April 2024
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: MPIM Lecture Hall
Abstract:
Given a family of smooth projective varieties, one can consider the relative de Rham moduli space, of flat vector bundles of rank n on the fibers. The flat vector bundles which underlie a Z-polarized variation of Hodge structure form the “non-abelian Hodge locus”. Simpson proved that this locus is closed and analytic, and he conjectured it is algebraic. Simpson's conjecture would imply a conjecture of Deligne that only finitely many representations of the fundamental group underlie a Z-PVHS on some fiber. I will discuss a proof of Deligne’s and Simpson’s conjectures, under the additional hypothesis that the Z-Zariski closure of monodromy is a cocompact arithmetic group. This is joint work with Salim Tayou.
Location: MPIM Lecture Hall
Location: Endenicher Allee 60, Lipschitz hall
Location: MPIM Lecture Hall
Location: Endenicher Allee 60, Hausdorff room
Abstract:
We invite all female* mathematicians to the next Tea Time with the title “Meet your Profs”. You will get the opportunity to network with fellow students and some of Bonn’s maths professors namely Prof. Vargas Koch, Prof. Sauermann, Prof. Rüland and Prof. Verfürth. The event will take place on April 26th from 2:30 to 5 pm in the Hausdorff-room. There will be tea and cookies for you to enjoy. Feel free to drop by whenever you want!
*All female, intersexual, non-binary and agender persons are invited.
Location: MPIM Lecture Hall
Location: MPIM Lecture Hall
Location: "Alte Sternwarte" (Poppelsdorfer Allee 47), room "Lyra"
Abstract: The talks on this MaLiS Club event will be as follows:
- Peter Krawitz (Institute for Genomic Statistics and Bioinformatics, UKB): GestaltMatcher: Delineating gene-gene interactions from dysmorphic faces
- Rosa Kreider (IRU Mathematics & Life Sciences, Bonn): Modeling Interferon-driven Immune Cell Priming in Viral Infections
- Daniel Koch (MPI for Neurobiology of Behavior – caesar): Ghost structures in biological systems
May 2024
Location: MPIM Lecture Hall
Location: Endenicher Allee 60, Lipschitz hall
Location: Room 1.008 (MI)
Abstract: A pair in involution of a finite-dimensional Hopf algebra is agroup-like element of its Drinfeld double whose adjoint action
implements its square of the antipode. This leads to a cyclic action on certain Hom-spaces. Applications can be found, for example, in the area of topological quantum field theories. Pairsin involution may not always exist, and if they do, they may not be unique. This prompts the question of how they can be detected. An important result in that direction is: Pairs in involution are in bijection with certain one-dimensional representations which in turn determine all isomorphisms of algebras between the Drinfeld mand the anti-Drinfeld double.
In this talk, we are going to study pairs in involution for general monoidal categories. As an analogue of the previous statement, we show that these pairs can be identified with "invertible" objects in a twisted centre category and that they correspond to equivalences of certain module categories. In the Hopf algebraic case, pairs in involution govern the pivotal structures of the Yetter–Drinfeld modules. This is no longer true for general monoidal categories. We provide an explicit counterexample derived from the category of ribbon tangles.
At the end of the talk, we will outline how our categorical formulation matches the Hopf algebraic one by using the formalism of Tannaka–Krein reconstruction.
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: Room 1.008 (MI)
Abstract: The goal of this talk is to give an account of a new class of non-semisimple topological field theories in three dimensions defined using the representation theory of unrolled quantum Lie superalgebras. The classical Lie superalgebras of interest, originally constructed by Gaiotto and Witten, are defined by a symplectic representation of a torus. The resulting topological field theories model homological truncations of various supergroup Chern-Simons theories and equivariant Rozansky--Witten theories. Based on work with Niklas Garner and Nathan Geer.
Location: MPI lecture hall
Abstract:
In probability theory, universality is the phenomenon where random processes converge to a common limit despite microscopic differences. For instance, the random walk, under mild conditions, converges to the same Brownian motion seen from afar, regardless of the law of each independent step. This phenomenon underlies the appearance of the random simple curve, called SLE, as the universal scaling limit of interfaces in conformally invariant 2D systems. On the other hand, a subfamily of relatively regular simple curves forms the Weil-Petersson Teichmuller space and has an essentially unique Kahler geometry. To describe these geometric structures we invoke the group structure and Kahler structure which is described via infinitesimal variations of the curves. Although these two worlds look very different we will explain how they are tied together via the Loewner energy.
The first lecture on March 6 will give an introductory overview of the link.
The second lecture on March 8 will focus on the applications and further development in exploring this link, in particular, the holography of the Loewner energy as a renormalized volume in hyperbolic 3-space. Attending the first lecture will be helpful, but not necessary, and the second lecture will be self-contained.
Location: Endenicher Allee 60, Lipschitz Lecture Hall
Abstract:
A longstanding goal of biology is to identify the key genes and species that critically impact evolution, ecology, and health. Network analysis has revealed keystone species that regulate ecosystems and master regulators that regulate cellular genetic networks. Yet these studies have focused on pairwise biological interactions, which can be affected by the context of genetic background and other species present generating higher-order interactions. The important regulators of higher-order interactions are unstudied. To address this, we apply methods from polyhedral geometry to quantify epistasis in a fitness landscape to ask how individual genes and species influence the interactions in the rest of the biological network. Joint work with Holger Eble, Lisa Lamberti, and William B. Ludington.
Location: Endenicher Allee 60, Lipschitzsaal
Abstract:
In probability theory, universality is the phenomenon where random processes converge to a common limit despite microscopic differences. For instance, the random walk, under mild conditions, converges to the same Brownian motion seen from afar, regardless of the law of each independent step. This phenomenon underlies the appearance of the random simple curve, called SLE, as the universal scaling limit of interfaces in conformally invariant 2D systems. On the other hand, a subfamily of relatively regular simple curves forms the Weil-Petersson Teichmuller space and has an essentially unique Kahler geometry. To describe these geometric structures we invoke the group structure and Kahler structure which is described via infinitesimal variations of the curves. Although these two worlds look very different we will explain how they are tied together via the Loewner energy.
The first lecture on March 6 will give an introductory overview of the link.
The second lecture on March 8 will focus on the applications and further development in exploring this link, in particular, the holography of the Loewner energy as a renormalized volume in hyperbolic 3-space. Attending the first lecture will be helpful, but not necessary, and the second lecture will be self-contained.
Location: Seminarraum, 1st floor
Abstract: We study the d-dimensional Vector Bin Packing (dVBP) problem, a generalization of Bin Packing with central applications in resource allocation and scheduling. In dVBP, we are given a set of items, each of which is characterized by a d-dimensional volume vector; the objective is to partition the items into a minimum number of subsets (bins), such that the total volume of items in each subset is at most 1 in each dimension. Our main result is an asymptotic approximation algorithm for dVBP that yields a ratio of (1 + ln d − χ(d) + ε) for all d ∈ N and any ε > 0; here, χ(d) is some strictly positive function. This improves upon the best knownasymptotic ratio of (1 + ln d + ε) due to Bansal, Caprara and Sviridenko (SICOMP 2010) for
any d > 3. By slightly modifying our algorithm to include an initial matching phase andapplying a tighter analysis, we obtain an asymptotic approximation ratio of (4/3 + ε) for the
special case of d = 2, thus substantially improving the previous best ratio of (3/2 + ε) due to Bansal, Eliáš and Khan (SODA 2016). Our algorithm iteratively solves a configuration LP relaxation for the residual instance (from previous iterations) and samples a small number of configurations based on the solution for the configuration LP. While iterative rounding was
already used by Karmarkar and Karp (FOCS 1982) to establish their celebrated result for classic (one-dimensional) Bin Packing, iterative randomized rounding is used here for the first
time in the context of Vector Bin Packing. Our results show that iterative randomized rounding is a powerful tool for approximating dVBP, leading to simple algorithms with improved approximation guarantees.
Location: MPIM Lecture Hall
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitz hall
June 2024
Invited Speakers:
- Mirela Ben-Chen (Technion Israel Institute of Technology)
- Sergio Conti (University of Bonn)
- Patrick Dondl (Albert-Ludwigs-Universität Freiburg)
- Martin Metscher (MTU Aero Engines AG)
- Felix Otto (Max-Planck-Institut für Naturwissenschaften)
- Tobias Preußer (Fraunhofer Institute for Digital Medicine MEVIS)
- Carola-Bibiane Schönlieb (University of Cambridge)
- Peter Schröder (California Institute of Technology)
- Rüdiger Schultz (Universität Duisburg-Essen)
- Gabriele Steidl (Technische Universität Berlin)
- Robert Strzodka (Universität Heidelberg)
- Max Wardetzky (Universität Göttingen)
- Barbara Zwicknagl (Humboldt-Universität zu Berlin)
Location: Lipschitz hall, Endenicher Allee 60, 53115 Bonn
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, Lipschitz hall
Abstract:
Fortschritte in der Mathematik beginnen nicht selten damit, dass man etwas Alltägliches, an dem man sonst achtlos vorübergeht, einmal genauer untersucht. Auch hinter einfachen, elementaren Fragen versteckt sich nicht selten schöne und zuweilen anspruchsvolle Mathematik. Davon ausgehend begeben wir uns auf einen Streifzug durch einige kurzweilige Themen der Mathematik.
Location: Endenicher Allee 60, Lipschitz hall
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: Endenicher Allee 60, Lipschitz hall
July 2024
Invited Speakers:
- Jon Brundan (University of Oregon)
- Shun-Jen Cheng (Academia Sinica)
- Kevin Coulembier (University of Sydney)
- Maria Gorelik (Weizmann Institute)
- Victor Kac (MIT)
- Jonathan Kujawa (University of Oklahoma)
- Andrew Manion (NC State University)
- Jonas Nehme (University of Bonn)
- Shifra Reif (Bar-Ilan University)
- Lev Rozansky (University of Chapel-Hill)
- Siddharta Sahi (Rutgers University)
- Hadi Salmasian (University of Ottawa)
- Vera Serganova (University of California, Berkeley)
- Alexander Sherman (University of Sydney)
Location: Lipschitz hall, Endenicher Allee 60, 53115 Bonn
Location: Endenicher Allee 60, Lipschitz hall
Location: Lennéstr. 2, Seminarraum
Invited Speakers:
- Michael Christ (UC Berkeley)
- Philip Gressman (U. Penn)
- Ian Petrow (UCL)
- James Wright (U. Edinburgh)
- Ruixiang Zhang (UC Berkeley)
- Polona Durcik (Chapman University)
- Dóminique Kemp (UW Madison/IAS/Princeton)
- Dominique Maldague (MIT)
- Hong Wang (UCLA)
Location: Lipschitz hall, Endenicher Allee 60, 53115 Bonn
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: Endenicher Allee 60, Lipschitz hall
Invited Speakers:
- Jonathan Bennett (University of Birmingham)
- Xiumin Du (Northwestern University)
- Malabika Pramanik (UBC)
- Andreas Seeger (UW Madison)
Location: Lipschitz hall, Endenicher Allee 60, 53115 Bonn
Location: Endenicher Allee 60, Lipschitz hall
Location: MPIM Lecture Hall
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
August 2024
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
September 2024
Location: MPIM Lecture Hall
Invited Speakers:
• Alice Guionnet (Ecole Normale Supérieure Lyon)
• Ioan Manolescu (University of Fribourg)
• Eliran Subag (Weizmann Institute of Science, Israel)
• Simone Warzel (Technical University of Munich)
Location: Lipschitz hall, Endenicher Allee 60, 53115 Bonn
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Invited Speakers:
- Adolfo Arroyo-Rabasa (Catholic University of Louvain)
- Annika Bach (Eindhoven University of Technology)
- Giulia Bevilacqua (University of Pisa)
- Elise Bonhomme (Free University of Brussels)
- Camilla Brizzi (Technical University of Munich)
- Elia Brué (Bocconi University, Milan)
- Leon Bungert (University of Würzburg)
- Sara Daneri (University of L’Aquila)
- Cristiana De Filippis (University of Parma)
- Annette Dumas (University Claude Bernard, Lyon )
- Katharina Eichinger (Polytechnic School, Paris)
- Xavier Fernandez-Real (EPFL - Swiss Federal Institute of Technology, Lausanne)
- André Guerra (Institute for Theoretical Studies, ETH, Zurich)
- Jasper Hoeksema (Eindhoven University of Technology)
- Domenico Angelo La Manna (University of Naples, Federico II)
- Tim Laux (University of Regensburg)
- Alice Marveggio (HCM, Bonn)
- Roberta Marziani (University of L’Aquila)
- Mircea Petrache (Catholic Chile Univesity, Santiago)
- Simone Rademacher (Ludwig Maximilian University of Munich)
- Sebastian Schwarzacher (Charles University, Prague)
- Bozhidar Velichkov (University of Pisa)
Location: Endenicher Allee 60, Lipschitz hall
Location: Lecture Hall (Room 0.109), b-it building, Friedrich-Hirzebruch-Allee 6
October 2024
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
November 2024
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)