var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-191"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-189"><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. 6</span>      <span style="float: right; text-align:right; width: 250px;">27.3 - 31.3.2023</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2023</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, March 27      </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"> Marcello Negri (Universität Basel)</div><div class="event_title">Normalizing flows for density estimation and sampling <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Longstanding goals of statistics and machine learning have been to model a prob-ability distribution from its samples and, viceversa, to learn how to sample from agiven distribution. Normalizing ows are powerful machine learning models that al-low to perform both tasks in an e&#8192;cient and exact way. This is achieved by de&#8192;ningan expressive probability distributions by transforming a simple base distributionthrough a series of bijective transformations, which give a great exibility in thechoice of model design. In this talk we aim to review normalizing ows in the lightof probabilistic modeling and inference while analyzing the fundamental principles,expressive power, computational trade-o&#8192;s, and di&#8192;erent architectures.</div><div class="event_time">12:15 &bull; Universität Basel, Spiegelgasse 5, SR 05.002</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/mat770.1">Oberseminar: Algebraische Geometrie</a></div><br /><div class="event_speaker">Dr. Mauro Porta (Université de Strasbourg)</div><div class="event_title">Non-archimedean Gromov-Witten invariants and Mirror symmetry <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Mirror symmetry is a subject at the crossroad of symplectic geometry, complex analytic geometry and mathematical physics. Informally, it is a conjectural duality between Calabi-Yau varieties: given such a variety X (or, rather, a family of such objects), there should be a second variety (or family) Y, called the "mirror" of X. The pair (X,Y) should be characterised by the fact that symplectic invariants of X should correspond to holomorphic invariants of Y. Nevertheless, the construction of Y out of X stays an open major problem of the theory: it has been solved in countless many examples, but not in general. In 2006 Kontsevich and Soibelman proposed an attack strategy based on non-archimedean geometry. In this exposé I will survey the history of this program, focusing on the key moments and the recent advances dues to S. Keel, J. Nicaise, C. Xu, T. Y. Yu and myself.</div><div class="event_time">13:15 &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://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Prof. Dr. Alex Eskin (University of Chicago)</div><div class="event_title">A homogeneous dynamics approach to Gibbs u-states <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Gibbs u-states are a distinguished class of measures invariant by a partially hyperbolic diffeomorphism of a manifold. These measures and the related SRB measures have been studied extensively in various situations. There are some preliminary indications that homogeneous dynamics methods are relevant to this circle of questions. I will try to sketch this connection.</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_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">Analysis Seminar</a></div><br /><div class="event_speaker"> Dorin Bucur (Université de Savoie)</div><div class="event_title">Maximization of Neumann Eigenvalues <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We discuss the maximization of  the $k$-th eigenvalue of the Laplace operator with Neumann boundary conditions among domains of ${\\mathbb R}^N$ with prescribed measure. We relax the problem to the class of (possibly degenerate) densities in ${\\mathbb R}^N$ with prescribed mass and prove the existence of an optimal density. For $k=1,2$ the two problems are equivalent and the maximizers are known to be one and two equal balls, respectively. For $k \\ge 3$ this question remains open, except in one dimension of the space where we prove that the maximal densities correspond to a union of $k$ equal segments. This result provides sharp upper bounds for Sturm-Liouville eigenvalues and proves the validity of the P\\\'olya conjecture in the class of  densities in $\\mathbb R$.<br>Based on the relaxed formulation, we provide numerical approximations of optimal densities for $k=1, \\dots, 8$ in $\\R^2$. Time remaining, I will point out some peculiar behaviour of the same problem on the sphere. This are joint works with A. Henrot, E. Martinet, M. Nahon and E. Oudet.</div><div class="event_time">14:00 &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://math.ethz.ch/s/symplectic-geometry-seminar">Symplectic Geometry Seminar</a></div><br /><div class="event_speaker"> Yusuke Kawamoto (ETH Zürich)</div><div class="event_title">Isolated hypersurface singularities, spectral invariants, and quantum cohomology <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We discuss the relation between hypersurface singularities (e.g.ADE, $\\widetilde{E}_{6},\\widetilde{E}_{7},\\widetilde{E}_{8}$, etc) andspectral invariants, which are symplectic invariants coming from Floer theory.</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_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/tggroup/doku.php?id=fables">Séminaire "Fables Géométriques" </a></div><br /><div class="event_speaker"> Sebastian Haney (Columbia University)</div><div class="event_title">Mirror Lagrangians to lines in P^3 <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We discuss work in progress in which we construct, for any tropical curve in R^n with vertices of valence at most 4, a Lagrangian submanifold of (C^*)^n whose moment map projection is a tropical amoeba. These Lagrangians will have singular points modeled on the Harvey-Lawson cone over a 2-torus. We also consider a certain 4-valent tropical curve in R^3, for which we can modify the singular Lagrangian lift to obtain a cleanly immersed Lagrangian. The objects of the wrapped Fukaya category supported on this Lagrangian correspond, under mirror symmetry, to lines in CP^3. If time permits, we will explain how to use functors induced by Lagrangian correspondences to see this mirror relation. </div><div class="event_time">16:00 &bull; Université de Genève, Conseil Général 7-9, Room 6-13</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">Dr. Elif Saçikara (Aalto University)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">q-Analoues of Matroids</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Matroids are defined as a combinatorial abstraction of several objects such as linearly independent vectors or graphs. On the other hand, in combinatorics, a q-analog of a discrete structure is defined by replacing finite sets with finite dimensional vector spaces.In this talk, we first define a matroid with certain equivalent axiomatic definitions, which are called cryptomorphism, by supporting them with trivial examples. Then we discuss their q-analogs by comparing differences and similarities with the classical case. Finally, as a construction and an application of a q-matroid, we mention their relation with a q-analog of other combinatorial objects called designs, and state some open questions. This work is a part of the research project supported by Women in Numbers - Europe and of a master studies of Martin Bergamin at the UZH.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Lecture Room B6</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, March 28      </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"> Karoly Böröczky (Alfréd Rényi Institute of Mathematics)</div><div class="event_title">The Isoperimetric inequality, the Brunn-Minkowski theory, and the Lp Minkowski problem</div><div class="event_time">10:15 &bull; Zoom</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.unine.ch/math/home/colloques_et_seminaires/seminaires-de-linstitut.html">Séminaire Groupes et Géométrie </a></div><br /><div class="event_speaker"> Marialaura Noce (Università Salento)</div><div class="event_title">Lower central series of some groups acting on rooted trees <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A rapidly developing area of group theory studies the properties of branch groups, a special kind of groups acting on rooted trees. An important motivation for studying branch groups comes from the remarkable properties that some of these groups can possess, like intermediate growth, amenability, the congruence subgroup property, or providing a negative answer to the General Burnside Problem.  Among other properties, some research in the last decade has been done regarding the lower central series of subgroups of the group of automorphisms acting on rooted trees. <br>In this talk, we first survey some known results about the lower central series in first Grigorchuk group, the Gupta-Sidki 3-group, and the Fabrykowski-Gupta group, and then we present new results and some open problems.</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.unil.ch/dsa/en/home/menuinst/seminaires--evenements/research-seminars.html">Talks in Actuarial Mathematics </a></div><br /><div class="event_speaker"> Mogens Steffensen (University of Copenhagen)</div><div class="event_title">Optimal consumption, investment, and insurance under state-dependent risk aversion <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We formalize a consumption-investment-insurance problem with the distinction of a state-dependent relative risk aversion. The state-dependence refers to the state of the finite state Markov chain that also formalizes insurable risks such as health and lifetime uncertainty. We derive and analyze the implicit solution to the problem, compare it with special cases in the literature, and illustrate the range of results in a disability model where the relative risk aversion is preserved, decreases, or increases upon disability. We also discuss whether the approach is appropriate to deal with uncertainty in relative risk aversion and consider some alternative ideas.</div><div class="event_time">11:00 &bull; EPF Lausanne, UniL campus, Extranef 125</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/research_seminar">Research Seminar in Statistics</a></div><br /><div class="event_speaker"> Boaz Nadler (The Weizmann Institute of Science, Israel)</div><div class="event_title"> The Trimmed Lasso: Sparse Recovery Guarantees And Practical Optimization <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Consider the sparse approximation or best subset selection problem: Given a vector y and a matrix A, find a k-sparse vector x that minimizes the residual ||Ax-y||. This sparse linear regression problem, and related variants, plays a key role in high dimensional statistics, compressed sensing, and more. In this talk we focus on the trimmed lasso penalty, defined as the L_1 norm of x minus the L_1 norm of its top k entries in absolute value. We advocate using this penalty by deriving sparse recovery guarantees for it, and by presenting a practical approach to optimize it. Our computational approach is based on the generalized soft-min penalty, a smooth surrogate that takes into account all possible k-sparse patterns. We derive a polynomial time algorithm to compute it, which in turn yields a novel method for the best subset selection problem. Numerical simulations illustrate its competitive performance compared to current state of the art.</div><div class="event_time">13:15 &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_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 (University of Bergen)</div><div class="event_title">The aromatic bicomplex for the study of volume-preserving integrators <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />While B-series are used to represent the Taylor expansion of the solution of an ODE, aromatic B-series appear when computing the divergence of such a Taylor expansion. In this talk, we define aromatic forms (in the spirit of differential forms), we extend the divergence operator on aromatic forms, and we introduce the aromatic bicomplex, in the spirit of the variational bicomplex in differential geometry. We prove the exactness of this bicomplex with the help of the Euler and the homotopy operators. We will describe the far-reaching implications of the exactness of the aromatic bicomplex in the study of volume preservation.</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_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/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker"> Tatiana Brailovskaya (Princeton University, Princeton, USA)</div><div class="event_title">Universality and matrix concentration inequalities <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Random matrices frequently appear in many different fields — physics, computer science, applied and pure mathematics. Oftentimes the random matrix of interest will have non-trivial structure — entries that are dependent and have potentially different means and variances (e.g. sparse Wigner matrices, matrices corresponding to adjacencies of random graphs, sample covariance matrices). However, current understanding of such complex random matrices remains lacking. In this talk, I will discuss recent results concerning the spectrum of sums of independent random matrices with a.s. bounded operator norms. In particular, I will demonstrate that under some fairly general conditions, such sums will exhibit the following universality phenomenon — their spectrum will lie close to that of a Gaussian random matrix with the same mean and covariance. No prior background in random matrix theory is required — basic knowledge of probability and linear algebra are sufficient. (joint with Ramon van Handel)Pre-print link:https://web.math.princeton.edu/~rvan/tuniv220113.pdf</div><div class="event_time">14:45 &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://www.epfl.ch/labs/stoan/probability-stochastic-analysis-seminar/">Probability (and Stochastic Analysis) Seminar </a></div><br /><div class="event_speaker"> Christopher Garban (Université de Lyon & Genève)</div><div class="event_title">Title T.B.A.</div><div class="event_time">15:00 &bull; EPF Lausanne, Salle CM 0 11</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"> Andras Szenes (Université de Genève)</div><div class="event_title">Intersection cohomology of the moduli spaces of stable bundles <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Intersection cohomology is a topological notion adapted to the description of singular topological spaces. The Decomposition Theorem for maps of algebraic varieties is a key tool in the subject, generalizing the Leray-Hirsch theorem.The study of the intersection cohomology of the moduli spaces of semistable bundles on Riemann surfaces began in the 80’s with the works of Frances Kirwan. Motivated by the work of Mozgovoy and Reineke, in joint work with Camilla Felisetti and Olga Trapeznikova, we give a complete description of these structures via a detailed analysis of the Decomposition Theorem applied to a certain map. We also give a new formula for the intersection Betti numbers of these moduli spaces, which has a clear geometric meaning. In these talk, I will give an introduction to the subject, and describe our results.</div><div class="event_time">15:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</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://math.ethz.ch/s/zurich-colloquium-in-mathematics">Zurich Colloquium in Mathematics</a></div><br /><div class="event_speaker"> Hannah Markwig (University of Tübingen)</div><div class="event_title">Counting bitangents of quartic curves - arithmetic, real, tropical <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We showcase tropical geometry as a tool for geometric counting problems. A nice feature of tropical geometry is that many techniques can be applied simultaneously over various ground fields, e.g. for complex or real counting problems. Our prime example will be the count of bitangent liens to a smooth plane quartic.Already Plücker knew that a smooth complex plane quartic curve has exactly 28 bitangents. Bitangents of quartic curves are related to a variety of mathematical problems. They appear in one of Arnold\'s trinities, together with lines in a cubic surface and 120 tritangent planes of a sextic space curve. In this talk, we review known results about counts of bitangents under variation of the ground field. Special focus will be on counting in the tropical world, and its relations to real and arithmetic counts. We end with new results concerning the arithmetic multiplicity of tropical bitangent classes, based on joint work with Sam Payne and Kris Shaw.</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_ne"><a class="external" href="https://unine.ch">Université de Neuchâtel</a></div><div class="event_type"><a class="external" href="http://www.unine.ch/math/home/colloques_et_seminaires/les-colloques-du-mardi.html">Colloque du Mardi </a></div><br /><div class="event_speaker"> Martin Leguil (Université de Picardie, Amiens)</div><div class="event_title">Some topics of smooth ergodic theory <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 of ergodic theory is to describe the statistical behavior of most orbits of a given dynamical system. For "chaotic systems" (more precisely, those exhibiting some form of hyperbolicity), certain dynamical foliations (stable/unstable foliations) prove to be very useful in the study of statistical properties of such systems. In this talk I will recall basic notions of these foliations, and how these geometric objects interact with some invariant measures of particular interest, the so-called SRB measures, which describe the statistical behavior of a "large" set of points. I will also mention the special case of conservative systems, where a famous argument due to Hopf shows that a certain property of these foliations, called accessibility, can be employed to show that the system is ergodic. For partially hyperbolic systems, I will introduce a certain class of measures, the so-called u-Gibbs measures, explain how such measures can be constructed, and how they are related to the SRB measures. </div><div class="event_time">17:00 &bull; Université de Neuchâtel, Rue Emile Argand 11, Auditoire B013</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, March 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"> Shahar Mendelson (The Australian National University)</div><div class="event_title">Probabilistic methods in Analysis</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_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">Prof. Dr. Stefan Wenger (Unversité de Fribourg)</div><div class="event_title">Geometric and analytic structures on spaces homeo- morphic to a manifold <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We explore geometric and analytic aspects of metric spaces homeomorphic to a topological manifold, sometimes called metric manifolds. Such spaces are prominently studied in the field of analysis on metric spaces for example in connection with parametrization problems and they also appear naturally in geometric group theory as boundaries of some hyperbolic groups. Only assuming linear local contractibility and finite Hausdorff measure, we show that one can make sense of "integration of differential forms" on such spaces and obtain some kind of Stokes’ theorem as well as an analytic analog of the fundamental class. This then allows us to use modern techniques from minimal surface theory to establish (relative) isoperimetric inequalities on metric manifolds. As an application we can provide a conceptually simple proof of a deep theorem of Semmes about the validity of Poincaré inequalities in metric manifolds. Such inequalities form the basis for developing a robust theory of first order calculus in the setting of metric spaces. <br>Based on joint work with G. Basso and D. Marti.</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://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Renzo Cavalieri (Colorado State University)</div><div class="event_title">Tropical contributions to enumerative geometry of target dimension 1, Part II <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This cycle of talks wants to highlight how ideas from tropical geometry have contributed not only to the solution, but also to the development of enumerative geometric problems regarding moduli spaces of curves, and maps from curves to curves. We will spend a little of time reviewing the origins of this story, i.e. the development of tropical Hurwitz numbers as combinatorial analogues for the classical Hurwitz numbers. We will discuss a more recent interpretation that views tropical Hurwitz numbers as the natural computation for the intersection number of the double ramification cycle with an element of the log Chow ring of the moduli space of curves (called in this case the branch polynomial, as it is presented as a piecewise polynomial function on the moduli spaces of tropical curves) which is determined by the tropical moduli space of covers of the projective line. We will see that from the tropical perspective analogous piecewise polynomial functions may be associated to $k$-DR cycles (cycles arising from spaces of twisted pluri-differentials), thus giving rise to $k$-analogues of Hurwitz numbers (called leaky Hurwitz numbers) that enjoy many of the algebro-combinatorial properties of Hurwitz numbers - such as piecewise polynomiality and wall crossings.We will present some work in progress which intends to incorporate descendants into these pictures. Tropical algorithms are developed that give rise to some intruiguingly simple formulas in the case when one point is fully ramified. The material presented is based on many years of joint work with several people, including Paul Johnson, Hannah Markwig, Dhruv Ranganathan and Johannes Schmitt.</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_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">Prof. Dr. Michele Wigger (Telecom Paris, LTCI)</div><div class="event_title">Lectures on Information Theory - Part 3 <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Strong typicality &lt;BR> &lt;BR> (**This eSeminar will take place over Zoom, using the same meeting details as previous seminars. If you do not have meeting details, please contact zita.fiquelideabreu@math.uzh.ch **)</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"> Alina Vdovina (Newcastle University)</div><div class="event_title">Higher-dimensional automata, Ramanujan shifts and buildings <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We suggest a new definition of higher-dimensional automatamotivated by cocompact quotients of buildings. We construct infinite series of such automata and produce very explicit constructions ofRamanujan higher-dimensional graphs.</div><div class="event_time">15:45 &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">Prof. Dr. Michele Wigger (Telecom Paris, LTCI)</div><div class="event_title">Lectures on Information Theory - Part 4 <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Shanonn\'s lossless source coding theorem; Stein\'s Lemma for hypothesis testing &lt;BR> &lt;BR> (**This eSeminar will take place over Zoom, using the same meeting details as previous seminars. If you do not have meeting details, please contact zita.fiquelideabreu@math.uzh.ch **)</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://uzh.ch">Universit&auml;t 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. Christian Lubich (Universität Tübingen)</div><div class="event_title">Time-dependent scattering from thin layers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The scattering of electromagnetic waves from obstacles with wave-material interaction in thin layers on the surface is described by generalized impedance boundary conditions, which provide effective approximate models.In particular, this includes a thin coating around a perfect conductor and the skin effect of a highly conducting material. The approach taken here is to derive, analyse and discretize a system of time-dependent boundary integral equations that determines the tangential traces of the scattered electric and magnetic fields. The fields are then evaluated in theexterior domain by a known representation formula, which uses the time-dependent potential operators of Maxwell’s equations. The time-dependent boundary integral equation is discretized with Runge-Kutta based convolution quadrature in time and Raviart–Thomas boundary elements in space.The well-posedness analysis of the boundary integral equation as well as the error analysis of the numerical methods relies on frequency-explicit bounds in the Laplace domain. These are then transferred to the time domain and combined with known approximation estimates of the numerical methods.The talk is based on joint work with Balázs Kovács and Jörg Nick.</div><div class="event_time">16:30 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 35/36</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, March 30      </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"> Brita Nucinkis (Royal Holloway, University of London)</div><div class="event_title">Cohomological methods in group theory</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_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"> Alessio Cela (ETH Zürich)</div><div class="event_title">Fixed-domain curve counts for blow-ups of projective space <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 explain some new results about the problem of counting pointed curves of fixed complex structure in blow-ups of projective space at general points. The geometric and the virtual Gromov-Witten counts in genus 0 and in higher genus for large anti-canonical degree curve classes agree in the Fano (and some $(-K)$-nef) examples, but not in general. For toric blow-ups, geometric counts can be expressed in terms of integrals on products of Jacobians and symmetric products of the domain curves, and evaluated explicitly in genus 0 and in the case of Bl_q(P^r), obtaining very simple closed formulas.</div><div class="event_time">13:15 &bull; EPF Lausanne, Salle MA A3 30</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"> Christine Lescop (CNRS, Université Grenoble Alpes)</div><div class="event_title">Un invariant sympathique des noeuds de genre un <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Dans cet exposé élémentaire, on introduira un invariant topologique w facile à calculer pour les noeuds qui bordent des surfaces compactes orientables de genre un (dans l\'espace ambiant ou dans une sphère d\'homologie de dimension trois). La démonstration de l\'invariance de w repose sur l\'étude d\'un invariant de telles surfaces de Seifert de genre un défini à partir du revêtement abélien libre maximal de leurs complémentaires.</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://www.eth-its.ethz.ch/activities/its-science-colloquium.html">ITS Science Colloquium</a></div><br /><div class="event_speaker"> Alex Eskin (University of Chicago and ETH-&#8203;ITS)</div><div class="event_title"><a class="external" href="https://eth-its.ethz.ch/activities/its-science-colloquium.html">Polygonal Billiards and Dynamics on Moduli Spaces</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Billiards in polygons can exhibit bizarre behavior, some of which can be explained by deep connections to several seemingly unrelated branches of mathematics. These include algebraic geometry, Teichmuller theory and ergodic theory on homogeneous spaces. The talk will be an introduction to these ideas, aimed at a general mathematical audience. </div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room E 5</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://www.math.uzh.ch/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Angeliki Menegaki (IHES, Université Paris-Saclay)</div><div class="event_title">CANCELLED: Quantitative framework for hydrodynamic limits <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We will present a new quantitative approach to the problem of proving hydrodynamic limits from microscopic stochastic particle systems, namely the zero-range and the Ginzburg-Landau process with Kawasaki dynamics, to macroscopic partial differential equations. Our method combines a modulated Wasserstein-distance estimate comparing the law of the stochastic process to the local Gibbs measure, together with stability estimates a la Kruzhkov in weak distance and consistency estimates exploiting the regularity of the limit solution. It is simplified as it avoids the use of the block estimates. This is a joint work with Daniel Marahrens and Clément Mouhot (University of Cambridge).</div><div class="event_time">16:00 &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_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://www.ntwebseminar.org/">Number Theory Web Seminar</a></div><br /><div class="event_speaker"> Ziyang Gao (Leibniz Universität Hannover)</div><div class="event_title">Sparsity of rational and algebraic points <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It is a fundamental question in mathematics to find rational solutions to a given system of polynomials, and in modern language this question translates into finding rational points in algebraic varieties. This question is already very deep for algebraic curves defined over Q. An intrinsic natural number associated with the curve, called its genus, plays an important role in studying the rational points on the curve. In 1983, Faltings proved the famous Mordell Conjecture (proposed in 1922), which asserts that any curve of genus at least 2 has only finitely many rational points. Thus the problem for curves of genus at least 2 can be divided into several grades: finiteness, bound, uniform bound, effectiveness. An answer to each grade requires a better understanding of the distribution of the rational points.<br>In my talk, I will explain the historical and recent developments of this problem according to the different grades.<br>Another important topic on studying points on curves is the torsion packets. This topic goes beyond rational points. I will also discuss briefly about it in my talk.<br>If time permits, I will mention the corresponding result in high dimensions.</div><div class="event_time">17:00 &bull; <a class="external" href="https://www.ntwebseminar.org/">Universität Basel, online Seminar</a></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. Nabil Kazi-Tani (Université de Lorraine)</div><div class="event_title">The role of correlation in diffusion control ranking games <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 study Nash equilibria in two player continuous time stochastic differential games with diffusion control, and where the Brownian motions driving the state processes are correlated. We consider zero-sum ranking games, in the sense that the criteria to optimize only depends on the difference of the two players\' state processes. We explicitly compute the players\' equilibrium strategies, depending on the correlation of the Brownian motions driving the two state equations: in particular, if the correlation coefficient is smaller than some explicit threshold, then the equilibrium strategies consist of strong controls, whereas if the correlation exceeds the threshold, then the equilibrium controls are mixed strategies. To characterize these equilibria, we rely on a relaxed formulation of the game based on solutions to martingale problems, allowing the players to randomize their actions. The talk is based on a joint work with Stefan Ankirchner (University of Jena) and Julian Wendt (University of Jena).</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 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/alice-roth-lectures.html">Alice Roth Lectures</a></div><br /><div class="event_speaker"> Gigliola Staffilani (Massachusetts Institute of Technology)</div><div class="event_title">Waves: building blocks in nature and in mathematics</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">        Friday, March 31      </div>      <div class="day_content">        <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.imsv.unibe.ch/research/talks/colloquia/index_eng.html">Colloquia on Probability and Statistics </a></div><br /><div class="event_speaker">Prof. Dr. Blaise Melly (Universität Bern)</div><div class="event_title"><a class="external" href="https://www.imsv.unibe.ch/research/talks/colloquia/index_eng.html">Minimum Distance Estimation of Panel Quantile Models (with Martina Pons)</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We propose a minimum distance estimation approach to quantile panel data models where the unit effects may be correlated with the covariates. The estimation method is computationally straightforward to implement and fast. We first compute a quantile regression within each unit and then apply GMM to the fitted values from the first stage. The suggested estimators apply (i) to grouped data, where we observe data at the individual level, but the treatment varies at the group level, and (ii) to classical panel data, where we follow the same units over time. Depending on the variables assumed to be exogenous, this approach provides quantile analogs of the classical least squares panel data estimators such as the fixed effects, random effects, between, and Hausman-Taylor estimators. We provide a more precise estimator for grouped (instrumental) quantile regression than the existing ones. We establish the asymptotic properties of our estimator when the number of units and observations per unit jointly diverge to infinity. We suggest an inference procedure that automatically adapts to the (potentially) unknown rate of convergence of the estimators. Monte Carlo simulations show that our estimator and inference procedure also perform well in finite samples when the number of observations per unit is small. In an empirical application, we find that the introduction of the food stamp program increased the birth weights only at the bottom of the distribution.</div><div class="event_time">15:00 &bull; Universität Bern, IMSV, Alpeneggstrasse 22, 3012 Bern, Hörraum -203</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"> Anna Calissano (INRIA)</div><div class="event_title">Populations of Unlabelled Networks: Graph Space Geometry and Generalized Geodesic Regression Model <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Sets of graphs (or networks) arise in many different fields, from medicine to finance, from sport to the social sciences. The analysis of unlabelled graphs or networks is far from trivial due to the highly non-Euclidean nature of such data. We describe Graph Space as a possible geometric embedding for a set of unlabelled graphs, i.e. graphs with no node correspondence across observations. Graph Space is a quotient space, but it is not a manifold, requiring the definition of statistical methods beyond the tangent space approach.<br>We introduce the Align All and Compute algorithm and modify it for both estimating generalised geodesic principal components and generalised geodesic regression models, showing how to interpolate between unlabelled graphs. We demonstrate the flexibility of the framework on both simulated data, public transport system data and Fifa 2018 player passing network data.</div><div class="event_time">15:15 &bull; EPF Lausanne, Salle GA 3 21 </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>';