var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-19"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-17"><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. 14</span>      <span style="float: right; text-align:right; width: 250px;">16.12 - 20.12.2024</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Autumn Semester 2024</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, December 16      </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"> Tom Mrowka (Massachusetts Institute of Technology)</div><div class="event_title">Floer homology of three manifolds and applications to low dimensional topology <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Floer homology and the related invariants of 4-manifolds has given us deep insight in smooth differential topology in dimensions 3 and particularly 4. The theory has yielded insights like existence of exotic differentiable structures on 4 dimensional euclidean space, complex curves minimize genus in complex projective space, killing the Hauptvermuntung, there even appear to be connection to the 4 color map theorem. This course will build up Floer homology of three manifolds from scratch. The focus will be on Instanton Floer homology but we will mention other versions and develop applications as the course goes on.</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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> Eleonore Bach</div><div class="event_title">Smoothed analysis of the Simplex method: nearly tight noise dependence <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Smoothed analysis is a method for analysing the performance of algorithms, used especially for those algorithms whose running time in practice is significantly better than what can be proven through worst-case analysis. Given an arbitrary linear program with $d$ variables and $n$ inequality constraints, we prove that there is a simplex method with smoothed complexity upper bounded by $O(\\sigma^{-1/2} d^{11/4} \\log(n/\\sigma)^{7/4})$ pivot steps improving over the current best bound of $O(\\sigma^{-3/2} d^{13/4} \\log(n)^{7/4})$ pivot steps due to Huiberts, Lee and Zhang (STOC \'23).    For the same method we prove a lower bound on its smoothed complexity of $0.03 \\sigma^{-1/2} d^{-1/4}\\ln(n)^{-1/4}$ pivot steps for $n = (4/\\sigma)^d$ inequality constraints. Here $\\sigma > 0$ is the standard deviation of Gaussian distributed noise added to the original LP data.    This nearly closes the gap between the upper and lower bounds in regards to their dependence on the noise parameter $\\sigma$. In this talk we will discuss the algorithmic improvements that we used for the above new upper bound. This is joint work with Sophie Huiberts.</div><div class="event_time">11:00 &bull; EPF Lausanne, INJ114</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/talks-in-mathematical-physics">Talks in Mathematical Physics</a></div><br /><div class="event_speaker"> Konstantin Wernli (Centre for Quantum Mathematics, University of Southern Denmark)</div><div class="event_title">Gluing formulas for heat kernels <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Abstract: Motivated by heat kernel renormalization of perturbative quantum field theory, we study the cutting and gluing behaviour of the heat kernel on a Riemannian manifold $M$ which is cut along a compact hypersurface $\\gamma$ into two Riemannian manifolds $M_1$, $M_2$. Under a certain assumption on $(M,\\gamma)$ (which we conjecture to be true for all Riemannian manifolds), we prove a gluing formula for the heat kernel which involves only the heat kernels on $M_1, M_2$ and $\\gamma$. This is a joint work with Pavel Mnev, arxiv:2404.00156. </div><div class="event_time">13:30 &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_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"> Thibaut  Lunet (TU Hamburg)</div><div class="event_title">Toward the use of Machine-Learning models to improve the initial guess of iterative time-integration schemes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The recent impressive advances in machine-learning (ML) driven applications and the wide accessibility of the associated development tools has motivated many parts of the scientific community to explore potential applications of ML in research. The one we are considering is to use a ML prediction to estimate the initial guess of a Spectral Deferred Correction time integration scheme at each time-step, that could permit a faster convergence to an accurate solution and / or better numerical stability and performance. The PDE considered is a Rayleigh-Benard convection between two plates, solved using pseudo spectral methods implemented in the Dedalus software.We will present the challenges induced by this application, the most recent results found and problems encountered, and discuss the perspectives of such introduction of ML-based approaches in computational mathematics. Finally, we will give context to this (still) open question: can a ML-model simply replace all the numerical algorithms that have been developed over the last 100 years ...</div><div class="event_time">15:00 &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/symplectic-geometry-seminar">Symplectic Geometry Seminar</a></div><br /><div class="event_speaker"> Tom Mrowka (MIT)</div><div class="event_title">Instanton Floer homology for 3-manifolds, knot and webs: what’s next? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Floer homology in its Monopole, Heegard and ECH version’s has proved a powerfultool for the study of the geometry and topology of three manifolds.  Their older cousin instantonFloer homology also has its share of trophies but remains more mysterious and harder to compute.  This talk will survey a few highlights of applications of the theory and problems that remain to be solved and prospects for the future.</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://sites.google.com/view/pm-seminar/home">Physical Mathematics Seminar</a></div><br /><div class="event_speaker"> Lucas Rey (Paris)</div><div class="event_title">Trees, forests and Doob transform <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> The study of spanning trees dates back at least to the matrix-tree theorem of Kirchoff (1847). This theorem gives a determinantal formula for the number of spanning trees of a given graph. The study of random spanning trees (RST) was pushed further, using tools such as the transfer current theorem, or the Wilson’s algorithm which  samples RST using random walks. Another important tool for planar graphs is the Temperley’s bijection between spanning trees and dimer covers of an associated graph. More recently, in dimension 2, the scaling limit was established by Werner, Schramm, Lawler (2004) and universality results were also proved.Spanning forests generalize spanning trees, and some of the tools mentioned above (but not all !) also apply to forests.In this talk, we will explain how to use the Doob transform (or h-transform) to transfer the tools from the trees to the forests. As an application, we will present a universality result for the near-critical scaling limit of the RST model in dimension 2. </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_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. Sara Kališnik Hintz (ETH Zürich)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">On the Applications of Topology</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In recent years, techniques originating in topology have been adapted to the study of large and complex data sets. In this talk I will present two of the most prominent topological methods: persistent homology and mapper. I will also show numerous applications to computer vision, biology, medicine etc. and briefly explain how they can be used in combination with traditional machine learning techniques.</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, December 17      </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"> Gigliola Staffilani (Massachusetts Institute of Technology)</div><div class="event_title">Dispersive equations and wave turbulence theory <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this course we will investigate questions of weak turbulence theory by using as explicit example of wave interactions the solutions to periodic and nonlinear Schrödinger equations. We will start with Strichartz estimates on periodic setting, then we will move to well-posedness.We will then present two different ways of introducing the evolution of the energy spectrum. We will first work on a method proposed by Bourgain and involving the growth of high Sobolev norms. Then, we will give some ideas of how to derive rigorously the effective dynamics of the energy spectrum itself (wave kinetic equation), when one considers weakly nonlinear dispersive equations.  </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"> Andrés  Navas  (Universidad de Santiago de Chile)</div><div class="event_title">The asymptotic variation of a 1-D diffeomorphisms and the growth of derivatives <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Since the work of Denjoy, it is known that in 1-D dynamics it is very important to look at the variation of the logarithm of the derivative in order to control the distortion under the dynamics. However, since this variation is subadditive, it is very natural to look at its stable version, namely the asymptotic growth of it under iteration.  We call this number the asymptotic variation. We will discuss some of its basic properties, as well as several applications and possible extensions. </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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> Orr  Paradise</div><div class="event_title">Models that prove their own correctness <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This talk introduces Self-Proving models, a new class of models that formally prove the correctness of their outputs via an Interactive Proof system. After reviewing some related literature, I will formally define Self-Proving models and their per-input (worst-case) guarantees. I will then present algorithms for learning these models and explain how the complexity of the proof system affects the complexity of the learning algorithms. Finally, I will show experiments where Self-Proving models are trained to compute the Greatest Common Divisor of two integers, and to prove the correctness of their results to a simple verifier.No prior knowledge of autoregressive models or Interactive Proofs will be assumed of the listener. This is a joint work with Noga Amit, Shafi Goldwasser, and Guy Rothblum.</div><div class="event_time">11:00 &bull; EPF Lausanne, BC 420</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"> Joackim Bernier (Nantes Université)</div><div class="event_title">Infinite dimensional invariant tori for nonlinear Schrödinger equations <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Almost periodic solutions are expected to be typical for nearly integrable Hamiltonian PDEs but as yet very little is known about their existence. In this talk, I will present a recent result about the existence of some almost periodic solutions for nonlinear Schrödinger equations on the circle. Our proof relies on KAM theory and on some dispersive smoothing effects that I will describe.</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_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"> Pierre de la Harpe (Université de Genève)</div><div class="event_title">Homéomorphismes minimaux de l’espace de Cantor, modèles de Bratteli-Vershik <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Une première partie de l\'exposé décrit une construction d\'homéomorphismes minimaux de l\'espace de Cantor ; la construction est due à Vershik et utilise des graphes introduits par Bratteli. Une seconde partie esquisse un résultat de Hermann, Putnam et Skau qui établit que tout homéomorphisme minimal du Cantor est conjugué à un homéomorphisme de Bratteli--Vershik.</div><div class="event_time">14:00 &bull; Université de Genève, Conseil Général 7-9, Room 6-13</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Gerard Orriols Gimenez (ETHZ)</div><div class="event_title">Area minimization among Lagrangian and Legendrian submanifolds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will introduce the problem of minimizing area among Lagrangian submanifolds in a Riemannian symplectic manifold, and the related problem for Legendrian submanifolds in a contact manifold, which can be seen as integral currents in a metric space locally modeled on the Heisenberg group. This constrained variational problem was introduced by Schoen and Wolfson with the aim of constructing Lagrangian minimal surfaces and Special Lagrangians. I will explain the connection between the Lagrangian and Legendrian problem, what is known in two dimensions, what goes wrong in higher dimension and some new progress in this direction.</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"> Yanpeng  Li  (Sichuan University)</div><div class="event_title">Polynomial integrable systems from cluster structures <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We present a general framework for constructing polynomial integrable systems with respect to linearizations of Poisson varieties that admit log-canonical coordinate systems. Our construction is in particular applicable to Poisson varieties with compatible cluster or generalized cluster structures. As examples, we consider an arbitrary standard complex semi-simple Poisson Lie group G with the Berenstein-Fomin-Zelevinsky cluster structure, nilpotent Lie subgroups of G associated to elements of the Weyl group of G, identified with Schubert cells in the flag variety of G and equipped with the standard cluster structure (defined by Geiss-Leclerc-Schröer in the simply-laced case), and the dual Poisson Lie group of GL(n, C) with the Gekhtman-Shapiro-Vainshtein generalized cluster structure. In each of the three cases, we show that every extended cluster in the respective cluster structure gives rise to a polynomial integrable system on the respective Lie algebra with respect to the linearization of the Poisson structure at the identity element. This is joint work with Yu Li and Jiang-Hua Lu.</div><div class="event_time">15:30 &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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Dr. Denis Nesterov (ETH Zürich)</div><div class="event_title">Stable maps and admissible covers  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Moduli spaces of stable maps and admissible covers of a curve give rise to interesting cycles on moduli spaces of stable curves. The talk will be about a wall-crossing formula relating these two types of cycles. Based on a joint work with Max Schimpf. </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_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">Ludovica Buelli (University of Genoa)</div><div class="event_title">What is... Hyperkähler Geometry? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />manifolds, both from a complex analytic and algebraic point of view. This kind of manifolds plays a central role in classification problems in complex algebraic geometry, being fundamental building blocks of Ricci-flat manifolds, and their theory has become a very popular research topic in the last years. Together with their definition(s) and their main properties, we will see the four known families of deformation classes of this kind of manifolds and we will approach the problem of their bimeromorphic classification.</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, December 18      </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"> Masoud Kamgarpour</div><div class="event_title">Towards reductive generalisations of Kac’s polynomials <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In 1980 Victor Kac proved that the number of indecomposable representations of a quiver over a finite field is a polynomial.The desire to understand this polynomial has been a key driving force in geometric representation theory, cf. Schiffmann’s 2018 ICM. Quiver varieties are by construction type A objects, i.e. attached to the group GL_n. In this talk we explore what the reductive analogue of Kac polynomials can be. We restrict to certain quivers that are called star shaped quivers. Here a theorem of Hausel, Letellier and Villegas relates Kac’s polynomial to the number of points of moduli of representations of connections on vector bundles on surfaces. Replacing vector bundles by G-bundles allows us to explore the G-analogues of Kac’s polynomials. This talk is based on the arXiv preprint: https://arxiv.org/abs/2409.04735</div><div class="event_time">10:15 &bull; EPF Lausanne, CM 1 100</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/cmgr/cmgr/geometry-seminar">Geometry Seminar</a></div><br /><div class="event_speaker"> Anders Karlsson (University of Geneva)</div><div class="event_title"><a class="external" href="https://www.epfl.ch/labs/cmgr/cmgr/geometry-seminar/">A fixed point theorem for isometries</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A new fixed-point theorem will be explained asserting that every isometry of a metric space has a fixed-point in the metric compactification of (the injective hull of) the space. In case the metric space admits a conical bicombing there is no need for passing to the injective hull, examples of such spaces include all Banach spaces, CAT(0)-spaces, injective metric spaces, spaces of positive operators, as well as convex subsets and products thereof. The central notion is that of a metric functional which is an extension of Busemann’s and Gromov’s horofunctions. The result is in particular new for infinite-dimensional Banach spaces and non-proper CAT(0)-spaces. As a consequence, well-known fixed-point free examples get their fixed-point as it were. A new mean ergodic theorem generalizing von Neumann’s is another direct consequence. A more elaborate corollary is that every invertible bounded linear operator of a Hilbert space admits a non-trivial invariant metric functional on the symmetric space of positive operators.   </div><div class="event_time">11:15 &bull; <a class="external" href="https://plan.epfl.ch/?room==CH%20B3%2031">EPF Lausanne, CH B3 31</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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Dr. Sam Canning (ETH Zürich)</div><div class="event_title">Cycles on moduli spaces of curves and abelian varieties <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> I will show how the study of non-tautological classes on the moduli space of abelian varieties helps explain the structure of the tautological ring of the moduli space of curves of compact type. On the curves side, this is joint work with Hannah Larson and Johannes Schmitt, and on the abelian varieties side, it is joint with Dragos Oprea and Rahul Pandharipande.</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G G43</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">Blerim Alimehaj</div><div class="event_title">\\(b\\)-Symbol Weight Distribution of Irreducible Cyclic Codes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />As our technology advances, the need for \\(b\\)-symbol read channels that can handle messages with high-density data becomes crucial. The problem with conventional read channels is that they are more likely to overlap multiple information units, also called symbols, while reading messages with high-density data. The idea behind \\(b\\)-symbol read channels is that these channels consider all \\(b\\) consecutive symbols from the sent message as one symbol. This protects the message from being read with overlapping symbols. Considering a code word of some code \\(\\mathcal{C}\\) as the sent message, the message read by some \\(b\\)-symbol read channel is called a \\(b\\)-symbol code word. In this thesis, we investigate \\(b\\)-symbol codes over semiprimitive irreducible cyclic codes and their Hamming weight distribution. The \\(b\\)-symbol Hamming weight distribution of semiprimitive irreducible cyclic codes is determined up to an invariant that we call \\(\\mu(b)\\) and \\(\\mu_l (b)\\). These invariants depend on \\(b\\) and on the choice of the primitive element that we use to describe the irreducible cyclic code\\(\\mathcal{C}\\). This thesis aims to find lower and upper bounds of the average values of these invariants. To do so, we use algebraic function field theory and number theory. In this thesis, we obtain several lower and upper bounds, test their performance for smaller fields, and compare them. Furthermore, we are able to improve those bounds due to a number theoretic approach. Using these bounds, we are able to deduce a very good estimate for the average values of the invariants \\(\\mu(b)\\) resp. \\(\\mu_l (b)\\). These results provide a better understanding of the \\(b\\)-symbol Hamming weight distribution of semiprimitive irreducible cyclic codes.</div><div class="event_time">15:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 28</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"> Andrew Lobb (Durham University, UK)</div><div class="event_title">Symplectic geometry and peg problems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Square Peg Problem (SPP), formulated by Toeplitz in 1911 and still unsolved, asks whether every Jordan curve contains four points at the vertices of a square. We shall discuss how, when the Jordan curve is smooth, SPP and related peg problems can be interpreted as questions in symplectic geometry, and deduce some consequences both for smooth curves and for other classes. Joint work with Josh Greene.</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_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://memento.epfl.ch/event/probability-and-stochastic-analysis-seminar/">Probability (and Stochastic Analysis) Seminar </a></div><br /><div class="event_speaker"> Ilya Chevyrev (TU Berlin and University of Edinburgh)</div><div class="event_title"> Large field problem for SPDEs by scaling <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 show a simple approach to deriving a priori bounds for coercive SPDEs based on scaling. The basic idea is that one first shows bounds for the equation with a small noise and then "rescales" the bounds back to a global scale. Although many equations that the approach can handle have been treated recently with other methods, the advantages of the approach by scaling is that it is quite simple and allows one to state a single result that simultaneously covers different equations, such as ODEs and parabolic PDEs. Based on work in progress with Massimiliano Gubinelli.</div><div class="event_time">16:00 &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://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">Luana Kurmann</div><div class="event_title">Cayley Graphs with Large Girth and Constructions of LDPC Codes <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 investigate a particular family of graphs with large girth and look at their applications to low-density parity-check (LDPC) codes. Specifically, we study a family of Cayley graphs with large girth over finite fields with prime order, constructed by Margulis. We analyse Margulis&#039; lower bound for the girth of these graphs and compute the exact girth for several prime numbers. Our results show that the actual girth exceeds the bound by an average of about 87% in all cases studied. We show an improvement to Margulis&#039; bound which leads to an average error rate of about 56%. Additionally, we present further observations which suggest that an even better bound may still exist. Furthermore, we show how LDPC codes can be constructed based on these graphs and simulate their error correction performance over an additive white Gaussian noise channel.</div><div class="event_time">16:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 28</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sam/news-and-events/zhacm-colloquia">Zurich Colloquium in Applied and Computational Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Dirk Pauly (TU Dresden)</div><div class="event_title">Traces for Hilbert Complexes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study a new notion of trace and extension operators for abstract Hilbert complexes.</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://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external_nolink">Paul Bernays Lectures</a></div><br /><div class="event_speaker"> Michel  Devoret (University of California Santa Barbara)</div><div class="event_title">The Physics of Information <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It is often said that we live in an "information society". But what exactly is meant by information? A sequence of symbols 0 and 1? Currently, inside the most miniaturized computer, a binary digit, commonly called a bit, is a complex physical device with billions of interacting particles. What happens to information processing when each bit is carried by a single quantum particle, such as an atom, an electron or a photon? Conversely, can we see the movement of elementary particles as a calculation that the universe is performing? The physics of the last thirty years has been particularly rich in the development of ideas and experiments that have illustrated the crucial role of information in physical laws. A new type of computer, the quantum computer, still in the prototype phase, has been invented. This lecture, which is aimed at non-specialists, will explain the merits of such quantum machine and some of the questions it can tackle. In particular, one crucial aspect of its development, namely the progress in fault-tolerant operations, will be discussed.</div><div class="event_time">17:00 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room F 30</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. Dirk Zeindler (Lancaster University)</div><div class="event_title">Partitions into semi-primes <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 look at some recent developments about integer partitions, including coloured partitions, semi-prime partitions and r-prime partitions.We will give asymptotic formulae for the number of these partitions. We will also look at some interesting elements of the proof of these formulae, without going into too much technical detail.In particular, we have a look at strange and pseudo-differentiable functions.</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, December 19      </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/schools/sb/research/math/statistics-seminars/">Statistics Seminar </a></div><br /><div class="event_speaker"> Alberto  Bietti  (Flatiron Institute)</div><div class="event_title">Associative memories as a building block in Transformers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Large language models based on transformers have achieved great empirical successes. However, as they are deployed more widely, there is a growing need to better understand their internal mechanisms in order to make them more reliable. These models appear to store vast amounts of knowledge from their training data, and to adapt quickly to new information provided in their context or prompt. Through toy tasks for reasoning and factual recall, we highlight the role of weight matrices as associative memories, and provide theoretical results on how gradients enable their learning during training, and how over-parameterization affects their storage capacity.</div><div class="event_time">10:15 &bull; EPF Lausanne, ELA 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_nolink">Paul Bernays Lectures</a></div><br /><div class="event_speaker"> Michel Devoret (University of California Santa Barbara)</div><div class="event_title">Error correction of a logical quantum bit beyond the break-even point <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The accuracy of logical operations on quantum bits (qubits) must be improved for quantum computers to surpass classical ones in useful tasks. To that effect, quantum information needs to be made robust to noise that affects the underlying physical system. Rather than suppressing noise, quantum error correction aims at preventing it from causing logical errors. This approach derives from the reasonable assumption that noise is local: it does not act in a coordinated way on different parts of the physical system. Therefore, if a logical qubit is adequately encoded non-locally in the larger Hilbert space of a composite system, it is possible, during a limited time, to detect and correct the noise-induced evolution before it corrupts the encoded information. We will present an experiment implementing a logical qubit in a superconducting cavity coupled to a transmon synthetic atom – the latter employed here as an auxiliary non-linear element [1]. Error correction involves a novel primitive operation [2] and feedback control based on reinforcement learning [3]. Recently, we have stabilized in real-time a logical qubit manifold spanned by the Gottesman-Kitaev-Preskill grid states, reaching a correction efficiency such that the lifetime of the encoded information was prolonged by more than a factor of two beyond the lifetime of the best physical qubits composing our system.</div><div class="event_time">17:00 &bull; ETH Zentrum, Building HCI, Room G 7</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. Max Nendel (University of Waterloo)</div><div class="event_title">Upper Comonotonicity and Risk Aggregation under Dependence Uncertainty <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 study dependence uncertainty and the resulting effects on tail risk measures, which play a fundamental role in modern risk management. We introduce the notion of a regular dependence measure, defined on multi-marginal couplings, as a generalization of well-known correlation statistics such as the Pearson correlation. The first main result states that even an arbitrarily small positive dependence between losses can result in perfectly correlated tails beyond a certain threshold and seemingly complete independence before this threshold. In a second step, we focus on the aggregation of individual risks with known marginal distributions by means of arbitrary nondecreasing left-continuous aggregation functions. In this context, we show that under an arbitrarily small positive dependence, the tail risk of the aggregate loss might coincide with the one of perfectly correlated losses. A similar result is derived for expectiles under mild conditions. In a last step, we discuss our results in the context of credit risk, analyzing the potential effects on the value at risk for weighted sums of Bernoulli distributed losses. The talk is based on joint work with Corrado De Vecchi and Jan Streicher.</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, December 20      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/seminar-in-numerical-analysis">Seminar in Numerical Analysis</a></div><br /><div class="event_speaker"> Ana Djurdjevac (FU Berlin)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-in-numerical-analysis-ana-djurdjevac-fu-berlin-1/">Quantitative approximation of particle systems through SPDEs</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Interacting particle systems provide flexible and powerful models that are useful in many application areas such as sociology (agents), molecular dynamics (proteins) etc. However, particle systems with large numbers of particles are very complex and difficult to handle, both analytically and computationally. Therefore, a common strategy is to derive effective equations that describe the time evolution of the empirical particle density. A prototypical example that we will consider is the formal identification of a finite system of particles with the singular Dean-Kawasaki equation. We will give a short introduction about the Dean-Kawasaki equation and its applications. Our aim is to introduce a well-behaved nonlinear SPDE that approximates the Dean-Kawasaki equation for a particle system with mean-field interaction both in the drift and the noise term. We want to study the well-posedness of these nonlinear SPDE models and to control the weak error of the SPDE approximation with respect to the particle system using the technique of transport equations on the space of probability measures. This is the joint work with H. Kremp, N. Perkowski and J. Xiaohao. Furthermore, we will discuss possible numerical methods for these problems. In particular, we will focus on hybrid methods. This is a joint work with A. Almgren and J. Bell. For further information about the seminar, please visit this webpage .</div><div class="event_time">11:00 &bull; Universität Basel, DMI, Spiegelgasse 5, 4051 Basel Seminarraum 05.001</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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> Daoyuan  Chen</div><div class="event_title">Parallel and Distributed Expander Decomposition: Simple, Fast, and Near-Optimal <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Expander decompositions have become one of the central frameworks in thedesign of fast algorithms. For an undirected graph G = (V,E), anear-optimal &#966;-expander decomposition is a partition V1,V2,...,Vk of thevertex set V where each subgraph G[Vi] is a &#966;-expander, and only anOe(&#966;)-fraction of the edges cross between partition sets.In this article, we give the first near-optimal parallel algorithm tocompute &#966;-expander decompositions in near-linear work Oe(m/&#966;2) andnear-constant span Oe(1/&#966;4). Our algorithm is very simple and likelypractical. Our algorithm can also be implemented in the distributedCongest model in Oe(1/&#966;4) rounds.Our results surpass the theoretical guarantees of the currentstate-of-the-art parallel algorithms [CS19, CS20], while being the firstto ensure that only an Oe(&#966;) fraction of edges cross between partitionsets. In contrast, previous algorithms [CS19, CS20] admit at least anO(&#966;1/3) fraction of crossing edges, a polynomial loss in qualityinherent to their random-walk-based techniques. Our algorithm, instead,leverages flow-based techniques and extends the popular sequentialalgorithm presented in [SW19].This talk is based on the joint work with Simon Meierhans, MaximilianProbst Gutenberg, Thatchaphol Saranurak.</div><div class="event_time">11:00 &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_nolink">Paul Bernays Lectures</a></div><br /><div class="event_speaker"> Michel Devoret (University of California, Santa Cruz)</div><div class="event_title">Driven unwanted state transitions in superconducting quantum circuits <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Readout and parametric gate operations in qubits implemented in quantum superconducting circuits are performed by applying microwave drive tones to the circuit. The simultaneous pursuit of fidelity and speed of these operations by increasing drive strength is limited by unwanted drive-induced state transitions arising from the circuit non-linearity. We experimentally address the origin of these adverse state transitions in a driven transmon by measuring transition probabilities as a function of drive frequency and power. We show that there are three distinct mechanisms for adverse transitions caused by the drive: 1) AC Stark shift of qubit frequency into resonance with lossy degrees of freedom in the qubit environment, 2) excitation of intrinsic resonances linking computational and non-computational states within the transmon spectrum, 2) non-linear, Raman-like processes involving extrinsic degrees of freedoms such as packaging or transmission line modes. Our findings provide insights into the improvement of readout and gate operations on superconducting qubits.  </div><div class="event_time">17:00 &bull; ETH Zentrum, Building HCI, Room G 7</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>';