var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-58"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-56"><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. 5</span>      <span style="float: right; text-align:right; width: 250px;">18.3 - 22.3.2024</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2024</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, March 18      </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"> Jinghao Cao (ETH Zürich)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde/detail/bernoullis-tafelrunde-jinghao-cao-eth-zuerich/">Wave interaction with subwavelength resonators</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />&lt;p><a href="https://dmi.unibas.ch/fileadmin/user_upload/dmi/Studium/Mathematik/Bernoullis_Tafelrunde/_FS24/Jinghao_Cao_2.pdf" target="_blank">abstract</a>&lt;/p></div><div class="event_time">12:15 &bull; Universität Basel, Seminarraum 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"> Dominik  Schmid (University of Bonn)</div><div class="event_title">Biased random walk on dynamical percolation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider a biased random walk on dynamical percolation and discuss the existence and the properties of the linear speed as a function of the bias. In particular, we establish a simple criterion to decide whether the speed is increasing or decreasing for large bias. This talk is based on joint work with Sebastian Andres, Nina Gantert, and Perla Sousi.</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"> Florian Johne (University of Freiburg i. Br.)</div><div class="event_title">Topology and geometry of metrics of positive intermediate curvature <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The notion of m-intermediate curvature interpolates between Ricci curvature and scalar curvature. In this talk we describe extensions of classical results by Bonnet-Myers and Schoen-Yau to the setting of m-intermediate curvature: A non-existence result for metrics of positive m-intermediate curvature on manifolds with topology N^n = T^m x S^{n-m}; a gluing result for manifolds with m-convex boundary; inheritance of spectral positivity along stable minimal hypersurfaces, and estimates for the m-diameter for uniform positive lower bounds. This talk is partially based on joint work with Simon Brendle and Sven Hirsch, and joint work with Aaron Chow and Jingbo Wan.</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">Dr. Wesley Fussner (Czech Academy of Sciences)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Recent Progress on Amalgamation</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Given two mathematical structures A and B with a common substructure, an amalgam of them is another structure C in which A and B embed in such a way that the common substructure is preserved. Amalgamation appears throughout mathematics in many different contexts, and has a number of quite surprising links to seemingly unrelated phenomena. In this talk, we will survey some recent progress on understanding various kinds of amalgamation in the context of ordered algebraic structures. We will also discuss some of the applications of amalgamation to questions in logic, as well as some of the outstanding open problems in the area.</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 19      </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/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Matus Telgarsky (NYU, US)</div><div class="event_title">Feature learning, lower-homogeneity, and normalization layers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The first half of this talk will describe the feature learning problem in deep learning optimization, its statistical consequences, and an approach to proving general theorems with a heavy reliance on normalization layers, which are common to all modern architectures but typically treated as an analytic nuisance. Theorems will cover two settings: concrete results for shallow networks, and abstract template theorems for general architectures. The shallow network results allow for globally maximal margins at the cost of large width and no further assumptions, while the general architecture theorems give convergence rates to KKT points for a new general class of architectures satisfying “partial lower-homogeneity”.The second half will be technical, demonstrating two core proof techniques. The first ingredient, essential to the shallow analysis, is a new mirror descent lemma, strengthening a beautiful idea discovered by Chizat and Bach. The second ingredient is the concept of “partial lower-homogeneity” and its consequences.Joint work with Danny Son; not currently on arXiv, but “coming soon”.</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/annonces/groupes-geometrie">Groupes et Géométrie </a></div><br /><div class="event_speaker"> Ruiwen  Dong  (Saarbrucken)</div><div class="event_title">The Identity Problem in subsemigroups of metabelian groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Algorithmic problems in metabelian groups have been studied as early as the 1950s since the work of Hall. In the 1970s Romanovskii proved decidability of the Group Membership problem (given the generators of a subgroup and a target element, decide whether the target element is in the subgroup) in metabelian groups. However, Semigroup Membership (same as Group Membership, but with sub-semigroups) has been shown to be undecidable in several instances of metabelian groups. In this talk we consider two "intermediate" decision problems: the Identity Problem (deciding if a sub-semigroup contains the neutral element) and the Group Problem (deciding if a sub-semigroup is a group). We reduce them to solving linear equations over the polynomial semiring N[X] and show decidability using a Positivstellensatz-type local-global principle.</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"> Andrey Pilipenko (Kyviv)</div><div class="event_title">On a selection problem for small noise perturbation of unstable dynamical systems  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The well-known Peano existence theorem states that an ordinary differential equation (ODE) with continuous coefficients has a local solution, which, however, may not be unique. On the contrary, an addition of a non-degenerate noise term usually yields the existence of a unique solution to the corresponding stochastic differential equation, even if the drift term is discontinuous. We study the limit of the stochastic equations as the noise intensity converges to zero. This limit can be interpreted as a natural selection of a solution for the initial ODE.The identification of the limit is closely related to a study of the exact growth rate of certain stochastic equations, as well as to an averaging principle.</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"> Christopher Criscitiello (EPFL, CH)</div><div class="event_title">The sensor network localization problem has benign landscape under mild rank relaxation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the sensor network localization problem (also called metric multidimensional scaling): we observe some pairwise distances between n ground-truth points in R^d, and our goal is to recover this cloud of ground-truth points (up to translation and rotation).  The corresponding optimization problem is nonconvex, and we show that it can have spurious local minima.  However, inspired by numerical experiments, we argue that if one relaxes the problem by optimizing over clouds of n points in dimension k greater than d, then all second-order critical points of the problem are global minima.  Specifically, we show this for two settings: (1) for arbitrary ground-truth points, when all pairwise distances are known, and k = O(sqrt{n d}), and: (2) for isotropic random ground-truth points, when most (but not necessarily all) pairwise distances are known, and k = O(d log(n)).  To the best of our knowledge, these are the first landscape results for this nonconvex version of sensor network localization.</div><div class="event_time">14:15 &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_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"> Alexander Thomas (Heidelberg University)</div><div class="event_title">Fock bundles and the Hitchin component <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The study of representations of a fundamental group of a surface into a Lie group is described by the character variety. I will present a new approach, via so-called Fock bundles, to study character varieties. Despite similarities with nonabelian Hodge theory, the crucial difference is that no complex structure is fixed on the surface. Fock bundles are closely related to higher complex structures and Hitchin components. Joint work with Georgios Kydonakis and Charlie Reid. </div><div class="event_time">15:00 &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://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">Prof. Dr. Melanie Rupflin (University of Oxford)</div><div class="event_title">Sharp quantitative results for maps from $S^2$ to $S^2$ of general degree <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />As the energy of any map $v$ from $S^2$ to $S^2$ is at least $4\\pi vert deg(v)\\vert$ with equality if and only if $v$ is a rational map it is natural to ask whether maps with small energy defect $\\de_v=E(v)-4\\pi \\abs{\\deg(v)}$ are necessarily close to a rational map.While such a rigidity statement turns out to be false for maps of general degree, we will prove that any map $v$ with small energy defect is essentially given by a collection of rational maps that describe the behaviour of $v$ at very different scales and that the corresponding distance is controlled by a quantitative estimate of the form $\\text{dist}^2\\leq C \\delta_v(1+\\abs{\\log\\delta_v})$ which is indeed sharp. </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_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">Ana Marija Vego (ETHZ)</div><div class="event_title">What is... an Iwasawa algebra? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />\'\'The Iwasawa algebra is a key object in the study of p-adic L-functions, which are a central topic in number theory. The Iwasawa algebra arises naturally in this context as a tool for understanding the behavior of certain arithmetic invariants, such as Selmer groups and class groups, in towers of number fields. It provides a framework for studying these invariants in a unified way over all the levels of the tower. This allows us to investigate the arithmetic properties of number fields and their associated objects, particularly in the context of p-adic L-functions and Galois representations. It has applications in various areas of number theory, including the study of special values of L-functions, the Birch and Swinnerton-Dyer conjecture, and the structure of class groups of number fields. In this talk we will introduce Iwasawa algebras and give some basic properties. We\'ll then explore how these algebras are used in constructing Euler systems and obtaining p-adic L-functions. If time allows, we\'ll also touch on the main conjecture of Iwasawa theory.</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">Prof. Dr. Bruno Colbois (Uni Neuchâtel)</div><div class="event_title">Isoperimetric inequalities and spectrum of the Laplacian <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 relate some fairly classical results concerning isoperimetric inequalities to results concerning the spectrum of the Laplacian in Euclidean domains. In the last part of the talk, I will present some new results. Throughout the talk, I will also present some open questions that are fairly simple to formulate (but perhaps not to solve).</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, March 20      </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://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Dr. Yi Pan (Institute of Science and Technology Austria)</div><div class="event_title">Reducibility of quasi-periodic cocycles valued in symplectic groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Reducibility of quasi-periodic cocyles valued in symplectic groups is related to the spectrum of discrete Schrödinger operators on strips. We will talk about a global reducibility result: given one parameter family of such cocycles, for almost every parameter, either the maximal Lyapunov exponent is positive, or the cocycle is almost conjugate to some precise model. The techniques include Kotani thoery, KAM theory and in particular study of hyperbolicity of renormalization operator. This is a joint work with Artur Avila and Raphaël Krikorian.</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">Dr. Chiara Meroni (ETH-ITS)</div><div class="event_title">The algebra of convex hulls <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Convex hulls and their boundaries are complicated but relevant objects in convex geometry and optimization. However, there is an algebraic technique to study the convex hull of a real variety. The goal is to understand which varieties contribute to the boundary. I will explain this general method and then focus on the case of smooth surfaces in four-dimensional space, in particular Veronese, Del Pezzo, and Bordiga surfaces.</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_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"> Norbert J. Mauser (WPI and MMM c/o Univ. Wien)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-norbert-j-mauser-wpi-and-mmm-c-o-univ-wien/">Model hierarchies in semiclassical semi-relativistic quantum physics: From Dirac-Maxwell to Euler-Poisson</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />&lt;p>The Pauli-Poisswell equation models fast moving charges in&lt;/p>&lt;p>semiclassical semi-relativistic quantum dynamics. It is at the&lt;/p>&lt;p>center of a hierarchy of models from the Dirac-Maxwell equation to&lt;/p>&lt;p>the Euler-Poisson equation that are linked by asymptotic analysis of&lt;/p>&lt;p>small parameters such as Planck constant or inverse speed of light.&lt;/p>&lt;p>We discuss the models and their application in plasma and&lt;/p>&lt;p>accelerator physics as well as the many mathematical problems they&lt;/p>&lt;p>pose.&lt;/p></div><div class="event_time">14:15 &bull; Universität Basel</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">PD Dr. Menny Akka Ginosar (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">Seifert surfaces, planes in four space, and Gauss composition <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 present results from a recent joint work with Peter Feller, Alison Beth Miller and Andreas Wieser (https://arxiv.org/abs/2311.17746).I will first present a geometric approach to the classical Gauss composition of binary quadratic forms. The new method is based on a parameterisation of two-dimensional subspaces of the space of 2x2 matrices and provides an easy to remember way to compute the Gauss composition. This approach naturally leads to a robust construction of pairs of Seifert surfaces for the same knot that are non-isotopic in the 4-ball. It also provides a complete characterisation of the Seifert forms of such disjoint Seifert surfaces. These topological results will be discussed in the second part of the talk. No background in number theory or knot theory will be assumed.</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/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Dr. Jean-Jil Duchamps (Université de Franche-Comté / Besançon)</div><div class="event_title">Local weak convergence for a general stochastic SIR model <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study an epidemiological model where infections arise in a population according to a general, non-Markovian SIR-like model with a time-dependent contact rate. We make few assumptions, only requiring that the number of potential infections generated by an individual has finite expectation on bounded time intervals. This model can be viewed as a general Crump-Mode-Jagers model with interactions, and we study the local weak convergence of its infection graph, which yields (1) a functional law of large numbers for our SIR process, and (2) the identification of a "contact-tracing Markov process" that traces back the chain of infection leading to a typical individual.This is joint work with Félix Foutel-Rodier and Emmanuel Schertzer.</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, March 21      </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_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"> Matus Telgarsky</div><div class="event_title">Feature learning, lower-homogeneity, and normalization layers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The first half of this talk will describe the feature learning problem in deep learning optimization, its statistical consequences, and an approach to proving general theorems with a heavy reliance on normalization layers, which are common to all modern architectures but typically treated as an analytic nuisance.  Theorems will cover two settings: concrete results for shallow networks, and abstract template theorems for general architectures. The shallow network results allow for globally maximal margins at the cost of large width and no further assumptions, while the general architecture theorems give convergence rates to KKT points for a new general class of architectures satisfying "partial lower-homogeneity".The second half will be technical, demonstrating two core proof techniques. The first ingredient, essential to the shallow analysis, is a new mirror descent lemma, strengthening a beautiful idea discovered by Chizat and Bach. The second ingredient is the concept of "partial lower-homogeneity" and its consequences.Joint work with Danny Son; not currently on arXiv, but "coming soon".</div><div class="event_time">11:15 &bull; EPF Lausanne, GA 3 21</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Mathias Schuett</div><div class="event_title">Real multiplication for K3 surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Real multiplication (RM) not only occurs on abelian varieties (in terms of endomorphisms), but also on K3 surfaces and other Calabi-Yau varieties via Hodge structures. Contrary to the CM case, RM remains rather mysterious, largely evading explicit examples. I will report on joint work with Eva Bayer and Bert van Geemen which engineers both explicit new constructions of K3 surfaces with RM (and CM) and abstract existence results. </div><div class="event_time">14:15 &bull; EPF Lausanne, Bernoulli center, GA 3 34</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/~palmeran/topsem.html">Séminaire de Topologie et Géométrie </a></div><br /><div class="event_speaker"> Mikami  Hirasawa  (Nagoya Institute of Technology)</div><div class="event_title">The equivariant genera of marked strongly invertible knots associated with $2$-bridge knots <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A marked strongly invertible knot is a triple $(K,h,\\delta)$ of a knot $K$ in $S^3$, a strong inversion $h$ of $K$, and a subarc $\\delta \\subset \\Fix(h)\\cong S^1$ bounded by $\\Fix(h)\\cap K\\cong S^0$. An invariant Seifert surface for $(K,h,\\delta)$ is an $h$ invariant Seifert surface for $K$ that intersects $\\Fix(h)$ in the arc $\\delta$. In this paper, we completely determine the equivariant genus (the minimum of the genera of invariant Seifert surfaces for $(K,h,\\delta)$) of every marked strongly invertible knot $(K,h,\\delta)$ with $K$ a $2$-bridge knot. We concretely construct invariant Seifert surfaces on minimal equivariant genera.This is a joint work with Makoto Sakuma and Ryota Hiura.</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://stat.ethz.ch/events/research_seminar">Research Seminar in Statistics</a></div><br /><div class="event_speaker"> Bryon Aragam (The University of Chicago Booth School of Business)</div><div class="event_title">Research Seminar on Statistics - FDS Seminar joint talk: Statistical aspects of nonparametric latent variable models and causal representation learning <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />One of the key paradigm shifts in statistical machine learning over the past decade has been the transition from handcrafted features to automated, data-driven representation learning. A crucial step in this pipeline is to identify latent representations from observational data along with their causal structure. In many applications, the causal variables are not directly observed, and must be learned from data, often using flexible, nonparametric models such as deep neural networks. These settings present new statistical and computational challenges that will be focus of this talk. We will re-visit the statistical foundations of nonparametric latent variable models as a lens into the problem of causal representation learning. We discuss our recent work on developing methods for identifying and learning causal representations from data with rigourous guarantees, and discuss how even basic statistical properties are surprisingly subtle. Along the way, we will explore the connections between causal graphical models, deep generative models, and nonparametric mixture models, and how these connections lead to a useful new theory for causal representation learning.</div><div class="event_time">16:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room D 1.2</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/sfs/news-and-events/data-science-seminar">ETH-FDS seminar </a></div><br /><div class="event_speaker"> Bryon Aragam (The University of Chicago Booth School of Business)</div><div class="event_title">Research Seminar on Statistics - FDS Seminar joint talk: Statistical aspects of nonparametric latent variable models and causal representation learning <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />One of the key paradigm shifts in statistical machine learning over the past decade has been the transition from handcrafted features to automated, data-driven representation learning. A crucial step in this pipeline is to identify latent representations from observational data along with their causal structure. In many applications, the causal variables are not directly observed, and must be learned from data, often using flexible, nonparametric models such as deep neural networks. These settings present new statistical and computational challenges that will be focus of this talk. We will re-visit the statistical foundations of nonparametric latent variable models as a lens into the problem of causal representation learning. We discuss our recent work on developing methods for identifying and learning causal representations from data with rigourous guarantees, and discuss how even basic statistical properties are surprisingly subtle. Along the way, we will explore the connections between causal graphical models, deep generative models, and nonparametric mixture models, and how these connections lead to a useful new theory for causal representation learning.</div><div class="event_time">16:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room D 1.2</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, March 22      </div>      <div class="day_content">        <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"> Anuj Kumar (Berkeley)</div><div class="event_title">Nonunique solutions of the transport equation for Sobolev vector fields <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> This talk is based on recent work jointly with E. Bruè and M. Colombo. We construct nonuniquesolutions of the continuity equation in the class L^\\infty in time and L^rin space. We achieve this by introducing two novel ideas: (1) In the construction, we interweave the scaled copies ofthe vector field itself. (2) Asynchronous translation of cubes, which makes the constructionheterogeneous in space. These new ideas allow us to prove nonuniqueness in the range ofexponents 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; EPF Lausanne</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>';