var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-61"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-59"><img src="//www2.math.ethz.ch/smsjs/images/arrow_right.png"/></a></div>    <div class="sms_title">      <span style="float: left;">SMS</span>      <span>SWISS MATHEMATICAL SOCIETY</span>      <span style="float: right;">SMG</span>    </div>    <div class="sms_info">      <span style="float: left; width: 250px;">Bulletin no. 2</span>      <span style="float: right; text-align:right; width: 250px;">26.2 - 1.3.2024</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2024</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, February 26      </div>      <div class="day_content">        <div class="day_content_item no_event">        No events scheduled today!        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, February 27      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/annonces/groupes-geometrie">Groupes et Géométrie </a></div><br /><div class="event_speaker"> Luis Paris (Université de Bourgogne)</div><div class="event_title">Dyer groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Coxeter groups and right-angled Artin groups share the same solution to the word problem: that given by Tits for Coxeter groups and that given by Green for right-angled Artin groups. This algorithm goes beyond the simple solution to the word problem, since it allows to determine whether an expression is reduced or not, and it is an essential tool for defining normal forms in both families. Hence the question: what do these two families of groups have in common that makes them have the same solution to the word problem? The answer sits inside Dyer\'s thesis published in 1990 where a family of groups is described which contains both, Coxeter groups and right-angled Artin groups. We prove that all Dyer groups have this solution to the word problem and that any group which admits such a solution is a Dyer group up to a small modification of the definition. The coincidence does not stop there because these two families of groups share many other properties. This talk will be a propaganda for Dyer\'s groups.</div><div class="event_time">10:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/schools/sb/research/math/statistics-seminars/">Statistics Seminar </a></div><br /><div class="event_speaker"> Noam Razin (Tel Aviv University)</div><div class="event_title">Two Analyses of Modern Deep Learning: Graph Neural Networks and Language Model Finetuning <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The resurgence of deep learning was largely driven by architectures conceived in the 20th century trained using labeled data. In recent years deep learning has undergone paradigm shifts characterized by new architectures and training regimes. Despite the popularity of the new paradigms their theoretical understanding is limited. In this talk I will present two recent works analyzing aspects of modern deep learning. The first work considers the expressive power of graph neural networks and formally quantifies their ability to model interactions between vertices. As a practical application of the theory I will introduce a simple edge sparsification algorithm that achieves state-of-the-art results. The second work identifies a fundamental vanishing gradients problem that occurs when using reinforcement learning to finetune language models. I will demonstrate the detrimental effects of this phenomenon and present possible solutions. Lastly I will conclude with an outlook on important questions raised by the advent of foundation models and possible tools for addressing them.Works covered in the talk were in collaboration with Nadav Cohen Tom Verbin Hattie Zhou Omid Saremi Vimal Thilak Arwen Bradley Preetum Nakkiran Joshua Susskind and Etai Littwin.</div><div class="event_time">11:15 &bull; EPF Lausanne, GA 3 21</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/annonces/seminaire-danalyse-numerique">Séminaire d\'Analyse Numérique </a></div><br /><div class="event_speaker"> Philipp Birken (University of Lund)</div><div class="event_title">Time adaptive waveform methods for dynamic multiphysics problems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We discuss partitioned time-integration of dynamic multiphysics problems, which commonly exhibit a multiscale behavior, requiring independent time-grids. The ideal method for solving these problems allows independent and adaptive time-grids, higher order time-discretizations, is fast and robust, and allows the coupling of existing subsolvers, executed in parallel.Waveform relaxation (WR) methods can potentially have all of these properties. These iterate on continuous-in-time interface functions, obtained via suitable interpolation. This way, one can allow for time adaptivity in the subsolvers. We present a fast and highly robust, second order in time, adaptive WR method. Basis is a Dirichlet-Neumann coupling at the interface, combined with an acceleration technique based on Quasi-Newton methods. As a leading example, we use coupled heat equations and discuss existing convergence results.Numerical results demonstrate the robustness and efficiency of the method for different multiphysics problems.</div><div class="event_time">14:00 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://calendar.google.com/calendar/embed?mode=AGENDA&height=600&wkst=2&bgcolor=%23FFFFFF&src=t36it03v52cus2detrvinlgk18%40group.calendar.google.com&color=%235F6B02&ctz=Europe%2FZurich">Groups, Arithmetic and Algebraic Geometry Seminar </a></div><br /><div class="event_speaker"> Alexei Skorobogatova (Imperial)</div><div class="event_title">On p-primary torsion of the Brauer group in characteristic p <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Let k be a finitely generated field. Relation between the Tate conjecture for divisors and finiteness properties of the Brauer groups of varieties over k is well known, at least for torsion coprime to char(k). Much less is known about p-primary torsion in characteristic p. In a recent paper, D\'Addezio clarified the situation for abelian varieties over fields of positive characteristic. Using similar ideas, I will show that for varieties X and Y satisfying some mild conditions, the cokernel of the map from Br(X) \\oplus Br(Y) to Br(X\\times Y) is a direct sum of a finite group and a p-group of finite exponent (which can be infinite). This implies, for example, that the transcendental Brauer group of surfaces dominated by products of curves has finite exponent.</div><div class="event_time">14:15 &bull; EPF Lausanne, Bernoulli Center, GA 3 34</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Giovanni Canepa (UniGE)</div><div class="event_title">Poisson infinity structures of field theories on manifold with corners <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk I will describe a local Poisson structure (up to homotopy) associated with any field theory defined on manifolds with corners. This is achievedthrough the use of the BFV formalism. The resulting Poisson structure is connected to the algebra of observables. Some examples will be presented,from BF theory to General Relativity. This is a joint work with A. S. Cattaneo.</div><div class="event_time">15:00 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, February 28      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://commonweb.unifr.ch/_Science/Math/Pub/Math/seminars/OSgeom-top.html">Oberseminar Geometrie</a></div><br /><div class="event_speaker"> Filip Misev (Regensburg)</div><div class="event_title">Braids on three strings of maximal four-genus <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />When we look at surfaces embedded in four-dimensional space, regular-ity (smooth/topological) of the embedding matters: The minimal genusof surfaces in the four-dimensional ball with a prescribed knot as theirboundary does not only depend on the knot but also on the regularity ofthe surface’s embedding. Four decades after this discovery, which goesback to Rudolph and to the celebrated work of Freedman, the discrep-ancy between smooth and topological remains difficult to characterizeand to quantify; for example the topological four-genus of torus knots islargely unknown to date.I would like to present a classification of knots obtained as the closuresof braids on three strings whose topological four-genus is maximal (thatis, equal to their classical genus). For the remaining braids on threestrings, we have bounds and some precise calculations.This reports on a project with S. Baader, L. Lewark, and P. Truöl.</div><div class="event_time">10:20 &bull; Université de Fribourg, room Phys 2.52</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.unil.ch/dsa/en/home/menuinst/seminaires--evenements/research-seminars.html">Talks in Actuarial Mathematics </a></div><br /><div class="event_speaker"> Stefano Rizzelli (Universit of Padova)</div><div class="event_title">Inference on marginal expected shortfall under multivariate regular variation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The marginal expected shortfall is arguably one of the most popular measures of systemic risk. The study of its extreme behaviour is particularly relevant for protecting against the risk of severe downturns in global financial markets. In this context, statistical inference is typically based on bivariate extreme-value models for a given financial variable of interest and another that incorporates systemic risk information. However, this disregards the more complex extremal dependence structure among a large number of financial institutions, of which the market is composed. To explicitly account for it, we propose an inferential procedure based on the theory of multivariate regular variation. We derive an approximation formula for the extreme marginal expected shortfall and derive an estimator, of which we also propose a bias-corrected version. We prove their asymptotic normality, which in turn allows the derivation of confidence intervals. A simulation study shows that the new estimators significantly improve the performance of the existing ones and the confidence intervals are very accurate. We showcase the usefulness of the proposed inferential procedure by analysing returns on stocks for financial institutions classified as "Global Systemically Important Banks" or "Domestic Systemically Important Banks" from US and Canada. The statistical results are extended to a general beta-mixing context that accommodates popular time series models with heavy-tailed innovations. This is a joint work with Simone Padoan (Bocconi University) and Matteo Schiavone (University of Padova).</div><div class="event_time">13:30 &bull; EPF Lausanne, Anthropole 3034</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Prof. Dr. Krzysztof Krupinski (Uniwersytetu Wroclawskiego)</div><div class="event_title">On some applications of model theory and topological dynamics <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Model theory is a fast growing branch of mathematical logic with deep interactions with algebra, algebraic geometry, combinatorics, and, more recently, topological dynamics. I will focus on a few interactions with topological dynamics and applications to additive combinatorics. I will discus type-definable components of definable groups, which lead to model-theoretic descriptions of Bohr compactificatios of groups and rings, and also to so-called locally compact models of approximate subgroups and subrings which in turn are crucial to get structural or even classification results about approximate subgroups and subrings. I will discuss my result that each approximate subring has a locally compact model, and mention some structural applications. In contrast to approximate subrings, not every approximate subgroup has a locally compact model. However, Ehud Hrushovski showed that instead it has such a model in a certain generalized sense (with morphisms replaced by quasi-homomorphisms). In order to do that, he introduced and developed local logics and definability patterns. In my recent paper with Anand Pillay, we gave a shorter and simpler construction of a generalized locally compact model, based on topological dynamics methods in a model-theoretic context. I will briefly discuss it, if time permits.</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://calendar.google.com/calendar/embed?mode=AGENDA&height=600&wkst=2&bgcolor=%23FFFFFF&src=t36it03v52cus2detrvinlgk18%40group.calendar.google.com&color=%235F6B02&ctz=Europe%2FZurich">Groups, Arithmetic and Algebraic Geometry Seminar </a></div><br /><div class="event_speaker"> Mathew Satriano</div><div class="event_title">Beyond twisted maps: crepant resolutions of log terminal singularities and a motivic McKay correspondence. <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Crepant resolutions have inspired connections between birational geometry, derived categories, representation theory, and motivic integration. In this talk, we prove that every variety with log-terminal singularities admits a crepant resolution by a smooth stack. We additionally prove a motivic McKay correspondence for stack-theoretic resolutions. Finally, we show how our work naturally leads to a generalization of twisted mapping spaces. This is joint work with Jeremy Usatine.</div><div class="event_time">14:15 &bull; EPF Lausanne</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/aa/?events">Neuchatel - St.Gallen - Zurich Seminar in Coding Theory and Cryptography</a></div><br /><div class="event_speaker">Daniella Bar-Lev (Technion)</div><div class="event_title">The DNA Storage Channel: From Theory to Practice <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In recent years, DNA-based storage systems have emerged as promising solutions for long-term data archival due to their high data density and durability. This talk explores the intricacies of DNA storage, highlighting its advantages and challenges. DNA-based storage possesses distinct characteristics that distinguish it from conventional storage mediums. Synthesized DNA strands contain inherent redundancy due to replication during synthesis and sequencing processes, yet their unordered arrangement introduces complexity to data retrieval. Additionally, synthesis and sequencing introduce errors such as insertions, deletions, and substitutions, posing significant challenges to data integrity. This talk will begin with an examination of the background of DNA storage and the challenges posed by the DNA storage channel. Throughout the presentation, we will emphasize several open problems related to the channel, underscoring the need for innovative solutions to advance DNA storage technology. To bridge theory with application, we will discuss two recent research projects. The first focuses on the DNA coverage depth problem, which aims to reduce both, cost and latency in DNA storage. We will investigate how error-correcting codes and retrieval algorithms impact the sequencing coverage depth and explore how this coverage can be optimized. Additionally, we will explore a scalable end-to-end DNA storage pipeline, integrating deep neural networks and tensor-product based error-correcting codes, significantly improving speed, accuracy, and code rate. These insights contribute to advancing the efficiency and feasibility of DNA storage solutions, setting the stage for future advancements.</div><div class="event_time">15:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/geometry-seminar">Geometry Seminar</a></div><br /><div class="event_speaker">Dr. Miguel Orbegozo Rodriguez (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">Right-veering diffeomorphisms and contact geometry <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Although contact geometry has its origins in the 19th century, it wasn\'t until the 1970s that it began to be studied via topological methods. More recently, in 2002, the Giroux correspondence theorem established, in dimension 3, a close relationship between contact manifolds and open book decompositions (i.e fibered links). This means that properties of contact 3-manifolds can be studied by studying properties of mapping classes of surfaces. In this talk I will start by providing an overview to contact geometry in dimension 3, and introducing one of the most relevant properties, the dichotomy between tight and overtwisted contact structures. This can be studied, by a result of Honda-Kazez-Matic, via right-veering diffeomorphisms of surfaces. I will show that this property is not easy to detect in general before presenting a combinatorial way of detecting it.</div><div class="event_time">15:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/aa/?events">Neuchatel - St.Gallen - Zurich Seminar in Coding Theory and Cryptography</a></div><br /><div class="event_speaker">Vivien Caroline Bammert</div><div class="event_title">Security of Algebraic Geometry Codes in Code-Based Cryptography <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Code-based cryptosystems are promising candidates for post-quantum cryptography, such as the McEliece and Niederreiter cryptosystems. Their security is based on the difficulty of decoding a general linear code. In this thesis, we study the security of algebraic geometry codes in code-based cryptography. These codes include very well-known families like generalized Reed-Solomon, BCH and Goppa codes. Furthermore, they can be described using certain tools, e.g. the theory of algebraic function fields, which we will focus on.</div><div class="event_time">16:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/news-and-events/events/lecture-series/inaugural-introductory-farewell-lectures.html">Farewell Lectures</a></div><br /><div class="event_speaker">Prof. em. Dr. Giovanni Felder (ETH Z&uuml;rich, Switzerland)</div><div class="event_title"><a class="external" href="https://ethz.ch/en/news-and-events/events/details.triangles-quadrilaterals-pentagons.70122.html">Triangles, Quadrilaterals, Pentagons</a></div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG , Room F 30</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, February 29      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Umut Cetin (London School of Economics)</div><div class="event_title">Mathematics of Market Microstructure</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/~palmeran/topsem.html">Séminaire de Topologie et Géométrie </a></div><br /><div class="event_speaker"> Pavol  Severa  (UNIGE)</div><div class="event_title">Braids and quantization (of Poisson-Hopf algebras and related things) <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will explain how the replacement of permutations by braids replaces also groups by Hopf algebras (by passing from "symmetric simplicial objects" to "braided simplicial objects"), and how it gives us a deformation quantization of Poisson brackets on commutative Hopf algebras. This story can be seen as a small corner of Chern-Simons theory with suitable boundary conditions. Based on a joint work with Jan Pulmann.</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://stat.ethz.ch/events/zukost">ZueKoSt: Seminar on Applied Statistics</a></div><br /><div class="event_speaker"> Manuela Brunner (WSL Institute for Snow and Avalanche Research SLF)</div><div class="event_title">Exceptional flood events: insights from three simulation approaches <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Exceptional floods, i.e. flood events with magnitudes or spatial extents occurring only once or twice a century, are rare by definition. Therefore, it is challenging to estimate their frequency, magnitude, and future changes. In this talk, I discuss three methods that enable us to study exceptional extreme events absent in observational records thanks to increasing sample size: stationary and non-stationary stochastic simulation, reanalysis ensemble pooling, and single-model initialized large ensembles. I apply these techniques to (1) study the frequency of widespread floods, (2) quantify future changes in spatial flood extents, (3) estimate the magnitude of floods happening once or twice a century, and (4) shed light on the relationship between future increases in extreme precipitation and flooding. These applications suggest that simulation approaches that substantially increase sample size provide a better picture of flood variability and help to increase our understanding of the characteristics, drivers, and changes of exceptional extreme events. </div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.2</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Dr. Rishabh Gvalani (ETH Zürich)</div><div class="event_title">Mean-field Gibbs measures: Sharp and optimal rates of convergence <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study the invariant Gibbs measure of mean-field interacting diffusions and prove optimal global and local rates of convergence to its thermodynamic limit in the full sub-critical regime of temperatures \\(T>T_c\\) for a large class of potentials. Our proof relies on a non-asymptotic Sanov-type upper bound for the global rate (which is of independent interest itself) combined with an application of Stein\'s method for the local rate. We also apply these techniques to prove sharp exponential concentration inequalities for i.i.d empirical measures in negative Sobolev norms. This is joint work with Matías G. Delgadino (U. T. Austin).</div><div class="event_time">16:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 46</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-financial-and-insurance-mathematics">Talks in Financial and Insurance Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Mehdi Talbi (Université Paris-Cité)</div><div class="event_title">Sannikov’s contracting problem with many Agents <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This work aims to study an extension of the celebrated Sannikov’s Principal-Agent problem to the multi-Agents case. In this framework, the contracts proposed by the Principal consist in a running payment, a retirement time and a final payment at retirement. After discussing how the Principal may derive optimal contracts in the N-Agents case, we explore the corresponding mean field model, with a continuous infinity of Agents. We then prove that the Principal’s problem can be reduced to a mixed control-and-stopping mean field problem, and we derive a semi-explicit solution of the first best contracting problem. This is a joint work with Thibaut Mastrolia and Nizar Touzi.</div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, March 1      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/mpseminar/seminar.html">Séminaire de Mathématique Physique </a></div><br /><div class="event_speaker"> Alexander  van Spaendonck  </div><div class="event_title">Resurgent transseries in quantum mechanics <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It is well known that perturbative series encode information about many – but not necessarily all -- nonperturbative effects and that both can be unified in a so-called ‘transseries’. Such transseries are universally present in physics, but relatively few examples are known in closed form. In this talk I will discuss one-dimensional quantum mechanical oscillators and demonstrate how one obtains a transseries solution for the energy spectrum which contains all instanton corrections in closed form. I’ll subsequently elucidate the resurgent structure of this transseries using alien calculus and demonstrate that in more nontrivial models, these transseries are not ‘minimally resurgent’, but factorize into two distinct transseries structures. This talk is based on joint work with Marcel Vonk. </div><div class="event_time">10:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/anmath/seminars/">Seminar of Analysis </a></div><br /><div class="event_speaker"> Bjoern Bringmann (IAS & Princeton University)</div><div class="event_title">Invariant Gibbs measures for (1 + 1)-dimensional wave maps into Lie groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the wave maps equation for maps from (1+1)-dimensional Minkowski space into a compact Lie group. The Gibbs measure of this model corresponds to a Brownian motion on the Lie group, which is a natural object from stochastic differential geometry. Our main result is the invariance of the Gibbs measure under the wave maps equation and is the first result of this kind for any geometric wave equation. The proof combines techniques from differential geometry, partial differential equations, and probability theory.</div><div class="event_time">14:15 &bull; EPF Lausanne, MA B1 11</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/number-theory-seminar">Number Theory Seminar</a></div><br /><div class="event_speaker">Dr. Yuan Liu (University of Illinois Urbana-Champaign)</div><div class="event_title">On the distribution of class groups — beyond Cohen-Lenstra and Gerth <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Cohen-Lenstra heuristic studies the distribution of the p-part of the class group of quadratic number fields for odd prime p, and Gerth’s conjecture regards the distribution of the 2-part of the class group of quadratic fields. The main difference between these two conjectures is that while the (odd) p-part of class group behaves completely “randomly”, the 2-part of class group does not since the 2-torsion of the class group is controlled by the genus field. In this talk, we will discuss a new conjecture generalizing Cohen-Lenstra and Gerth’s conjectures. The techniques involve Galois cohomology and embedding problems of global fields. If time permits, we will also discuss how to prove a function field analog of this new conjecture, by counting points on the Hurwitz spaces.</div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>  </div>  <div id="sms_footer">    address: Alessandra Naldi Windler, Departement Mathematik, HG G 51.4, ETH Zurich, Raemistrasse 101, CH-8092 Zurich<br />    email: <a href="mailto:bulletin@math.ch">bulletin@math.ch</a> | phone: +41 44 632 3684 | url: <a href="https://math.ch">https://math.ch</a>    <br /><br /><img src="//www2.math.ethz.ch/smsjs/sms_logo.gif" width="150" alt="SMS/SMG Logo" title="SMS/SMG Logo" />  </div></div>';