var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-4"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-2"><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;">24.3 - 28.3.2025</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2025</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, March 24      </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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> David  Persson</div><div class="event_title"> Near-optimal hierarchical matrix approximation from matrix-vector products <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We describe a randomized algorithm for producing a near-optimalhierarchical off-diagonal low-rank (HODLR) approximation to an n x nmatrix A, accessible only through matrix-vector products with A and itstranspose. We prove that, for the rank-k HODLR approximation problem,our method obtains a (1+eps)-optimal approximation with O(klog^4(n)/eps^3) matrix-vector products. Apart from matrix-vectorproducts, the additional computational cost of our method is just O(npoly(log(n), k)). We complement the upper bound with a lower bound,which shows that any matrix-vector query algorithm requires at leastOmega(k log(n) + k/eps) queries to obtain a (1+eps)-optimal approximation.Our algorithm can be viewed as a robust version of widely used"peeling\'\' methods for recovering HODLR matrices and is, to the best ofour knowledge, the first matrix-vector query algorithm to enjoytheoretical worst-case guarantees for approximation by any hierarchicalmatrix class. To control the propagation of error between levels ofhierarchical approximation, we introduce a new perturbation bound forlow-rank approximation, which shows that the widely used GeneralizedNyström method enjoys inherent stability when implemented with noisymatrix-vector products. We also introduce a novel randomly perforatedmatrix sketching method to further control the error in the peelingalgorithm.</div><div class="event_time">12:15 &bull; EPF Lausanne, INJ114</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"> Laurent Côté (University of Bonn)</div><div class="event_title"> Fukaya categories of conical symplectic resolutions <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Conical symplectic resolutions are a rather loosely definedclass of hyperkähler varieties arising from canonical constructions inrepresentation theory. Important examples include hypertoric varieties,Nakajima quiver varieties and Hitchin spaces. I will talk about Fukayacategories of conical symplectic resolutions. These are very rich objects,and they also turn out to be related to geometric representation theory.I will try to give an overview of this circle of ideas (much of which isnot new in the symplectic literature).  Any new content discussed in thistalk is joint work with (subsets of) Benjamin Gammage, Justin Hilburn,Christopher Kuo, David Nadler and Vivek Shende.</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_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. Andreas Hohl (TU Chemnitz)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Of rainbows and rings: The mathematics of the Stokes phenomenon</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In 1857, while investigating the asymptotic behaviour of certain integrals from optics, George G. Stokes encountered a curious analytic phenomenon – a discovery that many decades later turned out to be the key for a classification of linear complex differential equations. This talk will gently survey the history of the Stokes phenomenon and of algebraic approaches to differential systems, from Airy through Hilbert to modern results in Algebraic Analysis.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Room B6</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, March 25      </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"> Yash  Lodha (University of Hawaii at Manoa)</div><div class="event_title">The space of enumerated groups and Rubin\'s theorem <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In 1989, Matatyahu Rubin proved a remarkable theorem showing that if a group admits a faithful action by homeomorphisms on a locally compact,Hausdorff space satisfying some dynamical hypothesis, then such an action is unique up to topological conjugacy (indeed even the space on which it acts in this manner is uniquely determined up to homeomorphism). In this talk we shall study this theorem and some key ideas of the proof, and investigate whether generic groups in a natural Polish topology on countable enumerated groups admit such an action.</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"> Marie-Pier  Côté  (University of Laval, Québec)</div><div class="event_title">Selection bias in insurance: why portfolio-specific fairness fails to extend market-wide <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Fairness centres on people. In insurance, the scope of fairness should be the entire insured population, not solely an insurer\'s clients. However, each insurance company’s portfolio represents a possibly skewed subsample. We examine how portfolio composition affects fair premium methodologies for mitigating direct and indirect discrimination on a protected attribute. We illustrate how unfairness mitigation based on a selection-biased portfolio does not yield a fair market from the perspective of insureds. Relying on causal inference and a portfolio composition indicator, we describe the selection mechanism and determine conditions under which each bias affects various fairness-adjusted premiums. We propose a method to recover the population-wide fairness-adjusted premiums from selection-biased data, by using a (third-party provided) unbiased estimate of the prohibited attribute distribution. We show that this approach effectively mitigates selection bias but leads to overall premiums that are not balanced.</div><div class="event_time">11:00 &bull; EPF Lausanne, Extranef 125</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"> Peter Stevenhagen (Leiden)</div><div class="event_title">Global to local obstructions for primitivity  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />An integer is called a primitive root modulo a prime number p when its reduction generates the multiplicative group of the field ofp elements.Similarly, a point on an elliptic curve over Q is called a primitive point modulo p when its reduction generates the point group of the elliptic curve modulo p.Proving that a given integers is a primitive root modulo infinitely many primes can only be done under the assumption of Riemann hypotheses, and proving primitivity of a given point modulo infinitely many primes is currently beyond our technical means.Contrary to this, proving that primitivity occurs only modulo finitely many primes tends to be easy, as it is implied by global properties of a “finite" kind.I will discuss such global properties, which can be of a non-trivial group theoretical nature.This lecture is based on joint work with Francesco Campagna, Francesco Pappalardi and Nathan Jones.</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/math/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Nikolay Perry (UniGE)</div><div class="event_title">Factorization Homology: an Introduction <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Factorization homology is a gadget which pairs geometric data in the form of an n-manifold (possibly with tangential structure) with appropriate algebraic data, giving an object in a symmetric monoidal (higher) category. Importantly, this gadget satisfies a local-to-global gluing principle: an appropriate notion of excision generalising the Eilenberg-Steenrod axioms. Naturally a higher-categorical theory, this framework has been used in approaches to various quantisation problems and in the construction of fully extended TFTs. The aim of this talk is to give a brief introduction to the theory of factorization homology, introducing important background concepts and examples in advance of Jan Pulmann\'s talk.</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_dis"><a class="external" href="https://unidistance.ch">UniDistance Suisse</a></div><div class="event_type"><a class="external_nolink">Number Theory Seminar</a></div><br /><div class="event_speaker"> Ting-Han  Huang  (Paris XIII)</div><div class="event_title">On p-adic Gross–Zagier formulae for two triple product p-adic L-functions attached to finite slope families <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 briefly explain the works in the thesis and a recent paper (with A. Kazi) of the speaker, which revolve around the p-adic Gross–Zagier formula for (twisted) triple product p-adic L-functions attached to finite slope families.  We will skip the geometric part of the story and focus instead on the computation of the polynomial q-expansions. In the end, we will demonstrate the relation between the special values of p-adic L-functions and the syntomic Abel–Jacobi images of diagonal cycles.</div><div class="event_time">15:00 &bull; <a class="external" href="fernuni.zoom.us/my/davidloeffler">UniDistance Suisse, online</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/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Jill  Pipher (Brown University)</div><div class="event_title">A parabolic Regularity problem: nontangential estimates on the gradient of solutions <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> In recent joint work with M. Dindos and L. Li, we show that the Regularity problem for a second order divergence form parabolic operator is solvable when the data belongs to an appropriate L^p space. The parabolic operator has coefficients that vary in both space and time, and satisfy a certain minimal smoothness assumption defined by a Carleson measure condition - one that has been well-studied for the elliptic analog of these equations. The long term goal, of which this is a step, is to bring the parabolic theory to the level of understanding that has now been achieved for elliptic boundary value problems and beyond, to free boundary problems.  </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_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://sites.google.com/view/agms-fribourg-seminars/home">Seminar Analysis and geometry on metric spaces</a></div><br /><div class="event_speaker"> Dragomir Saric (CUNY)</div><div class="event_title">The Fenchel-Nielsen parameters for infinite Riemann surfaces and the geodesic flow <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />An infinite Riemann surface is parabolic if it does not support Green’s function. Hopf-Tsuji-Sullivan theorem states that X is parabolic iff the geodesic flow is ergodic iff the Brownian motion on X is recurrent iff the covering Fuchsian group is of divergence type. We consider the question of determining whether an explicitly given Riemann surface (in terms of Fenchel-Nielsen parameters) is parabolic. Some sufficient conditions are obtained depending on the size of the lengths and choice of relative twists. We also solve a conjecture of Kahn and Markovic by showing that lengths can be arbitrarily large while the surface remains parabolic when the twists are appropriately chosen.</div><div class="event_time">15:15 &bull; Université de Fribourg, PER23 room 0.05</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/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Jan  Pulmann (Mittag-Leffler Institute, Stockholm)</div><div class="event_title">Deformation quantization of categories and moduli spaces of flat connections <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Factorization homology can be used to assign functorial invariants to surfaces, starting from a braided monoidal category. If this category is obtained by deforming a symmetric monoidal category, this deformation can be tracked through factorization homology. Applying this to the cases of the Drinfeld-Jimbo quantum groups and Drinfeld\'s quasi-triangular quasi-Hopf algebras, we obtain the  Fock-Rosly and the Alekseev-Malkin-Meinrenken bivectors as well as their quantizations, in terms of fusion and skein theory. Based on joint work with Eilind Karlsson, Corina Keller and Lukas Mueller [arxiv:2410.12516].</div><div class="event_time">16:10 &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://www.math.uzh.ch/mat075.1">Zurich Graduate Colloquium</a></div><br /><div class="event_speaker">Barbara Palumbo (University of Genoa)</div><div class="event_title">What is... Applied Mathematics in Solar Physics? <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 my research on the application of mathematical techniques to the analysis of data from STIX and HXI, two indirect imagers that measure X-rays emitted by the Sun during solar flares. The presentation will introduce the underlying physical problem, followed by a mathematical formulation that leads to an ill-posed inverse problem. I will discuss the stability of the problem and explore suitable algorithms for its solution. Finally, I will showcase preliminary reconstructions obtained by applying these methods to real observational data.</div><div class="event_time">16:30 &bull; UZH Zentrum, Building KO2, Room F 150</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, March 26      </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"> Adam Kanigowski (University of Maryland)</div><div class="event_title">Sparse Equidistribution Problems in Dynamics</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/labs/mathicse/">Computational Science and Engineering </a></div><br /><div class="event_speaker"> Zebang  Shen  (ETHZ)</div><div class="event_title">Poincare Inequality for Local Log-Polyak-&#321;ojasiewicz Measures: Non-asymptotic Analysis in Low-temperature Regime <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Potential functions in highly pertinent applications, such as deep learning in over-parameterized regime, are empirically observed to admit non-isolated minima. To understand the convergence behavior of stochastic dynamics in such landscapes, we propose to study the class of log-P&#321;&#8728; measures &#956;&#1013;&#8733;exp(&#8722;V/&#1013;), where the potential V satisfies a local Polyak-&#321;ojasiewicz (P&#321;) inequality, and its set of local minima is provably connected. Notably, potentials in this class can exhibit local maxima and we characterize its optimal set S to be a compact C2 embedding submanifold of Rd without boundary. The non-contractibility of S distinguishes our function class from the classical convex setting topologically. Moreover, the embedding structure induces a naturally defined Laplacian-Beltrami operator on S, and we show that its first non-trivial eigenvalue provides an &#1013;-independent lower bound for the Poincaré constant in the Poincaré inequality of &#956;&#1013;. As a direct consequence, Langevin dynamics with such non-convex potential V and diffusion coefficient &#1013; converges to its equilibrium &#956;&#1013; at a rate of O&#771; (1/&#1013;), provided &#1013; is sufficiently small. Here O&#771;  hides logarithmic terms. </div><div class="event_time">11:15 &bull; EPF Lausanne, CM 1 517</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. Nattalie Tamam (Imperial College London)</div><div class="event_title">Markoff triples and their connection to orbits of the mapping class group <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Markoff triples are the natural solutions of the Markoff relation $x^2+y^2+z^2=3xyz$. They can be viewed as points in the orbit of the mapping class group acting on the character variety of the punctured torus. In this case the action is transitive. However, when considering surfaces with a higher genus or number of holes, this is no longer the case. We will discuss the possible orbits closures of the general case; the algebraic relations that are preserved under the action and the exceptional cases. This is a joint work with Alireza Salehi-Golsefidy.</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. Jeremy Feusi (ETH Zürich)</div><div class="event_title">Tautological projection and the homomorphism property revisited</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"> Shuchen Guo (University of Oxford)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-shuchen-guo-university-of-oxford/">Recent Progress on the Mean-Field Derivation of the Space-Homogeneous Landau Equation</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the Kac model for the space-homogeneous Landau equation with the Coulomb potential. We show that the Fisher information of the Liouville equation for the unmodified N-particle system is monotonically decreasing in time. The monotonicity ensures the compactness to derive a weak solution of the Landau hierarchy.</div><div class="event_time">14:15 &bull; Universität Basel, Spiegelgasse 5, Seminarraum 05.002</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"> Yash Lodha (University of Hawaii at Manoa)</div><div class="event_title">Two new constructions of finitely presented infinite simple groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will describe two new constructions of finitely presented infinite simple groups. First, I will present a construction of finitely presented (and type F<sub>&infin;</sub>) simple groups that act by orientation preserving homeomorphisms on the real line. These are the first such examples. Next, I will present a construction of a family of finitely presented infinite uniformly simple groups, where the Ulam width can get arbitrarily large. Among the class of finitely generated (but not finitely presentable) groups, the existence of such examples was demonstrated in the work of Ivanov from 1989. Our construction provides the first such family of examples in the class of infinite finitely presented groups. This is joint work with James Hyde.</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">Dr. Nicolas Boullé (Imperial College London)</div><div class="event_title">Operator learning without the adjoint <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />There is a mystery at the heart of operator learning: how can one recover a non-self-adjoint operator from data without probing the adjoint? Current practical approaches suggest that one can accurately recover an operator while only using data generated by the forward action of the operator without access to the adjoint. However, naively, it seems essential to sample the action of the adjoint for learning time-dependent PDEs. In this talk, we will first explore connections with low-rank matrix recovery problems in numerical linear algebra. Then, we will show that one can approximate a family of non-self-adjoint infinite-dimensional compact operators via projection onto a Fourier basis without querying the adjoint.</div><div class="event_time">16:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.2</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Prof. Dr. Nicolas Curien (Equipe Probabilités et Statistique, Université Paris-Sud Orsay)</div><div class="event_title">Scaling limits of the Luczak-Winkler growth algorithm <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Since the pioneering work of Aldous in the 1990s, it has been well established that large random trees converge towards a universal object: the Brownian tree. This object, which has become a pillar of modern probability, is a real random compact tree of fractal dimension 2. In this presentation, we will focus on different tree growth algorithms, such as the Rémy algorithm and the Luczak-Winkler algorithm. We will see how, by passing them to the limit, they give rise to diffusions taking  values in the space of real trees, of which the Brownian tree constitutes the invariant law.</div><div class="event_time">17:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room  H12</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, March 27      </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://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"> Jiangfan Yuan (Université Paris-Saclay)</div><div class="event_title">The Langlands formula and perverse sheaves <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We start by introducing a formula of Gindikin-Karpelevich that expresses the constant term of an Eisenstein series as a product of Gamma functions, which is later reinterpreted by Langlands using Satake isomorphism in his famous work of Euler products. This formula reflects a phenomenon of "wall-crossing" that occurs in many situations that concern parabolic induction/restriction. I will introduce a joint work with M.Kapranov, V. Schechtman and O.Schiffmann in which for a reductive group G, we construct a so-called Perverse Coxeter category that encodes behavior of parabolic induction/restriction and relate it with the perverse sheaves on the configuration space h/W. If time permits, we will discuss the relation of our category with operads and some interpretation in geometric Langlands program.</div><div class="event_time">13:15 &bull; EPF Lausanne, CM 1 517</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">Prof. Dr. Irene Waldspurger (CEREMADE (Université Paris-Dauphine))</div><div class="event_title">Correctness guarantees for the Burer-Monteiro heuristic on MaxCut-type problems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Since numerically solving high-dimensional semidefinite programs is challenging, solvers should exploit the structure of the problem at hand, when it allows for speedups. In this talk, we will consider the setting where we have the a priori information that the solution is of low rank (for instance, rank 1). A standard way to exploit this information is through the Burer-Monteiro factorization: we represent the unknown matrix as a product of "thin" matrices (i.e. with few columns); then, we optimize the factors instead of the whole square matrix. This technique reduces the dimensionality of the problem, allowing for important computational savings. However, it makes the problem non-convex, thereby possibly introducing non-optimal critical points which can cause the solver to fail.With Faniriana Rakoto Endor, we have considered the specific category of so-called "MaxCut-type" semidefinite problems. We have exhibited a simple property which guarantees that the resulting non-convex problem has no non-optimal critical point, and hence ensures the success of the algorithm.</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_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"> Hendrik Lenstra (Leiden)</div><div class="event_title">On an old theorem of Jacobson <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It is well-known and easy to prove that any ring inwhich every element equals its own square is commutative.Proving the same thing with "square" replaced by "cube" isalready more complicated, and the difficulties increase withhigher powers.Using his theory of algebras with vanishing radicals,Jacobson proved in 1945 that every ring in which each elementequals some power of itself, with an exponent that is greaterthan 1 but that may depend on the element, is necessarilycommutative. The lecture is devoted to a novel proof that, otherthan existing proofs, has attractive algorithmic features. Inparticular, it gives rise to a method that, when the exponent inJacobson\'s theorem is fixed and given, constructs a perfectlyelementary proof that depends on no more than ring-theoreticidentities.The lecture is based on joint work with Mike Daas, LarsPos, and Samuel Tiersma.</div><div class="event_time">15:00 &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/math/annonces/seminaire-danalyse-numerique">Séminaire d\'Analyse Numérique </a></div><br /><div class="event_speaker"> Eugen  Bronasco (Université de Genève)</div><div class="event_title">Algebraic structures and numerical methods for invariant measure sampling of Langevin dynamics <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Sous réserve de l\'autorisation de soutenance délivrée par la Faculté.Directeur de thèse: Gilles VilmartCo-directeur de thèse: Dominique Manchon</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_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Dr. Mitchell Taylor (ETH)</div><div class="event_title">Sharp well-posedness for the free boundary MHD equations <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will discuss a series of recent works written jointly with M. Ifrim, B. Pineau and D. Tataru where we develop a new \\emph{fully Eulerian} approach to free boundary fluid dynamics, obtaining the first sharp well-posedness theorems for the free boundary Euler and MHD equations. Our well-posedness theories include (i) Local well-posedness in the Hadamard sense, i.e., local existence, uniqueness, and the first proof of continuous dependence on the data, all at optimal Sobolev regularity; (ii) Enhanced uniqueness: Our uniqueness result holds at the level of scaling, requiring merely integrability in time of the Lipschitz norm of \\((v,B)\\) and the \\(C^{1,\\frac{1}{2}}\\) norm of the free surface; (iii) Stability bounds: We construct a nonlinear functional which measures, in a suitable sense, the distance between two solutions (even when defined on different domains) and we show that this distance is propagated by the flow; (iv) Energy estimates: We prove refined, essentially scale invariant energy estimates for solutions, relying on a newly constructed family of elliptic estimates; (v) Continuation criterion: We give the first proof of a sharp continuation criterion in the physically relevant pointwise norms, at the level of scaling. In particular, for the Euler equations we show that solutions can be continued as long as the velocity is in \\(L_T^1W^{1,\\infty}\\), the free surface is in \\(L_T^1C^{1,\\frac{1}{2}}\\) and the surface does not self-intersect; (vi) A novel construction of regular solutions, which was not known at any regularity for MHD.</div><div class="event_time">16:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 46</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-financial-and-insurance-mathematics">Talks in Financial and Insurance Mathematics</a></div><br /><div class="event_speaker">Dr. Florian Huber (EPFL)</div><div class="event_title">An analyst\'s perspective on Markovian lifts of stochastic Volterra equations <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We investigate Markovian lifts of stochastic Volterra equations(SVEs) with completely monotone kernels and general coefficients within the framework of weighted Sobolev spaces. Our primary focus is developing a comprehensive solution theory for a class of non-local stochastic evolution equations (SEEs) encompassing these Markovianlifts. This enables us to extend known results for the lifted equation such as existence of solutions and of invariant measures. Additionally our Framework allows us to obtain an Itô-type formula for the stochastic Volterra equations.</div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, March 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"> Boris Bukh (Carnegie Mellon University)</div><div class="event_title">Discrete Geometry</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_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"> Daniel Potts (TU Chemnitz)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-in-numerical-analysis-daniel-potts-tu-chemnitz/">High dimensional approximation and applications</a> <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 present algorithms for the approximation of multivariate functions. We start with the approximation by trigonometric polynomials based on sampling of multivariate functions on rank-1 lattices or on scattered data. To this end, we study the approximation of functions in periodic Sobolev spaces of dominating mixed smoothness. The proposed algorithm based mainly on a fast Fourier transforms, and the arithmetic complexity of the algorithm depends only on the cardinality of the support of the trigonometric polynomial in the frequency domain. After a detailed introduction we will focus on the following questions in more detail. We discuss methods where the support of the trigonometric polynomial is unknown. We present a method based on the analysis of variance (ANOVA) decomposition that aims to detect the structure of the function, i.e., find out which dimension and dimension interactions are important. This information is then utilized in obtaining an approximation for the function. Based on these methods we develop an efficient, non-intrusive, adaptive algorithm for the solution of elliptic partial differential equations. For further information about the seminar, please visit this webpage .</div><div class="event_time">11:00 &bull; Universität Basel, Room 05.001, Spiegelgasse 5, 4051 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"> Valeria  Banica  (Sorbonne University)</div><div class="event_title">Title T.B.A.</div><div class="event_time">14:15 &bull; EPF Lausanne</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://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. Gergely  Harcos (Alfréd Rényi Institute of Mathematics)</div><div class="event_title">A new zero-free region for Rankin–Selberg L-functions <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will present a new zero-free region for all GL(1)-twists of GL(m)×GL(n) Rankin–Selberg L-functions. The proof is inspired by Siegel’s celebrated lower bound for Dirichlet L-functions at s=1. I will also discuss briefly some applications and a very recent development. Joint work with Jesse Thorner.</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://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Rahul Pandharipande (ETH Zürich)</div><div class="event_title">Geometry of the universal Jacobian</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>';