Events

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Monday, 27 March
— no events scheduled today —
Tuesday, 28 March
Time Speaker Title Location
15:15 - 16:15 Prof. Dr. Melanie Rupflin
University of Oxford
Analysis Seminar
Title T.B.A.
HG G 43 
Wednesday, 29 March
Time Speaker Title Location
15:45 - 16:45 Alexandre Martin
Universität Wien
Geometry Seminar
On the acylindrical hyperbolicity of certain Artin groups 
HG G 43 
Abstract: Acylindrical hyperbolicity is a far-reaching generalisation of the notion of relative hyperbolicity that encompasses many classes of groups of interest in geometry and geometric group theory. In this talk, I will present a powerful but easy to apply criterion to show the acylindrical hyperbolicity of certain groups acting on CAT(0) cube complexes. As an application, I will explain how such a criterion can be used to show the acylindrical hyperbolicity of certain Artin groups. (Joint work with Indira Chatterji)
16:15 - 17:15 Prof. Dr. Mathias Fink
ESPCI Paris
Zurich Colloquium in Applied and Computational Mathematics
Wave Control and Holography with Time Transformations 
Y27  H 25
Abstract: Because time and space play a similar role in wave propagation, wave control can be achieved or by manipulating spatial boundaries or by manipulating time boundaries. Here we emphasize the role of time boundaries manipulation. We show that sudden changes of the medium properties generate instant wave sources that emerge instantaneously from the entire wavefield and can be used to control wavefield and to revisit the holographic principles and the way to create time-reversed waves. Experimental demonstrations of this approach with water waves will be presented and the extension of this concept to acoustic and electromagnetic waves will be discussed. More sophisticated time manipulations can also be studied in order to extend the concept of photonic crystals and wave localization in the time domain.
17:15 - 18:15 Nicolas Matte Bon
ETH Zürich
Seminar on Stochastic Processes
Extensive amenability of group actions 
Y27  H 12
Abstract: A group is amenable if the spectral radius of any symmetric random walk on it is equal to one. This is only one among the many equivalent characterisations of this property, that make it play a role in many aspects of group theory. Nevertheless, deciding wether a group is amenable or not can be a difficult problem. Extensive amenability is a property of group actions, first considered by Juschenko and Monod, that leads to a method to prove amenability of groups. I will explain this property and give a a probabilistic reformulation of it, then explain this method and illustrate it by proving amenability of some groups of interval exchange transformations. Finally I will highlight the current limits of this method and some related open questions. Talk based on a joint work with Juschenko, Monod, and de la Salle.
Thursday, 30 March
Time Speaker Title Location
15:15 - 16:15 Robert Seiringer
IST Austria
Talks in Mathematical Physics
Stability of quantum many-body systems with point interactions 
HG G 43 
Abstract: We present a proof that a system of N fermions interacting with an additional particle via point interactions is stable if the ratio of the mass of the additional particle to the one of the fermions is larger than some critical m∗. The value of m∗ is independent of N and turns out to be less than 1. This fact is of relevance for the stability of fermionic gases in the unitary limit. We also present a rigorous version of the Tan relations valid for all wave functions in the domain of the Hamiltonian of this model.
17:15 - 18:15 Fred Espen Benth 
University of Oslo
Talks in Financial and Insurance Mathematics
Cointegration in continuous-time for factor models 
HG G 43 
Abstract: Based on some empirical evidence and stochastic models from the freight market, we propose a framework for cointegration in continuous-time. We study forward pricing, relevant in commodity markets, and how cointegration in the spot market affects the forward markets. We share some thoughts on particular cases like CARMA, polynomial and Levy stationary processes. Finally, we propose a notion of cointegration for infinite dimensional processes. The presentation is based on joint work with Andre Suess (Barcelona and Zuerich).
Friday, 31 March
Time Speaker Title Location
14:15 - 15:15 Prof. Dr. Yiannis Petridis
University College London
Number Theory Seminar
Arithmetic Statistics of modular symbols 
HG G 43 
Abstract: Mazur, Rubin, and Stein have recently formulated a series of conjectures about statistical properties of modular symbols in order to understand central values of twists of elliptic curve L-functions. Two of these conjectures relate to the asymptotic growth of the first and second moments of the modular symbols. In joint work with Morten S. Risager we prove these on average using analytic properties of Eisenstein series twisted with modular symbols. We also prove another conjecture predicting the Gaussian distribution of normalized modular symbols ordered according to the size of the denominator of the cusps.
16:30 - 17:45 Jason van Zelm
University of Liverpool
Algebraic Geometry and Moduli Seminar
Nontautological bielliptic cycles 
HG G 43 
Abstract: Tautological classes are geometrically defined classes in the Chow ring of the moduli space of curves which are particularly well understood. The classes of many known geometrically defined loci were proven to be tautological. A bielliptic curve is a curve with a 2-to-1 map to an elliptic curve. In this talk we will build on an idea of Graber and Pandharipande to show that the closure of the locus of bielliptic curves in the moduli space of stable curves of genus g is non-tautological when g is at least 12.

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29.03.2017
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