var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-14"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-12"><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. 9</span>      <span style="float: right; text-align:right; width: 250px;">15.4 - 19.4.2024</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, April 15      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde">Bernoullis Tafelrunde</a></div><br /><div class="event_speaker"> Beat Zurbuchen (ETHZ)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde/detail/bernoullis-tafelrunde-beat-zurbuchen-ethz/">Automorphic forms in Number Theory</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Automorphic forms are central objects in number theory at least since Riemann\'s proof of the functional equation for the zeta function. From a modern point of view, automorphic forms are functions on certain homogeneous spaces which correspond to unitary representations of an adelic symmetry group in a natural way. Langlands conjectured that such representations correspond to certain representations of the Galois group. This talk attempts to explain this correspondence for the special case of Hecke characters and, if time permits, modular forms. abstract</div><div class="event_time">12:15 &bull; Universität Basel, Spiegelgasse 5, Seminar Room 05.002</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/mpseminar/seminar.html">Séminaire de Mathématique Physique </a></div><br /><div class="event_speaker"> Raphael Ducatez (Université Claude Bernard Lyon 1)</div><div class="event_title">Full large deviation principles for the largest eigenvalue of sub-Gaussian Wigner matrices <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Joint work with A Guionnet and N CookWe establish precise estimates for the probability of rare events of the largest eigenvalue of Wigner matrices with sub-Gaussian entries. In contrast to the case of Wigner matrices with heavier tails, where deviations are governed by the appearance of a few large entries, and the sharp sub-Gaussian case that is governed by the collective deviation of entries in a delocalized rank-one pattern, we show that in the general sub-Gaussian case that deviations can be caused by a mixture of localized and delocalized changes in the entries. Our key result is a finite-N approximation for the probability of rare events by an optimization problem involving \\emph{restricted annealed free energies} for a spherical spin glass model. This allows us to derive full large deviation principles for the largest eigenvalue in several cases, including when the law of the matrix entries is compactly supported and symmetric, as well as the case of randomly sparsified GOE matrices.</div><div class="event_time">16:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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/OSTopologie/OSTopologie.html">Oberseminar Topologie </a></div><br /><div class="event_speaker"> David González Álvaro (Universidad Politécnica de Madrid)</div><div class="event_title">Examples of Ric_2>0 manifolds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk we will discuss the construction of Ric_2>0 metrics on closed manifolds of dimensions 10, 11, 12, 13 and 14. These include S^6 x S^7, S^7 x S^7 and infinitely many homeomorphism types in dimension 13. The main new ingredient is a notion for homogeneous bundles which generalizes the concept of fatness and, together with other assumptions, ensures the existence of Ric_2>0 metrics on the total space of the bundle. Further examples are obtained by considering biquotients of the corresponding homogeneous spaces. This is joint work with Jason DeVito, Miguel Dom&iacute;nguez-V&aacute;zquez and Alberto Rodr&iacute;guez-V&aacute;zquez.</div><div class="event_time">17:00 &bull; Université de Fribourg, 0.05 PER23</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_be"><a class="external" href="https://www.unibe.ch">Universität Bern</a></div><div class="event_type"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Mathematisches Kolloquium </a></div><br /><div class="event_speaker"> Alexander Gutermann (Bar-Ilan University)</div><div class="event_title">On the values of the permanent function <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Two important functions in matrix theory, determinant and permanent, look very similar: det(A) is the sum over all permutations pi of a sign(pi) times the product over all i of a_{i,pi(i)}, and per(A) is the same but without the factor sign(pi). These functions are in the center of the investigations for several centuries because of their numerous applications and a number of open mathematical problems. For example, while the computation of the determinant can be done in a polynomial time, it is still an open question, if there are such algorithms to compute the permanent. Consequently, the question of the values that permanent can achieve, is actual. We will talk about recent results in this direction including the following two of our works. In 1974 Wang [4, Problem 2] posed a question to find a decent upper bound for |per (A)| if A is a square (&#8722;1, 1)-matrix of rank k, see also Problem 6 in [3, Chapter 8.4]. In 1985 Kräuter [2] conjectured a certain upper bound. We prove the Kräuter’s conjecture and thus obtain the complete answer to the Wang’s question as well as characterized the matrices with the maximal possible permanent for each value of k. We improve the Brualdi-Newman bound [1] for the consequent values of permanent of (0, 1) matrices. The talk is based on the joint works with M. Budrevich and K. Taranin [1] R.A. Brualdi, M. Newman, Some theorems on permanent, J. Res. Natl. Bur. Stand., Sect. B 69 (3) (1965) 159–163. [2] A.R. Kräuter, Recent results on permanents of (+1, -1)-matrices, Ber. No. 249, Berichte, 243-254, Forschungszentrum Graz, Graz, 1985. [3] H. Minc, Permanents, Encyclopedia of Mathematics and its Applications, V. 6, 1978. [4] E.T.H. Wang, On permanents of (+1, -1)-matrices, Israel J. Math., 18 (1974) 353-361.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Lecture Room B6</div>        </div>        <div class="day_content_item important"><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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Dr. Miguel Moreira (MIT)</div><div class="event_title">The cohomology ring of moduli spaces of 1-dimensional sheaves on CP2 <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The cohomology of moduli spaces of 1-dimensional sheaves, together with a special filtration called the perverse filtration, can be used to give an intrinsic definition of (refined) Gopakumar-Vafa invariants. While there are methods to calculate the Betti numbers of these moduli spaces in low degree, understanding the perverse filtration is more challenging. One way to compute it is to fully determine the cohomology ring. In this talk I will explain an approach to describing the cohomology rings of moduli spaces and moduli stacks in terms of generators and relations, which allowed us to determine them for curve classes up to degree 5 (for moduli spaces) and 4 (for moduli stacks). I will explain the P=C conjecture, which is an analogue of the P=W conjecture in a Fano and compact setting. This is joint work with Yakov Kononov, Woonam Lim and Weite Pi.</div><div class="event_time">17:30 &bull; Zoom</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, April 16      </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"> Adélie Garin (EPFL)</div><div class="event_title">When TDA meets geometric group theory: A stratification of barcode space using Coxeter complexes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />At the intersection of data science and algebraic topology, topological data analysis (TDA) is a recent field of study that provides robust mathematical, statistical and algorithmic methods for analysing the topology and geometry underlying complex data. TDA has proven useful in many applications, including biology, materials science and climate science, and continues to evolve rapidly. Barcodes are frequently used invariants in TDA. They provide topological summaries of the persistent homology of a filtered space. Understanding the structure and geometry of the barcode space is therefore crucial for applications. In this talk, we use Coxeter complexes to define new coordinates on the barcode space. These coordinates define a stratification of the barcode space with n bars, where the highest dimensional strata are indexed by the elements of the symmetric group. This creates a bridge between the fields of TDA, geometric group theory and permutation statistics, which could be exploited by researchers in each field.This presentation is based on joint work with B. Brück. No prerequisites on TDA or Coxeter complexes are required.</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_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"> Adrien  Laurent (INRIA Rennes)</div><div class="event_title">The geometric properties of exotic aromatic Butcher-series in stochastic backward error analysis <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Butcher series are a strong tool for the backward error analysis of ordinary and stochastic differential equations. After introducing the standard B-series, their exotic and aromatic extensions, and some of their numerical applications, we will ask ourselves the question: are these B-series just a tool for tedious calculations or are they interesting beyond their numerical applications? We will show that exotic aromatic B-series satisfy a universal geometric property of equivariance, which confirms that they are a natural geometric object that is interesting not only from the numerical point of view. If time allows, we shall quickly discuss the extension of exotic aromatic B-series to the creation of methods on manifolds.</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"> Francesco Denisi (IMJ-PRG)</div><div class="event_title">The pseudo-effective cone of a hyper-Kähler manifold and polygons of Newton-Okounkov type <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Hyper-Kähler (HK) manifolds form one of the three building blocks of compact Kähler manifolds with vanishing first (real) Chern class. In recent years, there has been a considerable effort by many mathematicians to understand as much as possible about the geometry of these varieties. Despite everything, the positivity of divisors is one of the least understood things in HK geometry. The purpose of this talk is to discuss some results about the positivity of divisors on HK manifolds, which, in some sense, generalise some results from the theory of smooth projective surfaces and provide further credibility to the heuristic that linear series on HK manifolds behave very much like in the surface case.</div><div class="event_time">14:15 &bull; EPF Lausanne, MA A1 10</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/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker"> Mario  Gauvrit  (Université Paris Cité)</div><div class="event_title">Morse index stability for Yang-Mills connections <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We investigate Morse index stability for a sequence of Yang-Mills connections on closed 4-manifolds under bubble-tree convergence. As critical points of a conformally invariant energy, Yang-Mills connections share close ties with harmonic maps in various aspects. Simultaneously, their analysis is simpler as long as we work in an appropriate gauge, the so-called Coulomb gauge. Motivated by applications in constructing non-stable solutions of the Yang-Mills equations, this work extends recent methods developed by Da Lio-Gianocca-Rivière for index stability to the Yang-Mills framework, using sharp decay estimates to prove that the neck regions account for a positive contribution to the second variation.</div><div class="event_time">15:15 &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_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"> Guilhem Semerjian (ENS)</div><div class="event_title">Matrix denoising via low-degree polynomials <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 discuss the additive version of the matrix denoising problem, where a random symmetric matrix S has to be inferred from the observation of Y=S+Z, with Z an independent random matrix modeling a noise. Systematic approximations to the Bayes-optimal estimator of S can be built by considering polynomial estimators. When the prior distributions on S and Z are orthogonally invariant this procedure allows to recover asymptotically the estimator introduced by Bun, Allez, Bouchaud and Potters in 2016. It also opens the way to the discussion of finite-size corrections, and to non-orthogonally invariant priors. A special case of particular interest occurs when S has a Wishart distribution, the denoising problem being then a simplified version of the extensive rank matrix factorization problem.Based on arXiv:2402.16719</div><div class="event_time">15:15 &bull; EPF Lausanne, CM 0 13</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/mat075.1">Zurich Graduate Colloquium</a></div><br /><div class="event_speaker">Yuriy Tumarkin (Universität Zürich)</div><div class="event_title">What is... a translation surface? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />\'\'If you take a square and glue the opposite sides together, you get a flat torus. What happens if you start with a different polygon instead, say a regular octagon? The result is a translation surface, a central object in the field of Teichmüller Dynamics. Of particular interest is the straight-line flow on a translation surface, a simple to define dynamical system that arises from the study of billiards in polygons. In this talk I will give a friendly introduction to a few of the key concepts of the field, such as the moduli space of translation surfaces, and the idea of using renormalisation to study the dynamics on a translation surface.</div><div class="event_time">16:30 &bull; UZH Zentrum, Building KO2, Room F 150</div>        </div>        <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://www.unifr.ch/math/de/info/kolloquium.html">Colloquium </a></div><br /><div class="event_speaker"> David González Álvaro (Universidad Politécnica de Madrid)</div><div class="event_title">Spaces with lower curvature bounds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk we shall review a few of the many existing notions of curvature in Riemannian and metric geometry, together with some of the main achievements and current lines of research. We will put special focus on manifolds of positive sectional curvature and those of positive Ricci curvature, and also on certain curvature conditions which interpolate between them.</div><div class="event_time">17:15 &bull; Université de Fribourg, room Phys 2.52</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, April 17      </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"> Jun Nonaka (Waseda)</div><div class="event_title">A sequence of &#960;/3-equiangular hyperbolic polyhedra <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A polyhedron is called &#960;/k-equiangular if all its dihedral angles are equalto &#960;/k ( k &#8712; N ). In this talk, we will first introduce some known resultsabout such polyhedra in hyperbolic spaces. Then, we will construct asequence of &#960;/3-equiangular three-dimensional hyperbolic polyhedra dif-ferent from the sequence Atkinson found in 2009. We will also determinethe volumes of some of these polyhedra</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_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. Sébastien Biebler (Université Paris Cité)</div><div class="event_title">Non-density of hyperbolicity in complex dynamics in several variables <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />One of the main goals in the theory of dynamical systems is to describe the dynamics of a &quot;typical&quot; map. For instance, in the case of diffeomorphisms of a given manifold, it was conjectured by Smale in the 60s that uniform hyperbolicity was generically satisfied. This hope was however fast discouraged by exhibiting dynamical systems displaying in a robust way dynamical configurations which are obstructions to hyperbolicity: robust homoclinic tangencies (this is the so-called Newhouse phenomenon) and robust heterodimensional cycles. In this talk, I will explain these phenomena and their extensions to the complex setting. In particular, I will show how to construct robust heterodimensional cycles in the family of polynomial automorphisms of C^3. The main tool is the notion of blender coming from real dynamics.</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_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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Danilo Lewanski (University of Trieste)</div><div class="event_title">A fair amount of weighted intersection numbers summing up to zero <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Via virtual localisation techniques, Johnson, Pandharipande and Tseng proved that the integral of the Hodge class over the moduli space of admissible covers vanishes under certain sufficient technical conditions: either strong negativity or negativity together with boundedness would suffice. What happens when these conditions are lifted? The answer (in a certain setting) was provided in previous work with Borot, Do, Karev and Moskovsky: the vanishing of a single summand gets replaced by the vanishing of the sum of many. This was achieved as a byproduct of the topological recursion procedure. By deformation techniques in topological recursion, other three families of these relations arose, two of which genus dependent.Based on joint work with Gaëtan Borot and Maksim Karev, tested thanks to the admcycles Sage package.</div><div class="event_time">13:30 &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_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"> Marius Tiba</div><div class="event_title">Erdos covering systems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Since their introduction by Erdos in 1950, covering systems (that is, finite collections of arithmetic progressions that cover the integers) have been extensively studied, and numerous questions and conjectures have been posed regarding the existence of covering systems with various properties. In 1950, Erdos asked if there exist covering systems with distinct arbitrary large moduli.  In 1965, Erdos and Selfridge asked if there exist covering systems with distinct odd moduli. In 1967, Schinzel conjectured that in any covering system there exists a pair of moduli, one of which divides the other. In 2015, Hough resolved Erdos\' problem showing that a finite collection of arithmetic progressions with distinct sufficiently large moduli does not cover the integers. We established a quantitative version of Hough\'s theorem estimating the density of the uncovered set, thus answering a question posed by Filaseta, Ford, Konyagin, Pomerance and Yu from 2007. Additionally, we resolved the Erdos-Selfridge problem in the square free case as well as Schinzel\'s conjecture in full generality. In this talk, we discuss these results and present a gentle exposition of the methods used. This talk is based on joint work with Paul Balister, Bela Bollobas, Rob Morris and Julian Sahasrabudhe.</div><div class="event_time">14:15 &bull; EPF Lausanne,  CM 1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/analysis/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker"> Anuj Kumar (UC Berkeley)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-anuj-kumar-uc-berkeley/">Sharp nonuniqueness of the transport equation with Sobolev vector fields</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We construct nonunique solutions of the transport equation in the class $L^\\infty$ in time and $L^r$ in space for divergence free Sobolev vector fields $W^{1, p}$. We achieve this by introducing two novel ideas: (1) In the construction, we interweave the scaled copies of the vector field itself. (2) Asynchronous translation of cubes, which makes the construction heterogeneous in space. These new ideas allow us to prove nonuniqueness in the range of exponents beyond what is available using the method of convex integration and sharply matchwith the range of uniqueness of solutions from Bruè, Colombo, De Lellis \'21.</div><div class="event_time">14:15 &bull; Universität Basel, Online via Zoom</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"> Isacco Nonino (University of Glasgow)</div><div class="event_title">Smooth structures on non-compact 4-manifolds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />When studying smooth structures on a 4-dimensional topological manifold M, there are three main topics one has to cover: existence, uniqueness and behavior of their diffeotopy groups.I will explain the reasons why the 4 dimensional case is so interesting and wild, and remark the striking difference between the compact and non-compact settings.I will then give an overview on the recent work on diffeotopy groups of exotic smoothings of R4, and show how the results were generalized to a wider class of non-compact 4 manifolds.</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://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sam/news-and-events/zhacm-colloquia">Zurich Colloquium in Applied and Computational Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Vincent Perrier (Inria, France)</div><div class="event_title">How to preserve a divergence or a curl constraint in a hyperbolic system with the discontinuous Galerkin method <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Some hyperbolic systems are known to include implicit preservation of differential constraints: these are for example the time conservation of the vorticity for the first order wave system or divergence preservation for the Maxwell system or the induction equation. In this talk, I will address this problem with the classical discontinuous Galerkin method. Based on discrete de-Rham ideas, I will show that by considering an adapted approximation space (but still discontinuous) for vectors , divergence or curl can be easily preserved under mild assumption on the numerical flux</div><div class="event_time">16:00 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room E 1.2</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://memento.epfl.ch/event/probability-and-stochastic-analysis-seminar/">Probability (and Stochastic Analysis) Seminar </a></div><br /><div class="event_speaker"> Weijun  Xu  (Beijing)</div><div class="event_title">Periodic homogenisation for 2D gPAM <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider periodic homogenisation problem for two dimensional generalised parabolic Anderson model, a model problem of a singular SPDE beyond Da Prato - Debussche trick. The goal is to understand how the two singular limiting procedures, homogenisation and renormalisation, interact with each other. One key ingredient is to identify a suitable ansatz uniform in the homogenisation parameter in a nontrivial SPDE setting. Based on a joint work with Yilin Chen (PKU) and Ben Fehrman (LSU).</div><div class="event_time">16:00 &bull; EPF Lausanne, Bernoulli Center</div>        </div>        <div class="day_content_item cancelled"><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/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Prof. Dr. Vincent Vargas (Universität Genf)</div><div class="event_title">CANCELLED: Harmonic analysis of Gaussian multiplicative chaos on the circle <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Gaussian multiplicative chaos (GMC) on the circle is a canonical (random) multifractal measure on the circle which appears in a wide variety of contexts and most recently in relation to Liouville conformal field theory. In this talk, I will present the first results concerning the decay and renormalization of the Fourier coefficients of GMC. In particular, one can show that GMC is a so-called Rajchman measure which means that its Fourier coefficients go to zero when the frequency goes to infinity. Numerous questions remain open. Based on a joint work with C. Garban.    </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">        Thursday, April 18      </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 Çetin (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/math/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Nick Nussbaum (Cologne University)</div><div class="event_title">The Path Integral Perspective of CFT <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The presence of symmetries in a QFT is one of the most important characteristics of any theory. As such, understanding these symmetries and their consequences provides a very powerful tool to understand and solve QFTs. One of the most exemplary realizations of this principle are QFTs with so-called conformal symmetry. These conformal field theories notably constitute a fundamental pillar of modern physics and play a fundamental role from the theory of quantum phase transitions to quantum gravity and the standard model. In this mini-lecture course, I will explain how we can maximizes the symmetry principle by taking the path integral perspective, in contrast to the usually presented algebraic viewpoint. Amazingly, this viewpoint  yields a very clear understanding and way of thinking about CFTs. Our guiding principle is going to be the symmetry conundrum of the path integral and we will see that many of the special properties and concepts (like the distinction between operators and fields, which can often be a source of confusion) of CFT are easily understood from this perspective. As such, I will speak about conformal symmetry, the path  integral with symmetries, topological operators, radial quantization and more, depending on the time. The lecture is both aimed at students with knowledge in QFT who want to learn about CFT and advanced students and experts, who I hope will gain some new insights and deepen</div><div class="event_time">10:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</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"> Kamil Rychlewicz (ISTA)</div><div class="event_title">Equivariant cohomology and rings of functions <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In topology of manifolds, there is a long history of theorems which relate global topological invariants to local behavior of vector fields, functions or group actions. This dates back to Poincare-Hopf, but many important results have been proved since, with Morse theory, Bott residue formula for complex manifolds and Bia&#322;ynicki-Birula decomposition for algebraic varieties being notable examples.The classical work of Carrell–Liebermann and Akyildiz goes further and sees the whole cohomology ring as a ring of functions on a thick point, zero of a vector field. In a joint work with Tamas Hausel we generalize the work of Brion and Carrell (for Borel of SL_2) and show how to see the equivariant cohomology as a ring of function for quite general setups.I will start the talk by recalling the classical results, and present the newest developments in the field. This allows us to see geometrically the spectra of equivariant cohomology of classical spaces like flag or Schubert varieties. I will also show how we might be able to tackle the cohomology rings of spherical varieties, extract some information for singular varieties, and how much can be said when we replace cohomology with K-theory.</div><div class="event_time">14:15 &bull; EPF Lausanne,  CM 1 517</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"> Livio  Ferretti  (UniGe)</div><div class="event_title"> The monodromy group of a positive braid, and invariant framings <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The geometric monodromy group is a classical yet rather poorly understood topological invariant of isolated plane curve singularities. In this talk we will discuss a generalization of it to the setting of positive braids and see how working in this wider context can help understanding the original invariant of singularity theory. In particular we obtain that, for irreducible singularities not of type An, up to finitely many exceptions the geometric monodromy group is determined by two simple knot invariants: the genus and the Arf invariant. Our main technical tool are invariant framings on surfaces. If time permits, we will end with a discussion on the application of such techniques to the study of more general fibred links.</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, April 19      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/seminar-in-numerical-analysis">Seminar in Numerical Analysis</a></div><br /><div class="event_speaker"> Barbara Verfürth (University of Bonn)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-in-numerical-analysis-barbara-verfuerth-university-of-bonn/">Multiscale wave propagation in time-varying media</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In the last years, there has been an increasing interest in time-modulated materials to obtain enhanced properties. As mathematical model, we study the classical wave equation with time-dependent coefficient, which may also include spatial multiscale features. Based on joint work with Bernhard Maier, we present a numerical multiscale method for spatially multiscale, (slowly) time-evolving coefficients. The method is inspired by the Localized Orthogonal Decomposition (LOD) and entails time-dependent multiscale spaces. We provide a rigorous a priori error analysis for the considered setting. Numerical examples illustrate the theoretical findings and investigate an adaptive approach for the computation of the time-dependent basis functions. On the other hand, we will also briefly discuss the setting of spatially homogeneous, temporal multiscale coefficients. (Higher-order) multiscale expansions may help to interpret effective physical material properties and are numerically illustrated. For further information about the seminar, please visit this webpage .</div><div class="event_time">11:00 &bull; Universität Basel</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"> Giuseppe Maria Coclite (Polytechnic University of Bari)</div><div class="event_title">Nonlinear Peridynamic Models <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Some materials may naturally exhibit  singularity phenomena  such as cracks or other manifestations as a result of scale effects and long range interactions.  Peridynamic theory models such behavior introducing a new nonlocal framework for the basic equations of continuum mechanics. In this lecture we consider a nonlinear peridynamic model and discuss its qualitative properties and well-posedness in suitable fractional Sobolev spaces.Those results were obtained in collaboration with A. Coclite (Bari), N. Dimola (Milano), S. Dipierro (Perth), G. Fanizza (Casamassima), L. Lopez (Bari), F. Maddalena (Bari),  M. Romano (Bari), S. Pellegrino (Bari), T. Politi (Bari), and E. Valdinoci (Perth).</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">Prof. Dr. Mladen Dimitrov (Université de Lille)</div><div class="event_title">On the Geometry of the Eigencurve <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We will give an overview of the local geometry of the Coleman-Mazur eigencurve at classical points.If time permits we will explain possible generalizations in higher dimension, namely in the Hilbert modular setting.</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 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">ZüKoSt Zürcher Kolloquium über Statistik</a></div><br /><div class="event_speaker"> Joshua  Warren  (Yale University)</div><div class="event_title">A Bayesian framework for incorporating exposure uncertainty into health analyses with application to air pollution and stillbirth <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Abstract:  Studies of the relationships between environmental exposures and adverse health outcomes often rely on a two-stage statistical modeling approach, where exposure is modeled/predicted in the first stage and used as input to a separately fit health outcome analysis in the second stage. Uncertainty in these predictions is frequently ignored, or accounted for in an overly simplistic manner when estimating the associations of interest. Working in the Bayesian setting, we propose a flexible kernel density estimation (KDE) approach for fully utilizing posterior output from the first stage modeling/prediction to make accurate inference on the association between exposure and health in the second stage, derive the full conditional distributions needed for efficient model fitting, detail its connections with existing approaches, and compare its performance through simulation. Our KDE approach is shown to generally have improved performance across several settings and model comparison metrics. Using competing approaches, we investigate the association between lagged daily ambient fine particulate matter levels and stillbirth counts in New Jersey (2011–2015), observing an increase in risk with elevated exposure 3 days prior to delivery. The newly developed methods are available in the R package KDExp.</div><div class="event_time">15:15 &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_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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Dr. Julia Schneider (Universität Zürich)</div><div class="event_title">Birational maps of Severi-Brauer surfaces, with applications to Cremona groups of higher rank <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We describe the group of birational transformations of a non-trivial Severi-Brauer surface over a perfect field, proving that if it contains a point of degree 6, then it is not generated by elements of finite order. We then use this result to study Mori fibre spaces over the field of complex numbers and deduce that the Cremona group of rank at least 4 admits any group (of cardinality at most $|\\mathbb{C}|$) as a quotient. Moreover, we prove that the 3-torsion in the abelianization of the  Cremona group of rank at least 4 is uncountable. This is based on a joint work with J. Blanc and E. Yasinsky.</div><div class="event_time">16:00 &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>';