May 2024
Location: MPIM Lecture Hall
Location: MPIM Lecture Hall
Location: HIM lecture hall (Poppelsdorfer Allee 45, Bonn)
Location: MPIM Lecture Hall
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 Seminar Room
Location: MPIM Seminar Room
Location: Endenicher Allee 60, seminar room 0.008
Abstract:
I will briefly introduce noncommutative geometry and one of its main technical devices, unbounded KK-theory, and then discuss how dynamical systems can be represented therein. One important concept for this purpose is equivariant KK-theory. In the development of unbounded KK-theory, an aspect which has been left unresolved is the definition of equivariance. One reason for this is that the natural definition fails to capture all the degrees of freedom available in the usual, bounded equivariant KK-theory. This is apparent already in the commutative case, as we shall see. In light of the forgoing, conformal geometry will be briefly introduced and I will discuss the definition of conformally equivariant unbounded KK-theory. I also will touch on ongoing work which uses these tools to analyse group actions on parabolic geometries and more general dynamical systems.
Location: Seminarraum MPI
Abstract:
For any finite k-group scheme G acting rationally on a k-variety X, if the action is generically free then the dimension of Lie (G) is upper bounded by the dimension of the variety.This inequality turns out to be also a sufficient condition for the existence of such actions, when k is a perfect field of positive characteristic and G is infinitesimal commutative trigonalizable. These group schemes are non-reduced and arise only in positive characteristic. After presenting the main objects involved and overviewing the motivation for this problem, we will explain the result in the case of actions of the p-torsion of a supersingular elliptic curve.
Location: MPIM Lecture Hall
Location: Endenicher Allee 60, Lipschitz hall
Location: MPIM Seminar Room
Location: Endenicher Allee 60, Lipschitz hall
Location: Endenicher Allee 60, seminar room 0.008
Abstract: In diesem Vortrag wird Juri Langer das Thema seiner Bachelorarbeit vorstellen.
(Vortrag auf Deutsch)
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)