors. This is a joint result with Arend Bayer and Emanuele Macri.
Location: Lipschitzsaal, Endenicher Allee 60
Abstract: Here is a motivating question, which is a special case of a more general problem: The moduli space of K3 surfaces in characteristic p is stratified by the height of the formal Brauer group, and the smallest stratum (the supersingular locus) is further stratified by the Artin invariant. If we give ourselves an explicit K3 surface, e.g. a quartic surface in P^3, how can we calculate in which stratum it lies? In my talk, I will explain what an F-zip is (I will not assume you already know this), and how this relates to the above problem. Under mild technical assumptions, we can associate an F-zip to every smooth projective variety in characteristic p, and such F-zips have been classified. I will explain some new techniques that allow us to calculate the F-zips of some accessible types of varieties, such as projective hypersurfaces.
Location: Lipschitzsaal, Endenicher Allee 60
Location: MPIM Seminar Room
Location: Raum 1.008 in MI
Abstract: An affine Lie algebra g is a central extension of the loop algebra of a complex simple Lie algebra, and a g-module is said to have (relative) level k if the canonical central element acts by the scalar k-h, where h is the dual Coxeter number. For all levels k that are not positive rational or zero, Kazhdan and Lusztig have defined a braided monoidal structure on a parabolic BGG category O of g-modules of level k. In this talk, I will explain the definition of a braided monoidal structure on the category O at positive rational levels, via a monoidal enhancement of Brundan and Stroppel's semi-inifnite Ringel duality.
This is based on joint work with Johannes Flake and Robert McRae.
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: MPIM Seminar Room
Location: MPIM Lecture Hall
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Location: MPIM Lecture Hall
Abstract: In this talk I will present two theorems concerning definable subsets of the structure $\mathbb{T}_{\log}$: the differential field of logarithmic transseries. One result is that the zero sets of arbitrary nonzero differential polynomials are co-analyzable relative to the constant field $\mathbb{R}$. The other (joint work with Elliot Kaplan and Nigel Pynn-Coates) is a characterization of the "small" definable subsets of the asymptotic couple. In particular, the characterization implies the asymptotic couple is d-minimal, i.e., every definable subset in 1-variable either has interior or is a finite union of discrete sets.
Location: SemR N0.003, Endenicher Allee 60
Location: MPIM Seminar Room
Location: University of Bonn, N0.003 (Neubau)
Location: MPIM Lecture Hall
Abstract: The cohomological dimension cd(G) of a group G is the maximal number n such that nth cohomology group H^n(G,M) of G is nontrivial for some ZG-module M. By Eilenberg-Ganea and Stallings-Swan theorems, cd(G) always equals the geometric dimension gd(G) := min{dim BG} of G with one potential exception when cd(G) = 2. In this talk, we will discuss the possibility of extending the Eilenberg-Ganea theorem to group homomorphisms.
Location: Room 0.003, Endenicher Allee 60
Location: Endenicher Allee 60, Hausdorffraum and Plückerraum
We would like to encourage you to join the challenge of promoting diversity, equity, and inclusion within the Bonn mathematics community in all its aspects. To this end the equal opportunity working group is inviting you to a networking event on November 20.11.2024 from 13:00 to 14:45 in the Plücker room and Hausdorff room. We would like to bring together people interested in specific topics such as underrepresented groups in mathematics, global justice, family support, accessibility, neurodivergence, mental health, etc . The aim of this get together is to identify potential initiatives and to form teams interested in pursuing them. The equal opportunity working group offers to support and coordinate new initiatives. The event will start with a short presentation of existing current efforts followed by informal exchanges in small groups over coffee, tea, and cake.
Location: MPIM Lecture Hall
Location: Endenicher Allee 60, Lipschitz hall
Location: Max Planck Institute - Lecture Hall
Abstract:
Let X be a very general hypersurface of dimension 3 and degree d at least 6. Griffiths and Harris conjectured in 1985 that the degree of every curve on X is divisible by d. Substantial progress on this conjecture was made by Kollár in 1991 via degeneration arguments. However, the conjecture of Griffiths and Harris remained open in any degree d. In this talk, I will explain how to prove this conjecture (and its higher-dimensional analogues) for infinitely many degrees d.
Location: MPIM Seminar Room
Location: MPIM Lecture Hall
Location: MPIM Lecture Hall
Location: MPIM Lecture Hall
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Location: Max Planck Insitut - Hörsaal
Abstract: we prove the Kuznetsov components of a series of hypersurface in projective space reconstruct the hypersurfaces. Our method allow us to work for hypersurfaces in weighted projective space, and obtain the reconstruction theorem of veronese double cone, which is a long-time open case. I will show how to construct the infinitesimal variation of Hodge structure from certain Kuznetsov components. Using classical generic Torelli theorem, this implies the Kuznetsov components reconstruct the algebraic variety generically. Joint with J. Rennemo and S.Z. Zhang.
Location: Endenicher Allee 60, Lipschitzssaal
Do you identify with a specific gender? Why though? On November 29, Solveïg (none or hen/hens pronouns) will give us an insight into non-binary perspectives on gender and sex in about 45 minutes. No prior knowledge is required, Solveïg will speak in German and summarize key points in English. Afterwards there will be the opportunity to discuss the topic in smaller groups and spend time with other interested people over tea and cookies. We start at 15 c.t. with the talk in the Lipschitzsaal. If you can‘t make it to the talk, don‘t worry about it and join us at 4 pm for discussion, tea and cookies.
See you then!
Your LGBTQ+ Department
December 2024
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitz Lecture Hall
Abstract: We present a general shape optimization framework based on the method of mappings in the Lipschitz topology. We propose and numerically analyse steepest descent and Newton-like minimisation algorithms for the numerical solution of the respective shape optimization problems. Our work is built upon previous work of the authors in (Deckelnick, Herbert, and Hinze, ESAIM: COCV 28 (2022)), where a Lipschitz framework for star-shaped domains is proposed. To illustrate our approach we present a selection of PDE constrained shape optimization problems and compare our findings to results from so far classical Hilbert space methods and recent p-approximations. This is joint work with Klaus Deckelnick from Magdeburg and Philip Herbert from Sussex.
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Abstract: A moldable job is a job that can be executed on an arbitrary number of processors, and its processing time depends on the number of processors allotted to it. A moldable job is monotone if its work doesn't decrease for an increasing number of allotted processors. This talk addresses the problem of scheduling monotone moldable jobs to minimize the makespan. For certain compact input encodings, a polynomial algorithm has a running time polynomial in n and log m, where n is the number of jobs and m is the number of machines. We explore how monotony can counteract the complexity arising from compact encodings and present tight bounds on the approximability of the problem with compact encoding: it is NP-hard to solve optimally, but admits a PTAS. The main focus is on efficient approximation algorithms, including a (3/2+ϵ)-approximate algorithm with a running time polynomial in log m and 1/ϵ, and linear in the number n of jobs. This is joint work with Kilian Grage, Felix Land, and Felix Ohnesorge.
Location: Seminarraum, 1st floor, Forschungsinstitut für Diskrete Mathematik/Arithmeum, Lennéstraße 2, 53113 Bonn
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
January 2025
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitzsaal
The annual symposium following the final meeting of the 2025 Abel Prize Committee will his year take place in Bonn.
Location: Lipschitzsaal
Location: Endenicher Allee 60, Lipschitz hall
February 2025
Location: Endenicher Allee 60, Lipschitz hall
March 2025
June 2025
Location: Lipschitz-Saal, Endenicher Allee 60, Bonn
Location: Endenicher Allee 60, Lipschitz hall