var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-8"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-6"><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;">19.5 - 23.5.2025</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, May 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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> Junqiao  Lin  (CWI)</div><div class="event_title">MIPco=coRE and generalized compression framework <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A multiplayer interactive proof system (MIP) is a well-studied complexity class in computational theory. A landmark result by Babai et al. shows that MIP is equivalent to the complexity class NEXP. More recently, a breakthrough by Ji et al. has demonstrated that MIP with quantum (tensor) entanglement, denoted as MIP*, is equivalent to the complexity class RE. This result has profound implications for both the operator algebra and quantum information communities.A key part of this breakthrough involves a compression theorem for nonlocal games, which allows one to embed an instance of the halting problem into an MIP* protocol. In this talk, I will introduce interactive proof systems under various models of entanglement. I will also introduce the generalized compression framework, a generalization of the compression argument used in the MIP*=RE theorem, which could potentially be applied to other complexity classes. Lastly, I will explore how this framework can be used to prove the coRE-completeness of the complexity class MIPco, an MIP protocol where provers are allowed access to the commuting operator model of entanglement.</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/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Qile Chen (Boston College)</div><div class="event_title">Counting curves in critical loci via logarithmic Gauged Linear Sigma Models <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Abstract: Gauged Linear Sigma Models (GLSM) introduced by Witten in the 90\'s can be viewed as a way of counting curves in critical loci of holomorphic functions called superpotentials.  On the mathematical side, the framework of GLSM has been established  by Fan-Jarvis-Ruan and Chang-Li-Li. Compared to other Gromov-Witten type invariants, non-properness in GLSM is a special feature due to non-constant superpotentials. In this talk, I will report on a joint work with Felix Janda and Yongbin Ruan on logarithmic Gauged Linear Sigma Models (log GLSM), which compactify GLSM using stable logarithmic maps of Abramovich-Chen-Gross-Siebert. A key in our construction is a universal logarithmic modification, called the uniform maximal degeneracy, over which superpotentials become well-behaved along logarithmic boundaries. This leads to a reduced perfect obstruction theory of log GLSM, recovering the Kiem-Li cosection localized virtual cycles of GLSM.</div><div class="event_time">15:00 &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" href="https://math.ethz.ch/s/symplectic-geometry-seminar">Symplectic Geometry Seminar</a></div><br /><div class="event_speaker"> Joel Schmitz (Université de Neuchâtel)</div><div class="event_title">Almost Toric Fibrations and Lagrangian Poincaré non-recurrence <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Almost Toric Fibrations (ATFs) are a certain type of integrable system and provide a useful tool to study symplectic four-manifolds, allowing for various explicit constructions of Lagrangian torus knots and interesting symplectomorphisms. The latter gives a counterexample to the Lagrangian Poincaré recurrence conjecture. This talk will give a "users manual" to ATFs, outlining the tools used to manipulate them. </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. Eleonora Sammarchi (University of Bern)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">The MediMath project and the study of proofs in algebra between the 9th and the early 17th century</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />“Medieval and Early Modern Mediterranean Mathematics” (MediMath) is a research project dedicated to the historical study of algebra and its interactions with arithmetic and geometry as developed in the Mediterranean world from the 9th to the early 17th century. In this presentation, I will provide a brief overview of the project, outline its primary objectives, and address some of the methodological challenges associated with the analysis of medieval mathematical texts. The latter part of the talk will explore the various ways in which proofs were conceived within the context of algebra, addressing questions such as: What constituted a proof in medieval algebraic texts? What role did geometrical figures play in algebraic reasoning? And how was generality expressed?</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, May 20      </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"> Daniele D\'Angeli (Università N. Cusano, Rome)</div><div class="event_title">Spectral and distance-spectral properties of the Pauli groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Pauli groups $P_n$ are generalizations of the famous Pauli group $P_1$ involved in quantum mechanics and the formulation of the celebrated Pauli Exclusion Principle. In this talk, I will show how to obtain these groups as iterated central products and this brings out a natural generating system $S_{P_n}$ for such groups which differs from the standard one. Using this approach, we are able to recursively construct the adjacency matrix and the distance matrix of $Cay(P_n,S_{P_n})$ for each $n\\geq 1$, and to explicitly describe their spectra and the associated eigenvectors. Then, some remarkable properties of these spectra and some interesting consequences are discussed.</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_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/algebraische-geometrie/">Seminar Algebra and Geometry</a></div><br /><div class="event_speaker"> Francesco Denisi (Université Paris-Cité)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-algebra-and-geometry-francesco-denisi-paris-cite/">On the birational geometry of some hypersurfaces</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Mori dream spaces form a class of algebraic varieties that play a significant role in birational geometry, as they exhibit ideal behaviour within the minimal model program. In this talk, we first motivate and discuss the notion of a Mori dream space, providing numerous examples and non-examples. We then explore the birational geometry of hypersurfaces in products of weighted projective spaces, as well as in more general ambient spaces, focusing in particular on cases where such hypersurfaces are Mori dream spaces. We generalise results previously obtained by J.C. Ottem and, if time permits, conclude with a few remarks on the Kawamata-Morrison cone conjecture for certain anticanonical Calabi-Yau hypersurfaces in products of weighted projective spaces.</div><div class="event_time">10:30 &bull; Universität Basel, Seminarraum 00.003, Spiegelgasse 1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/annonces/seminaire-danalyse-numerique">Séminaire d\'Analyse Numérique </a></div><br /><div class="event_speaker"> Elias Polak (University of Fribourg)</div><div class="event_title">Real-space machine learning of correlation density functionals <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Machine learning (ML) is increasingly playing a pivotal role in extending the reach of quantum chemistrymethods for both molecules and materials. However, in density functional theory—the primary workhorsefor quantum simulations—using ML to overcome the limitations of human-designed density functionalapproximations (DFAs) remains elusive, as ML-based approximations suffer from severely limitedtransferability to unseen chemical systems. To address this challenge, we explore the application of real-space ML, where energies are learned point-by-point in space through energy densities. This specializedtraining strategy optimizes the learning process of deep neural networks for energy model functions. Central to the real-space learning approach is the derivation and implementation of correlation energy densities thatcorrespond to the density weighted integrands of the correlation energy functional. ML of these energydensities requires a regression norm, identified as the Local Energy Loss (LES) or the global energy loss(GES). The talk will demonstrate how LES dramatically enhances the transferability of ML DFAs byexpanding each system’s single energy data point into thousands of spatial data points. Furthermore, theextrapolation power of LES to unseen chemistry is assessed through unitary integral translations of theenergy density and by varying the numerical settings of the ML process.References[1] S. Vuckovic, T. J. P. Irons, A. Savin, A. M. Teale, and P. Gori-Giorgi, Journal of Chemical Theoryand Computation 12, (2016) 2598-2610.[2] E. Polak, H. Zhao, S. Vuckovic. Real-space machine learning of correlation density functionals,ChemRxiv. 2024; doi:10.26434/chemrxiv-2024-zk6hp-v2</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"> Nicolas Vaskou (UNIGE)</div><div class="event_title">Artin groups and the isomorphism problem <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Artin groups form a quite large family of groups whose interest is rapidly growing in geometric group theory. They are intrinsically related to Coxeter groups. The first goal of this talk will be to introduce these groups along with some of their basic properties (and open conjectures) and their actions on certain CW-complexes. In the second part, we will focus on the isomorphism problem: "When are two Artin groups isomorphic?". This question is open in general, but I will explain what is known along with some recent results.</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_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"> Masafumi Hattori (Nottingham)</div><div class="event_title">K-moduli of quasimaps and quasi-projectivity of K-stable Calabi-Yau fibrations over curves <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />K-stability is an important notion in algebraic geometry, which is introduced to detect the existence of constant scalar curvature Kahler metrics, as the Yau-Tian-Donaldson conjecture predicted. On the other hand, this notion is also closely related to GIT and moduli theory. Odaka predicted that we can construct a moduli space (K-moduli) by using K-stability and Xu et. al. constructed K-moduli theory for log Fano pairs with an ample CM line bundle, which is a line bundle canonically defined. However, Odaka’s K-moduli conjecture is still open for general polarized varieties. In this talk, we introduce uniform adiabatic K-stability for Calabi-Yau fibrations, that is a uniform notion of K-stability when the polarization is very close to the base line bundle, and we construct K-moduli theory of Calabi-Yau fibrations over curves. Moreover, we will construct K-moduli theory for log Fano quasimaps and apply it to the quasi-projectivity for K-moduli of Calabi-Yau fibrations.</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_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. Irene De Blasi  (University of Turin)</div><div class="event_title">Billiards with Keplerian potential: refractive and reflective case  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A new type of billiard system, of interest for Celestial Mechanics, is taken into consideration: here, a closed refraction interface separates two regions in which different potentials (harmonic and Keplerian) act. This model, which can be studied both in two and three dimensions, presents strong analogies with the more studied Kepler billiard, where a Keplerian inner potential is associated with a reflecting wall. The seminar aims to provide results on the two models, ranging from the existence of periodic and quasi-periodic orbits to the characterization of integrable and non-integrable boundaries.Joint work with Vivina Barutello and Susanna Terracini. </div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/mathicse/">Computational Science and Engineering </a></div><br /><div class="event_speaker"> Jörg Nick (ETH Zürich)</div><div class="event_title">Regularized dynamical parametric approximation for stiff evolution problems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Evolutionary deep neural networks have emerged as a rapidly growing field of research. This talkdiscusses numerical integrators for such and other classes of nonlinear parametrizations u(t) = &#934;(&#952;(t)) wherethe evolving parameters &#952;(t) are to be computed. The primary focus is on tackling the challenges posedby the combination of stiff evolution problems and irregular parametrizations, which typically arise withneural networks, tensor networks, flocks of evolving Gaussians, and in further cases of overparametrization.Regularized parametric versions of classical time stepping schemes for the time integration of the parametersin nonlinear approximations to evolutionary partial differential equations are presented. At each time step,an ill-conditioned nonlinear optimization problem is solved approximately with a few regularized Gauß–Newton iterations. Error bounds for the resulting parametric integrator are shown. Numerical experimentsthat are designed to show key properties of the proposed parametric integrators are discussed.</div><div class="event_time">16:15 &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://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/zurich-colloquium-in-mathematics">Zurich Colloquium in Mathematics</a></div><br /><div class="event_speaker"> Nalini Anantharaman (Université de Strasbourg)</div><div class="event_title">Chaos and the spectral theory of hyperbolic surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The main question in quantum chaos is to relate the chaotic properties of a dynamical system (like a billiard in a bounded domain, or the geodesic flow on a closed manifold) to the spectral properties of the corresponding Schrödinger operator in quantum mechanics (the laplacian, in the examples above). This is usually asked for a given dynamical system, but one may try to make the problem more tractable by studying a "random" billiard, or the geodesic flow on a "random manifold". Several years ago, I became interested in the ergodic and spectral properties of random hyperbolic surfaces, in the asymptotic regime where the area of the surface goes to infinity. I will survey the existing techniques and some of the results.</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, May 21      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Shahar Mendelson</div><div class="event_title">Do we really need the Rademacher complexities? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The sample complexity of learning in a convex class and with respect to the squared loss is arguably the most important question in Statistical Learning Theory. The state-of-the-art estimates in this setting rely on Rademacher complexities, and those are generally difficult to control. I will explain why (contrary to prevailing belief) and under minimal assumptions, the Rademacher complexities are not really needed: the sample complexity is actually governed by the behaviour of the limiting gaussian process. In particular, all such learning problems that have the same L_2 structure - even those with heavy-tailed distributions - share the same sample complexity as if the problem were light-tailed. At the heart of the proof is the construction of uniform mean estimation procedures for some natural function classes. I will show how such uniform mean estimation procedures can be derived by combining optimal mean estimation techniques for real-valued random variables with Talagrand\'s generic chaining method.</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room F 26.1</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/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_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">Andrey Gogolyev (-)</div><div class="event_title">Rigidity of partially hyperbolic skew products <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This is joint work with Jon DeWitt. We study skew products over area-preserving Anosov diffeomorphisms on T^2×G, where G is a compact Lie group, given by (x,g)?(f(x),h(x)·g). We establish smooth rigidity; that is, if two such skew products are C^0 conjugate, then they are smoothly conjugate, unless h:T^2->G is cohomologous to a constant and the skew product is, in fact, a product with a translation on G. Interestingly, on twisted principal G-bundles, our approach gives exception-free rigidity.</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room E 33.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Qile Chen (Boston College)</div><div class="event_title">The tropical geometry of logarithmic Gauged Linear Sigma Models <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />How does counting curves in a complete intersection relate to the geometry of the ambient space? In this talk, I will introduce a tropical decomposition formula as an explicit answer to this Quantum Lefschetz type problem in the Gromov-Witten setting. More precisely, the tropical decomposition formula shows that Gromov-Witten of complete intersections can be approximated using ambient data, with correction terms given by virtual counts of (generalized) special linear series. The tropical decomposition formula is derived from studying the boundary structures of logarithmic Gauged Linear Sigma Models. This is a joint work in progress with Felix Janda and Yongbin Ruan. </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"> Stefano Modena (GSSI L\'Aquila)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-stefano-modena-gssi-laquila/">On some typicality and density results for non smooth vector fields</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />For the linear continuity equation associated to incompressible vector fields we show that the set of vector fields in $L^q_x$, $q&lt;\\infty$, for which the continuity equation admits a unique distributional solution in $L^{q\'}_x$ (for all initial data) is generic in the Baire category sense, whereas its complement, as well as some particular subset of it, is dense. Analog results for the ODE associated to continuous vector fields will be also discussed. (Joint work with Francesco Cianfrocca).</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"> Paula Truöl (MPIM Bonn)</div><div class="event_title">Non-complex cobordisms between quasipositive knots <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Quasipositive knots occur in complex geometry as transverse intersections of smooth algebraic curves in the complex plane &#8450;<sup>2</sup> with the 3-sphere. A complex cobordism is a surface that arises as a transverse intersection of a smooth algebraic curve with the region bounded between two 4-balls of different radius with common center in &#8450;<sup>2</sup>. The two knots bounded by a complex cobordism are necessarily quasipositive, and such a cobordism is necessarily optimal (defined in the talk). Feller asked whether these two necessary conditions for the existence of a complex cobordism between two knots are sufficient. In a joint work with Maciej Borodzik we answer this in the negative for cobordisms of any genus <i>g</i> &ge; 0. In the case of genus <i>g</i> = 0, we improve our result to strongly quasipositive knots.In the talk, we will define the relevant terms and provide some context for our results.</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"> Yves  Lejan  (Université Paris-Saclay)</div><div class="event_title">Loops, trees and fields on complete graphs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />After introducing the relations between spanning trees, random loops and bosonic/fermionic fields on general graphs, we focus on the case of the complete graph and derive a few asymptotics as its size increases to infinity.</div><div class="event_time">16:00 &bull; EPF Lausanne, CM1 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/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Dr. Allen Fang (Universität Münster)</div><div class="event_title">Wave behavior in the vanishing cosmological constant limit <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Black hole stability is a central topic in mathematical relativity that has seen numerous advancements in recent years. Both the Kerr-de Sitter and the Kerr black hole spacetimes have been proven to be stable in the slowly-rotating regime. However, the methods used have been markedly different, as well as the decay rates proven. Perturbations of Kerr-de Sitter converge exponentially back to a nearby Kerr-de Sitter black hole, while perturbations of Kerr only converge polynomially back to the family. In this talk, I will speak about wave behavior that is uniform in the cosmological constant by considering solutions to the Teukolsky equations in Kerr(-de Sitter). The main point is a careful handling of the relevant estimates on the region of the spacetime far from the black hole. This provides a first step into understanding the uniform (in the cosmological constant) stability of black hole spacetimes. This is joint work with Jeremie Szeftel and Arthur Touati.</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/sam/news-and-events/zhacm-colloquia">Zurich Colloquium in Applied and Computational Mathematics</a></div><br /><div class="event_speaker">Dr. Martin Halla (Karlsruhe Inst. of Technology)</div><div class="event_title">On the redundancy of regularity splittings for wavenumber explicit hp-FEM analysis <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 that finite element approximations of the Helmholtz equation suffer from thepollution effect for large wavenumbers k>0. This degeneracy can be avoided by the applicationof high order FEMs, with polynomial degree p chosen proportional to log k. The key ingredientof the respective analysis [1] is a so-called regularity splitting, which decomposes the solutionof the Helmholtz equation with a L^2 right hand-side into an analytical part and k-well behavedH^2 part. The generalization of this technique for nonconstant coefficients and other boundaryconditions is technical and nontrivial, but has received much attention lately. In this talk I showhow the classical Schatz technique can be adapted to circumvent the necessity of any regularitysplitting, which significantly simplifies the analysis. In the second part of the talk I discuss theapplication of this approach to heterogeneous media and Maxwell-impedance problems.[1] M. Melenk and S. Sauter, Convergence analysis for finite element discretizations ofthe Helmholtz equation with Dirichlet-to-Neumann boundary conditions, Math. Comp.,79(272):1871–1914, 2010.</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. Justin Salez (Université Paris-Dauphine & PSL)</div><div class="event_title">An invitation to the cutoff phenomenon <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The cutoff phenomenon is an abrupt transition from out of equilibrium to equilibrium undergone by certain Markov processes in the limit where the size of the state space tends to infinity. Discovered four decades ago in the context of card shuffling, this surprising phenomenon has since then been observed in a variety of models, from random walks on groups or complex networks to interacting particle systems. It is now believed to be universal among fast-mixing high-dimensional processes. Yet, current proofs are heavily model-dependent, and identifying the general conditions that trigger a cutoff remains one of the biggest challenges in the quantitative analysis of finite Markov chains. In this talk, I will provide a self-contained introduction to this fascinating question, and then describe a recent partial answer based on entropy and curvature. Joint work with Francesco Pedrotti.</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, May 22      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker"> Rares-Darius Buhai (ETH Zurich)</div><div class="event_title">The Quasi-Polynomial Low-Degree Conjecture is False <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />There is a growing body of work on proving hardness results for average-case optimization problems by bounding the low-degree likelihood ratio (LDLR) between a null distribution and a related planted distribution.Such hardness results are now ubiquitous not only for foundational average-case problems but also central questions in statistics and cryptography.This line of work is supported by the low-degree conjecture of Hopkins [Hop18], which in its extended form postulates that a vanishing degree-D LDLR implies the absence of any noise-tolerant distinguishing algorithm with runtime n^{D / polylog(D)} whenever (1) the null distribution is product and (2) the planted distribution is permutation invariant.We disprove this conjecture. Specifically, we show that for all sufficiently small &#949; > 0, there is a planted distribution on {0, 1}^{n(n-1)/2} that has a vanishing degree-n^{1-O(&#949;)} LDLR with respect to the uniform distribution on {0, 1}^{n(n-1)/2} even as an n^{O(log n)}-time algorithm solves the corresponding &#949;-noisy distinguishing problem. Our construction relies on algorithms for list-decoding for noisy polynomial interpolation in the high-error regime.Joint work with Jun-Ting Hsieh, Aayush Jain, and Pravesh Kothari.</div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room F 26.1</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"> Andrea di Lorenzo (Pisa)</div><div class="event_title">Compactifying the stack of maps from smooth curves to a quotient stack <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 way of compactifying the moduli stack of maps from smooth curves to a quotient stack, when the latter has a projective good moduli space and a properly stable point. One application of this result is the construction of certain moduli of fibered log Calabi-Yau pairs. This is a joint work with Giovanni Inchiostro.</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_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"> Jiaheng Chen (University of Chicago, US)</div><div class="event_title">Sharp concentration of simple random tensors <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Tensors are fundamental objects in mathematics, physics, statistics, and computer science, and they play an important role in a wide range of applied sciences and engineering disciplines. In this talk, we will focus on concentration inequalities for simple random tensors. We establish sharp dimension-free concentration inequalities and expectation bounds for the deviation of the sum of simple random tensors from its expectation. As part of our analysis, we use generic chaining techniques to obtain a sharp high-probability upper bound on the suprema of multi-product empirical processes. In so doing, we generalize classical results for quadratic and product empirical processes to higher-order settings.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room F 26.1</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/talks-in-financial-and-insurance-mathematics">Talks in Financial and Insurance Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Carole Bernard (Vrije Universiteit Brussel)</div><div class="event_title">Risk Sharing under Ambiguity <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The distribution of future losses related, for example, to climate risk is typically not perfectly known and is subject to ambiguity. In this context, we investigate how to design an optimal sharing scheme among agents (insurers, reinsurers, countries). We first derive the optimal risk-sharing arrangement under mean-variance preferences, considering distributional ambiguity of the aggregate risk to be shared. It is shown that proportional risk-sharing is always optimal and that the presence of ambiguity does not affect the structure of the risk-sharing arrangement, making it robust to such uncertainty. Desirable properties of risk sharing under ambiguity are discussed and several generalizations are also explored. Risk sharing under distortion risk measures will also be discussed. This is joint work with Steven Vanduffel.</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, May 23      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ne"><a class="external" href="https://unine.ch">Université de Neuchâtel</a></div><div class="event_type"><a class="external" href="https://www.unine.ch/math/home/colloques_et_seminaires/seminaires-de-linstitut.html">Séminaire de Géométrie et Systèmes dynamiques </a></div><br /><div class="event_speaker"> Stefan Matijevic (Universität Bochum)</div><div class="event_title">Positive (S1-equivariant) symplectic homology of convex domains, higher capacities, and Clarke\'s duality <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We prove that the filtered positive (S1-equivariant) symplectic homology of a convex domain is naturally isomorphic to the filtered singular (S1-equivariant) homology induced by Clarke\'s dual functional associated with the convex domain. As a result, we prove that the Gutt-Hutchings capacities coincide with the spectral invariants introduced by Ekeland-Hofer for convex domains. From this identification, it follows that Besse convex domains can be characterized by their Gutt–Hutchings capacities, which encode their type. This implies that the interiors of Besse-type convex domains carry information about the Reeb flow on their boundaries. In particular, we show that if the interior of a convex body is symplectomorphic to that of a rational ellipsoid, then the convex body must be Besse of the same type as the rational ellipsoid. Additionally, as a corollary of the aforementioned isomorphism, we deduce that the barcode entropy associated with the singular homology induced by Clarke\'s dual functional provides a lower bound for the topological entropy of the Reeb flow on the boundary of a convex domain in R^{2n}. In particular, this barcode entropy coincides with the topological entropy for convex domains in R^4.</div><div class="event_time">10:00 &bull; Université de Neuchâtel, Rue Emile-Argand 11, Room B217</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/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_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"> Ulrich Haböck (Starkware)</div><div class="event_title">Laurent STARKs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />"STARKs over circle curve unlock efficient proofs over Mersenne primes, i.e. primes of the form p = 2^n - 1. We demonstrate that the RC-STARK from [https://eprint.iacr.org/2024/1620] can be framed as yet another STARK over the circle curve, using Laurent polynomials in the quadratic extension of the Mersenne field (the Gaussian integers mod p)  as a univariate representation of circle polynomials. Moreover, Laurent encoding can be also performed by the circle FFT, letting the Laurent STARK achieve the same ``native\'\' performance as a circle STARK [https://eprint.iacr.org/2024/278]</div><div class="event_time">11:00 &bull; EPF Lausanne, BC420</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"> Yifan  Hu  (EPFL)</div><div class="event_title">Landscape of Policy Optimization for Finite Horizon MDPs with General State and Action <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Policy gradient methods are widely used in reinforcement learning. Yet, the nonconvexity of policy optimization imposes significant challenges in understanding the global convergence of policy gradient methods. For a class of finite-horizon Markov Decision Processes (MDPs) with general state and action spaces, we develop a framework that provides a set of easily verifiable assumptions to ensure the Kurdyka-&#321;ojasiewicz (K&#321;) condition of the policy optimization. Leveraging the K&#321; condition, policy gradient methods converge to the globally optimal policy with a non-asymptomatic rate despite nonconvexity. Our results find applications in various control and operations models, including entropy-regularized tabular MDPs, Linear Quadratic Regulator (LQR) problems, stochastic inventory models, and stochastic cash balance problems, for which we show an &#1013;-optimal policy can be obtained using a sample size in O(&#1013;-1) and polynomial in terms of the planning horizon by stochastic policy gradient methods. Our result establishes the first sample complexity for multi-period inventory systems with Markov-modulated demands and stochastic cash balance problems in the literature.</div><div class="event_time">13:30 &bull; EPF Lausanne, MA C1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ne"><a class="external" href="https://unine.ch">Université de Neuchâtel</a></div><div class="event_type"><a class="external" href="https://www.unine.ch/math/home/colloques_et_seminaires/seminaires-de-linstitut.html">Séminaire de Géométrie et Systèmes dynamiques </a></div><br /><div class="event_speaker"> Stefan Matijeciv (Universität Bochum)</div><div class="event_title">Systolic S1-index and characterization of non-smooth Zoll convex bodies <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />: We define the systolic S1-index of a convex body as the Fadell-Rabinowitz index of the space of centralized generalized systoles associated with its boundary. We show that this index is a symplectic invariant. Using the systolic S1-index, we propose a definition of generalized Zoll convex bodies and prove that this definition is equivalent to the usual one in the smooth setting. Moreover, we show how generalized Zoll convex bodies can be characterized in terms of their Gutt-Hutchings capacities and we prove that the space of generalized Zoll convex bodies is closed in the space of all convex bodies. As a corollary, we establish that if the interior of a convex body is symplectomorphic to the interior of a ball, then such a convex body must be generalized Zoll, and in particular Zoll if its boundary is smooth. Finally, we discuss some non-smooth examples that highlight the distinction between the smooth and non-smooth settings. In particular, we present a non-smooth example in which the systoles pass through every point on the boundary, yet the domain is not generalized Zoll. We also provide an example of a generalized Zoll convex body in which the systole passes through every boundary point.</div><div class="event_time">14:00 &bull; Université de Neuchâtel, Rue Emile-Argand 11, Room B217</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. Mariusz  Mirek (Rutgers University)</div><div class="event_title">The multilinear circle method and its consequences in pointwise ergodic theory <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Bergelson conjecture from 1996 asserts that the multilinearpolynomial ergodic averages with commuting transformations convergepointwise almost everywhere in any measure-preserving system. Thisproblem was recently solved affirmatively for polynomials with distinctdegrees. In this talk, I will review the recent progress on thisconjecture, focusing on the multilinear circle method --- a versatilenew tool that combines methods from additive combinatorics and Fourieranalysis, which are crucial in problems of this kind. This is based onjoint work with D. Kosz, S. Peluse and J. Wright.</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_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"> David  Chiron  (Université Côte d’Azur, Nice – France)</div><div class="event_title">On the Gross-Clark model for an impurity in a Bose-Einstein condensate <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Gross-Clark model is a coupled system describing the interaction of a particle in a Bose-Einstein condensate. We will look at stationary solutions (existence and numerical approximation) in dimensions 1 to 3. We will then look at traveling waves for this model, from the theoretical point of view by minimization under two constraints, and from the numerical point of view, based on stationary solutions.        This work stems from Joe Alhelou\'s thesis, co-supervised with M. Maris (Toulouse).</div><div class="event_time">14:15 &bull; EPF Lausanne, MA A1 12</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/schools/sb/research/math/statistics-seminars/">Statistics Seminar </a></div><br /><div class="event_speaker"> Heather Battey (Imperial College)</div><div class="event_title">Title T.B.A.</div><div class="event_time">15:15 &bull; EPF Lausanne, CM 1 517</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>';