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. 3</span>      <span style="float: right; text-align:right; width: 250px;">3.3 - 7.3.2025</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2025</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, March 3      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde">Bernoullis Tafelrunde</a></div><br /><div class="event_speaker"> Giacomo Cozzi (Università di Padova)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde/detail/bernoullis-tafelrunde-giacomo-cozzi-universita-di-padova/">Bernoulli Introduces Gradient Flows of Nonlocal Energies</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The aim of this talk is to present the theory of gradient flows on metric space. Given a functional defined on a Hilbert space, its gradient flow is the curve minimizing the functional in the fastest way possible, namely, following the opposite direction of its gradient. Starting from the pioneristic work of De Giorgi, it became possible to give a meaning to gradient flows even in spaces where the definition of gradient is not natural (i.e., on spaces which are not Hilbert). An important application is the case of gradient flows defined on the space of probability measures endowed with the Wasserstein distance. Using this theory, we will discuss two examples in which the functionals to be minimized are nonlocal (namely, long range interaction) energies. abstract</div><div class="event_time">12:15 &bull; Universität Basel</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/symplectic-geometry-seminar">Symplectic Geometry Seminar</a></div><br /><div class="event_speaker"> Felix Schlenk (Neuchâtel University)</div><div class="event_title">Singular polarizations of open symplectic 4-manifolds, with applications <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Twenty five years ago, Paul Biran introduced polarizations of closed symplectic manifoldsand showed that their Lagrangian skeleta exhibit remarkable rigidity properties.He in particular found that their complements contain only small balls.I will introduce similar polarizations of certain open 4-dimensional symplectic manifolds.This leads to several symplectic embedding results,that in turn lead to new Lagrangian non-removable intersectionsand a novel phenomenon of Legendrian barriers. For instance, given any connected symplectic 4-manifold $(M,\\omega)$and a 4-ball of smaller volume, their exists an explicit finite union of Lagrangiandiscs in the 4-ball such that their complement symplectically embeds into~$(M,\\omega)$,extending a result by Sackel--Song--Varolgunes--Zhu and Brendel.Other applications are new Lagrangian intersection results and relative versions of the Arnold chord conjecture.The talk will be non-technical and focus on the geometric constructions. This is joint work with Emmanuel Opshtein.</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">Prof. Dr. Kawanoue Hiraku (Kyoto University)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">The exponential function in characteristic p</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In characteristic $0$, Fuchs-Frobenius theory gives a description of a local solution of a Fuchsian differential equation at origin.  F. Fuernsinn and H. Hauser proved the analogous assertion in characteristic $p$, by using the formal variables $z_1, z_2,\\dots$ which satisfy $z_1\'=1/x$ and $z_{i+1}\'=z_i\'/z_i$ for $i \\geq1$.  We consider the exponential function in characteristic $p$, that is, the solution of $y=y\'$ with $y(0)=1$.  Note that the solution of a linear differential equation has a huge ambiguity by multiplying $p$-th power elements. Thus we have several choices for the expressions.In this talk, I will present a beautiful expression of the exponential function, which is quite structured. I also present the generalization of this observation to any linear differential equations of order $1$ in characteristic $p$. This is a joint work with F. Fuernsinn and H. Hauser. The main reference is \'\'On Abel\'s Problem about logarithmic Integrals in positive characteristic\'\' (arXiv:2401.14154).</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Room B6</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, March 4      </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"> Stéphane  Gaubert  (INRIA and CMAP, Ecole Polytechnique)</div><div class="event_title">The competitive spectral radius of families of nonexpansive mappings <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider a new class of repeated zero-sum games in which the payoff is the escape rate of a switched dynamical system, where at every stage, the transition is given by a nonexpansive operator depending on the actions of both players. This generalizes to the two-player (and non-linear) case the notion of joint spectral radius of a family of invertible matrices. We show that the value of this game does exist, and we characterize it in terms of an infinite dimensional non-linear eigenproblem. This provides a two-player analogue of Mañe’s lemma from ergodic control. This also extends to the two-player case results of Kohlberg and Neyman (1981), Karlsson (2001), and Vigeral and the author, concerning the asymptotic behavior of nonexpansive mappings (generalizations of the Wolff-Denjoy theorem). We also show that the value of the game admits a dual characterization when the nonexpansive maps are quasi-isometries, or when they are order preserving and positively homogeneous self-maps of a cone equipped with Funk’s and Thompson’s metrics.This is based on joint work with Marianne Akian and Loic Marchesini,arXiv:2410.21097</div><div class="event_time">10:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.unil.ch/dsa/en/home/menuinst/seminaires--evenements/research-seminars.html">Talks in Actuarial Mathematics </a></div><br /><div class="event_speaker"> Antoine  Usseglio Carleve  (University of Avignon)</div><div class="event_title">Accurate inference about extreme expectiles and Expected Shortfall <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The expectile and Expected Shortfall are prime candidates for being standard risk measures in actuarial and financial contexts, for their ability to recover information about probabilities and typical behavior of extreme values, as well as their axiomatic properties. A series of recent papers has focused on their estimation at extreme levels and has obtained the asymptotic normality of the proposed estimators. The obtention of accurate confidence intervals for extreme expectiles and Expected Shortfall is paramount in any decision process in which they are involved, but actual inference on these tail risk measures is still a difficult question due to their sensitivity to tail heaviness. This talk focuses on asymptotic Gaussian inference about tail expectiles in the challenging context of heavy-tailed observations, and tail Expected Shortfall in the general max-domain of attraction. We use an in-depth analysis of the proofs of asymptotic normality results to derive bias-reduced and variance-corrected Gaussian confidence intervals. We illustrate the usefulness of our construction on several sets of financial and insurance claims data.</div><div class="event_time">14:00 &bull; EPF Lausanne, Extranef 125</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/annonces/seminaire-danalyse-numerique">Séminaire d\'Analyse Numérique </a></div><br /><div class="event_speaker"> Andrey  Pilipenko (UNIGE)</div><div class="event_title">Diffusions in a media with semipermeable membranes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Diffusions in a medium with semipermeable membranes naturally arise in models of material science, chemistry, biology, telecommunications, etc.  We will discuss them from the following points of view: (a) macroscopic, (b) stochastic, (c) PDE.</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/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Matthias Christandl (Copenhagen)</div><div class="event_title">Asymptotic tensor rank is characterized by polynomials <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Asymptotic tensor rank is notoriously difficult to determine. Indeed, determining its value for the 2×2 matrix multiplication tensor would determine the matrix multiplication exponent, a long-standing open problem. On the other hand, Strassen\'s asymptotic rank conjecture makes the bold claim that asymptotic tensor rank equals the largest dimension of the tensor and is thus as easy to compute as matrix rank. Despite tremendous interest, much is still unknown about the structural and computational properties of asymptotic rank; for instance whether it is computable.We prove that asymptotic tensor rank is "computable from above", that is, for any real number r there is an (efficient) algorithm that determines, given a tensor T, if the asymptotic tensor rank of T is at most r. The algorithm has a simple structure; it consists of evaluating a finite list of polynomials on the tensor. Indeed, we prove that the sublevel sets of asymptotic rank are Zariski-closed (just like matrix rank). While we do not exhibit these polynomials explicitly, their mere existence has strong implications on the structure of asymptotic rank.As one such implication, we find that the values that asymptotic tensor rank takes, on all tensors, is a well-ordered set. In other words, any non-increasing sequence of asymptotic ranks stabilizes ("discreteness from above"). In particular, for the matrix multiplication exponent (which is an asymptotic rank) there is no sequence of exponents of bilinear maps that approximates it arbitrarily closely from above without being eventually constant. In other words, any upper bound on the matrix multiplication exponent that is close enough, will "snap" to it. Previously such discreteness results were only known for finite field or for other tensor parameters (e.g., asymptotic slice rank). We obtain them for infinite fields like the complex numbers.</div><div class="event_time">15:00 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_dis"><a class="external" href="https://unidistance.ch">UniDistance Suisse</a></div><div class="event_type"><a class="external_nolink">Number Theory Seminar</a></div><br /><div class="event_speaker"> Marco  Baracchini  (Università di Genova)</div><div class="event_title">BGG decomposition of some de Rham complexes over flag varieties <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The aim of this talk is to describe how BGG theory can be used to compute the de Rham cohomology over flag varieties. As motivational example we will see the GL_2-case computing the finite slope part of the de Rham cohomology of the sheaf \\mathbb{W}_k built in Andreatta-Iovita, interpolating the symmetric powers of the de Rham cohomology of the universal elliptic curve. Let G be a reductive group with a parabolic subgroup P, let g:=Lie(G) and V a finite-dimensional, irreducible g-module. Using BGG theory, we obtain a decomposition of the Koszul complex associated with V. Moreover we can construct a de Rham complex linked to the dual of V and the induced g-action. Faltings and Faltings-Chai discovered a relation between the Koszul and de Rham complexes, investigating how the BGG decomposition can be translated into a decomposition of the de Rham complex, ultimately enabling the computation of de Rham cohomology.</div><div class="event_time">15:00 &bull; <a class="external" href="fernuni.zoom.us/my/davidloeffler">UniDistance Suisse, online</a></div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker">Dr. Mitchell Taylor (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">Stable phase retrieval in function spaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A subspace $E \\subset L2(\\mu)$ is said to do stable phase retrieval (SPR) if there exists a constant $C \\geq 1$ such that for any $f,g \\in E$ we have$\\inf_{|| \\lambda || =1} || f- \\lambda g || \\leq C ||  |f| - |g|  ||$  In this case, if |f| is known, then f is uniquely determined up to an unavoidable global phase factor$\\lambda$ moreover, the phase recovery map is C-Lipschitz. Phase retrieval appears in several applied circumstances, ranging from crystallography to quantum mechanics. In this talk, I will present some elementary examples of subspaces of L2(µ) which do stable phase retrieval and discuss the structure of this class of subspaces. The material in this talk is based on joint work with M. Christ and B. Pineau as well as with D. Freeman, T. Oikhberg and B. Pineau.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://sites.google.com/view/agms-fribourg-seminars/home">Seminar Analysis and geometry on metric spaces</a></div><br /><div class="event_speaker"> Susanna Heikkilä (University of Jyväskylä)</div><div class="event_title">De Rham algebras of closed quasiregularly elliptic manifolds are Euclidean <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 discuss a result stating that, if a closed manifold admits a non-constant quasiregular map from a Euclidean space, then the de Rham cohomology of the manifold embeds into the Euclidean exterior algebra as a subalgebra. This embedding of algebras yields a topological classification of closed simply connected orientable 4-manifolds admitting a non-constant quasiregular map from the four-dimensional Euclidean space. The talk is based on joint work with Pekka Pankka (University of Helsinki).</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"> Thomas Coolican Fraser (Copenhagen)</div><div class="event_title">Eigenvalues of tetrahedral sums of Hermitian matrices <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Horn\'s problem aims to determine set of possible eigenvalues (a,b,c) for a triple of n x n Hermitian matrices (A,B,C) satisfying A+B=C. This talk is based on joint work with A. Alekseev and M. Christandl concerning a generalization of Horn\'s problem called the tetrahedral Horn problem. The tetrahedral Horn problem aims to determine the set of possible eigenvalues (a,b,c,d,e,f) for a sextuplet of n x n Hermitian matrices (A,B,C,D,E,F) satisfying A+B=C, B+D=F, C+D=E, and A+F=E. We will derive the complete solution for the tetrahedral Horn problem for n=2 and see how, unlike Horn\'s original problem, the solution space is neither convex nor a polytope.For general n, we describe various inequality conditions and symmetries of the tetrahedral Horn problem, as well as prove how the set of tetrahedral eigenvalues is characterized by the asymptotics of the Wigner 6j symbol for the unitary group U(n), generalizing the well-known correspondence between the Littlewood-Richardson coefficients and Horn\'s original problem.</div><div class="event_time">16:10 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat075.1">Zurich Graduate Colloquium</a></div><br /><div class="event_speaker">Stefano Galanda (Dipartimento di matematica - DIMA, Universita di Genova)</div><div class="event_title">What is... Algebraic Quantum Field Theory? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Algebraic approach to quantum theories was developed in the end of last century in order to provide a solid mathematical description to the theory of the standard model of particle physics and especially its generalization on curved spacetime backgrounds. Despite its original purpose, the formalism also emerged as a suitable framework for formulating the thermodynamic limit of models in statistical mechanics. The goal of this talk is to provide a gentle introduction to the algebraic approach by first presenting its main motivations and then outlining some of its mathematical foundations. In particular, we will present this approach as an abstract generalization of the mathematical framework of Quantum Mechanics.</div><div class="event_time">16:30 &bull; UZH Zentrum, Building KO2, Room F 150</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, March 5      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Adam Kanigowski (University of Maryland)</div><div class="event_title">Sparse Equidistribution Problems in Dynamics</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Dr. Marc Abboud (Université de Neuchâtel)</div><div class="event_title">Unlikely intersections problem for automorphisms of Markov surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The family of Markov surfaces M_D is a family of cubic affine surfaces parametrised by the complex line (here D is the parameter) that is related to the character variety of the punctured torus. It has sparked a lot of work in algebraic geometry, algebraic differential equations and low-dimensional topology. The mapping class group of the punctured torus acts on the character variety and preserves this family. Its image is a finite index subgroup of the group of automorphisms of M_D for every parameter D. We show the following result: for certain algebraic parameters D if two automorphisms of M_D with positive entropy share a Zariski dense set of periodic points then they share a common iterate. The proof uses tools from arithmetic dynamics such as the arithmetic equidistribution theorem of Yuan and Zhang and tools from quasi-Fuchsian representation theory.</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Rahul Pandharipande (ETH Zürich)</div><div class="event_title">The homomorphism question for A_g <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will discuss some ideas, results, and conjectures related to the following question: is projectionfor cycle on the moduli space of abelian varieties a homomorphism.</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_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"> Hiroshi  Kawabi  (Keio University / University of Oxford)</div><div class="event_title">A graph discretized approximation of diffusions with drift and killing on a complete Riemannian manifold <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> In this talk, we present a graph discretized approximation scheme for diffusions with drift and killing on a complete Riemannian manifold M. More precisely, for a given Schrödinger operator with drift on M having the form A = &#8722;&#916; &#8722; b + V , we introduce a family of discrete time random walks in the flow generated by the drift b with killing on a sequence of proximity graphs, which are constructed by partitions cutting M into small pieces. As a main result, we prove that the drifted Schrödinger semigroup {e&#8722;tA}t&#8805;0 is approximated by discrete semigroups generated by the family of random walks with a suitable scale change. This result gives a finite dimensional summation approximation of a Feynman-Kac type functional integral over M. Furthermore, when M is compact, we also obtain a quantitative error estimate of the convergence. This talk is based on a joint work with Satoshi Ishiwata (Yamagata University).</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://math.ethz.ch/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Prof. Dr. Erich Baur (Berner Fachhochschule, Technik und Informatik)</div><div class="event_title">Graduate Workshop Reinforcement</div><div class="event_time">17:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room  H12</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, March 6      </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/colloque">Colloque de Mathématiques </a></div><br /><div class="event_speaker"> Nicolas Monod (EPFL)</div><div class="event_title">Geometry, groups and fixed points <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In the infinite diversity of geometric spaces, some landscapes are very familiar and accessible: Euclidean spaces, hyperbolic geometry, tree-like objects. These and many more can be related to matrix groups by studying their symmetries.Meanwhile, in abstract harmonic analysis, there is also a class of very accessible groups: those where some form of Fourier analysis is possible, for instance abelian groups.We will discuss an analogy between these two topics; it relies on a fundamental fixed-point principle.</div><div class="event_time">16:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Dr. Victor Navarro-Fernández (Department of Mathematics, Imperial College London)</div><div class="event_title">Exponential mixing with random cellular flows via hypocoercivity <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study a passive scalar equation on a two-dimensional periodic box, where the advecting velocity field is given by a cellular flow with a randomly moving center. We prove that the passive scalar undergoes mixing at an exponential rate, independent of any underlying diffusivity. Furthermore, we show that the velocity field enhances dissipation, and we establish sharp decay rates that, for large times, are deterministic and remain uniform in the diffusivity constant. Our approach is purely Eulerian and relies on a suitable modification of Villani&#039;s hypocoercivity method. This is a joint project with C. Seis (Universität Münster).</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_dis"><a class="external" href="https://unidistance.ch">UniDistance Suisse</a></div><div class="event_type"><a class="external" href="https://distanceuniversity.ch/academic-events/mathematics-colloquium/">Mathematics Colloquium </a></div><br /><div class="event_speaker"> Sobhan  Seyfaddini  (ETH Zürich)</div><div class="event_title">Area-preserving transformations and symplectic geometry <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In an influential article from the 1970s, Albert Fathi, having proven that the group of compactly supported volume-preserving homeomorphisms of the n-ball is simple for n &#8805; 3, asked if the same statement holds in dimension 2. In a joint work with Cristofaro-Gardiner and Humiliére, we proved that the group of compactly supported area-preserving homeomorphisms of the 2-disc is not simple. This answers Fathi\'s question and settles what is known as the simplicity conjecture in the affirmative.  We will discuss Fathi’s problem and its solution.</div><div class="event_time">17:00 &bull; <a class="external" href="fernuni.zoom.us/j/64850280617">UniDistance Suisse, online</a></div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-financial-and-insurance-mathematics">Talks in Financial and Insurance Mathematics</a></div><br /><div class="event_speaker">Dr. Aleksei Minabutdinov (ETH Zurich)</div><div class="event_title">Transversality Condition Matters: Ensuring Uniqueness of  Deep Learning Solutions in Economics and Finance <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Transversality is an important sufficient condition for identifying the solution in infinite horizon economic and financial models. Without such a condition, there exists a continuum of functions that satisfy the Hamilton-Jacobi-Bellman (HJB) functional equation. In this paper, we explore this manifold of solutions with numerical and analytical methods. Using a standard continuous-time model, we demonstrate that, without explicitly imposing the transversality condition, widely used numerical algorithms, including the (Deep) Galerkin-type methods, may converge to arbitrary points of this manifold, leading to significant and uncontrollable biases. Using an example of the AK-Ramsey model with logarithmic utility (a prototypical model for many financial mathematics and macro/environmental economics applications), the paper demonstrates that the area of direct applicability of projection-type algorithms is narrower than one might expect based on contemporary literature. We propose a novel approach using a functional transformation of the original HJB equation to effectively incorporate the transversality condition, ensuring convergence to the actual value function.</div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, March 7      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Boris Bukh (Carnegie Mellon University)</div><div class="event_title">Discrete Geometry</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.unil.ch/dsa/en/home/menuinst/seminaires--evenements/research-seminars.html">Talks in Actuarial Mathematics </a></div><br /><div class="event_speaker"> François  Bachoc  (University of Toulouse)</div><div class="event_title">Gaussian processes with inequality constraints: theory and computation</div><div class="event_time">11:00 &bull; EPF Lausanne, Extranef 125</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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">Dr. Seoyoung Kim (UBasel)</div><div class="event_title">Certain families of K3 surfaces and their modularity <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We start with a double sextic family of K3 surfaces with fourparameters with Picard number $16$. Then by geometric reduction(specializing at fiber) processes, we obtain three, two and oneparameter families of K3 surfaces of Picard number $17, 18$ and $19$respectively. All these families turn out to be of hypergeometric typein the sense that their Picard-Fuchs differential equations are given byhypergeometric or Heun functions. We will study the geometry of2-parameter families and related finite hypergeometric series in detail.We will then discuss some relevant modularity questions. This is a jointwork with A. Clingher, A. Malmendier, and N. Yui.</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/schools/sb/research/math/statistics-seminars/">Statistics Seminar </a></div><br /><div class="event_speaker"> Daniel  Nevo (Tel Aviv University)</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 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. Michele Graffeo (SISSA)</div><div class="event_title">The motive of the Hilbert scheme of points <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Hilbert scheme of points on a quasi-projective variety is a classical object in algebraic geometry. However, its geometry is  nowadays still not completely accessible. On the other hand, the motive of a variety X is an invariant attached to X carrying a lot of information about its geometry, and it is considered as a universal Euler characteristic. In a joint project with  Monavari, Moschetti and Ricolfi we give general formulas to compute the motive of the Hilbert scheme of points, provided the knowledge of a finite amount of data (that we gave explicitly in some cases). In my seminar I will present our formulas and I will show many applications.</div><div class="event_time">16:00 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sfs/news-and-events/data-science-seminar">ETH-FDS seminar </a></div><br /><div class="event_speaker"> David M. Blei (Columbia University)</div><div class="event_title">Joint talk ETH-FDS Seminar - Research Seminar on Statistics: "Hierarchical Causal Models" <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Analyzing nested data with hierarchical models is a staple of Bayesian statistics, but causal modeling remains largely focused on "flat" models. In this talk, we will explore how to think about nested data in causal models, and we will consider the advantages of nested data over aggregate data (such as data means) for causal inference. We show that disaggregating your data---replacing a flat causal model with a hierarchical causal model---can provide new opportunities foridentification and estimation. As examples, we will study how toidentify and estimate causal effects under unmeasured confounders, interference, and instruments.Preprint: https://arxiv.org/abs/2401.05330This is joint work with Eli Weinstein.</div><div class="event_time">16:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room D 7.2</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://stat.ethz.ch/events/research_seminar">Research Seminar in Statistics</a></div><br /><div class="event_speaker"> David M. Blei (Columbia University)</div><div class="event_title">Joint talk ETH-FDS Seminar - Research Seminar on Statistics:"Hierarchical Causal Models" <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Analyzing nested data with hierarchical models is a staple of Bayesian statistics, but causal modeling remains largely focused on "flat" models. In this talk, we will explore how to think about nested data in causal models, and we will consider the advantages of nested data over aggregate data (such as data means) for causal inference. We show that disaggregating your data---replacing a flat causal model with a hierarchical causal model---can provide new opportunities foridentification and estimation. As examples, we will study how toidentify and estimate causal effects under unmeasured confounders, interference, and instruments.Preprint: https://arxiv.org/abs/2401.05330This is joint work with Eli Weinstein.</div><div class="event_time">16:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room D 7.2</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>';