var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-76"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-74"><img src="//www2.math.ethz.ch/smsjs/images/arrow_right.png"/></a></div>    <div class="sms_title">      <span style="float: left;">SMS</span>      <span>SWISS MATHEMATICAL SOCIETY</span>      <span style="float: right;">SMG</span>    </div>    <div class="sms_info">      <span style="float: left; width: 250px;">Bulletin no. 6</span>      <span style="float: right; text-align:right; width: 250px;">23.10 - 27.10.2023</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Autumn Semester 2023</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, October 23      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-mathematical-physics">Talks in Mathematical Physics</a></div><br /><div class="event_speaker"> Ryan Grady (Montana State University)</div><div class="event_title">Black Hole Entropy via Observables <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />https://www.math.uzh.ch/mat074</div><div class="event_time">13:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/tggroup/doku.php?id=fables">Séminaire "Fables Géométriques" </a></div><br /><div class="event_speaker"> Antoine Toussant (Genève)</div><div class="event_title">Real Structures of Phase Tropical Surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Phase tropical surfaces can appear as a limit of a 1-parameter family of smooth complex algebraic surfaces. A phase tropical surface admits a stratified fibration over a smooth tropical surface. We study the real structures compatible with this fibration and give a description in terms of tropical cohomology. As an application, we deduce combinatorial criteria for the type of a real structure of a phase tropical surface. Time permitting, we will also discuss the connection with Renaudineau and Shaw\'s spectral sequence and Kalinin\'s spectral sequence.</div><div class="event_time">15:00 &bull; Université de Genève, salle 6 - 13</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/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Dr. Daniele Galli (Universität Zürich)</div><div class="event_title">A cohomological approach to Ruelle-Pollicott resonances of Anosov diffeomorphisms <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Given a transitive Anosov diffeomorphism on a closed connected manifold, it is known that, for enough smooth observables, the system is mixing w.r.t. the measure of maximal entropy. Accordingly, it makes sense to investigate the speed of decay of correlations and to look for the so-called Ruelle-Pollicott resonances, in order to determine an asymptotic for the correlation limit. In this talk I will describe some recent ideas to tackle these questions. In particular, I will point out some surprising connections between the spectrum of a particular transfer operator acting on suitable Anisotropic Banach spaces of currents and the spectrum of the action induced by the Anosov map on the De Rham cohomology. As a corollary, we obtain an upper bound for the speed of mixing. This talk is based on my PhD thesis that I defended last June at the University of Bologna.</div><div class="event_time">15:00 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Pazit Haim Kislev (Tel-Aviv University)</div><div class="event_title">Symplectic Barriers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In his seminal 2001 paper, Biran introduced the concept of *LagrangianBarriers*, a symplectic rigidity phenomenon coming from obligatoryintersections with Lagrangian submanifolds which don\'t come from meretopology.In this joint work with Richard Hind and Yaron Ostrover, we present whatappears to be the first illustration of *Symplectic Barriers, *a formof symplecticrigidity stemming from  necessary intersections of symplectic embeddingswith symplectic submanifolds (and in particular not Lagrangian). In ourwork, we also tackle a question by Sackel–Song–Varolgunes–Zhu and providebounds on the capacity of the ball after removing a codimension 2hyperplane with a prescribed Kähler angle.</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>    </div>    <div class="day">      <div class="day_title">        Tuesday, October 24      </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"> George Willis (University of Newcastle, Australia)</div><div class="event_title">Self-replicating groups and scale groups <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Self-replicating groups are isometry groups of rooted trees which furnish important examples of groups in geometric and combinatorial group theory. Scale groups are isometry groups of regular trees which arise as subquotients of general totally disconnected, locally compact (t.d.l.c.) groups. It will be explained how these classes of groups are essentially equivalent despite acting on different types of trees. This equivalence allows an exchange of ideas between the study of discrete groups on one hand and t.d.l.c. groups on the other. In particular, the role of scale groups in the structure theory of general t.d.l.c. groups raises general questions about the structure of scale groups.</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_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">Dr. Daria Tieplova (ICTP, Trieste)</div><div class="event_title">Fundamental limits of overparametrized shallow neural networks for supervised learning <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will discuss the joint work done with Francesco Camilli and JeanBarbier concerning an information-theoretical analysis of a two-layerneural network trained from input-output pairs generated by a teachernetwork with matching architecture, in overparametrized regimes. Ourresults come in the form of bounds relating i) the mutual informationbetween training data and network weights, or ii) the Bayes-optimalgeneralization error, to the same quantities but for a simpler(generalized) linear model for which explicit expressions are rigorouslyknown. Our bounds, which are expressed in terms of the number of trainingsamples, input dimension and number of hidden units, thus yieldfundamental performance limits for any neural network (and actually anylearning procedure) trained from limited data generated according to ourtwo-layer teacher neural network model. The proof relies on rigorous toolsfrom spin glasses and is guided by ``Gaussian equivalence principles\'\'lying at the core of numerous recent analyses of neural networks. Withrespect to the existing literature, which is either non-rigorous orrestricted to the case of the learning of the readout weights only, ourresults are information-theoretic (i.e. are not specific to any learningalgorithm) and, importantly, cover a setting where all the networkparameters are trained.</div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://calendar.google.com/calendar/embed?mode=AGENDA&height=600&wkst=2&bgcolor=%23FFFFFF&src=t36it03v52cus2detrvinlgk18%40group.calendar.google.com&color=%235F6B02&ctz=Europe%2FZurich">Groups, Arithmetic and Algebraic Geometry Seminar </a></div><br /><div class="event_speaker"> Dimitriy Rumynin (Warwick)</div><div class="event_title">C_2 graded groups, their real representations and Dyson\'s tenfold way <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> A C_2 graded group is a pair, a group G and an index two subgroup H. A "real representation" of G is a complex representation of H together with a given (to be chosen) action of the outer coset G\\H.  Different choices lead to different theories.Such representations appear independently in three different disciplines : Algebra, Physics and Topology. The goal of the talk is to review the formalism and various choices, including resulting theories.  The talk is based upon recent work of the speaker and James Taylor (Oxford) and Matthew B. Young (Utah State).</div><div class="event_time">15:15 &bull; EPF Lausanne</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker">Dr. Mitchell Taylor (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">Low regularity well-posedness for the general quasilinear Schrödinger equation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We present a new and relatively simple method for proving large data  local well-posedness in low regularity Sobolev spaces for  general quasilinear Schrödinger equations of the form \\begin{equation*}\\begin{cases}&i\\partial_tu+g^{jk}(u,\\overline{u},\\nabla u,\\nabla\\overline{u})\\partial_j\\partial_k u=F(u,\\overline{u},\\nabla u,\\nabla\\overline{u}),\\hspace{5mm} u:\\mathbb{R}\\times\\mathbb{R}^d\\to\\mathbb{C}^m,\\\\&u(0,x)=u_0(x),\\end{cases}\\end{equation*}assuming only non-degeneracy of the metric, nontrapping and  mild regularity/decay of the initial data. As a consequence, we  remove the uniform ellipticity assumption from the main result of Marzuola, Metcalfe and Tataru (Arch. Ration. Mech. Anal. 2021) and substantially weaken the regularity/decay assumptions  from the pioneering works of Kenig, Ponce, Rolvung and Vega.This is based on joint work with Ben Pineau (UC Berkeley).</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/zurich-colloquium-in-mathematics">Zurich Colloquium in Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Peter Hintz (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">Perturbations and weak interactions of black holes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Following a brief introduction to general relativity and the Einstein field equations, I will discuss two interrelated recent developments in the mathematical study of black holes and some of the mathematical techniques involved. In the first part, I describe the stability properties of various exact black hole solutions under regular small perturbations, namely the relaxation of an out-of-equilibrium black hole to a stationary state; this has been the subject of intense recent activity by a number of research groups, and is now understood in a fair amount of detail. In the second part, I will discuss work in progress towards the construction of singular perturbations of spacetimes via the insertion of small black holes: this aims to provide the first rigorous examples of spacetimes describing the merger of two black holes with extreme mass ratios. </div><div class="event_time">16:30 &bull; UZH Zentrum, Building KO, Room F 150</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="http://www.unine.ch/math/home/colloques_et_seminaires/les-colloques-du-mardi.html">Colloque du Mardi </a></div><br /><div class="event_speaker"> Adélie Garin (EPFL)</div><div class="event_title">When TDA meets geometric group theory: A stratification of barcode space using Coxeter complexes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />At the intersection of data science and algebraic topology, topological data analysis (TDA) is a recent field of study that provides robust mathematical, statistical and algorithmic methods for analysing the topology and geometry underlying complex data. TDA has proven useful in many applications, including biology, materials science and climate science, and continues to evolve rapidly. Barcodes are frequently used invariants in TDA. They provide topological summaries of the persistent homology of a filtered space. Understanding the structure and geometry of the barcode space is therefore crucial for applications. In this talk, we use Coxeter complexes to define new coordinates on the barcode space. These coordinates define a stratification of the barcode space with n bars, where the highest dimensional strata are indexed by the elements of the symmetric group. This creates a bridge between the fields of TDA, geometric group theory and permutation statistics, which could be exploited by researchers in each field.This presentation is based on joint work with B. Brück. No prerequisites on TDA or Coxeter complexes are required.</div><div class="event_time">17:00 &bull; Université de Neuchâtel, Institut de Mathématiques, B103</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, October 25      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne </a></div><div class="event_type"><a class="external" href="https://calendar.google.com/calendar/embed?mode=AGENDA&height=600&wkst=2&bgcolor=%23FFFFFF&src=t36it03v52cus2detrvinlgk18%40group.calendar.google.com&color=%235F6B02&ctz=Europe%2FZurich">Groups, Arithmetic and Algebraic Geometry Seminar </a></div><br /><div class="event_speaker"> Dinakar Ramakrishnan (Caltech)</div><div class="event_title">Title T.B.A.</div><div class="event_time">10:00 &bull; EPF Lausanne </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"> Matt Koster (Toronto)</div><div class="event_title">The topology of moduli spaces of flat connections. <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We start by introducing the moduli space of flat connections on a principal PSL(2;R)-bundle P over a closed orientable surface of genus g>1. We will then describe some results on the topology of the moduli space, as well as some conjectures.</div><div class="event_time">10:15 &bull; Université de Genève, Section de mathématiques, 7-9 rue du Conseil-Général, Room 1-07</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://commonweb.unifr.ch/_Science/Math/Pub/Math/seminars/OSgeom-top.html">Oberseminar Geometrie</a></div><br /><div class="event_speaker"> Nicola Cavalucchi (EPFL)</div><div class="event_title">Convergence of CAT(0) groups and spaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We describe the possible limits of uniformly cocompact CAT(0)-group actions with a particular interest on the collapsing case. As an application we show a corollary on the finiteness of such groups. If there is enough time we will see how totally disconnected, unimodular groups enter naturally in the discussion.</div><div class="event_time">10:20 &bull; Université de Fribourg, 1.309 PER07</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"> Ce Ji (Beijing Univ. and ETH Zürich)</div><div class="event_title">Toward a generalization of the Witten conjecture from spectral curve <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Over decades of development of the Witten conjecture, Many enumerative geometries are related to integrable hierarchies. Simultaneously, such theories can also be reconstructed from topological recursion, an algorithm producing multi-differential forms from the underlying spectral curve. In this talk, we propose a generalization of the Witten conjecture from spectral curve, which produce descendent potential functions for corresponding enumerative geometry related to certain reductions of (multi-component) KP hierarchy. Proof for genus zero spectral curve with one boundary will be sketched, which can be applied to deduce the rKdV integrability of deformed negative r-spin theory, conjectured by Chidambaram--Garcia-Falide--Giacchetto.</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_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"> Stefanie Zbinden (Heriot-Watt)</div><div class="event_title"> From strong contraction to hyperbolicity  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />For almost 10 years, it has been known that if a group contains a strongly contracting element, then it is acylindrically hyperbolic. Moreover, one can use the Projection Complex of Bestvina, Bromberg and Fujiwara to construct a hyperbolic space where said element acts WPD. For a long time, the following question remained unanswered: if Morse is equivalent to strongly contracting, does there exist a space where all generalized loxodromics act WPD? In this talk, I will present a construction of a hyperbolic space, that answers this question positively.</div><div class="event_time">15:45 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sam/news-and-events/zhacm-colloquia">Zurich Colloquium in Applied and Computational Mathematics</a></div><br /><div class="event_speaker">Prof. Dr. Gianluca Crippa (Departement Mathmatik und Informatik, Universität Basel)</div><div class="event_title">Anomalous dissipation in fluid dynamics <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Kolmogorov\'s K41 theory of fully developed turbulence advances quantitative predictions on anomalous dissipation in incompressible fluids: although smooth solutions of the Euler equations conserve the energy, in a turbulent regime information is transferred to small scales and dissipation can happen even without the effect of viscosity, and it is rather due to the limited regularity of the solutions. In rigorous mathematical terms, however, very little is known. In a recent work in collaboration with M.~Colombo and M.~Sorella we consider the case of passive-scalar advection, where anomalous dissipation is predicted by the Obukhov-Corrsin theory of scalar turbulence. In my talk, I will present the general context and illustrate the main ideas behind our construction of a velocity field and a passive scalar exhibiting anomalous dissipation in the supercritical Obukhov-Corrsin regularity regime. I will also describe how the same techniques provide an example of lack of selection for passive-scalar advection under vanishing diffusivity, and an example of anomalous dissipation for the forced Euler equations in the supercritical Onsager regularity regime (this last result has been obtained in collaboration with E.~Bru\\`e, M.~Colombo, C.~De Lellis, and M.~Sorella).</div><div class="event_time">16:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room E 1.2</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. Nathanael Berestycki (University of Vienna)</div><div class="event_title">Weyl law in Liouville quantum gravity <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Can you hear the shape of Liouville quantum gravity (LQG)?We obtain a Weyl law for the eigenvalues of Liouville Brownian motion: the n-th eigenvalue grows linearly with n, with the proportionality constant given by the Liouville measure of the domain and a certain deterministic constant which is computed explicitly and is, surprisingly, strictly greater than its Riemannian counterpart. Afterexplaining this result and its context, as well as some related estimates pertaining to the small-time behaviour of the heat kernel, I hope to also present a number of conjectures on the spectral geometryof LQG.These relate both to the behaviour of eigenfunctions (suggestingintriguing connections with so-called "quantum chaos") and to that of eigenvalues, for which we conjecture a connection to random matrixstatistics.This is joint work with Mo-Dick Wong (Durham).</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, October 26      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Javier Fresán (Sorbonne Université)</div><div class="event_title">E-functions and 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_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/~palmeran/topsem.html">Séminaire de Topologie et Géométrie </a></div><br /><div class="event_speaker"> Jessica Liu (Toronto)</div><div class="event_title">On Kashaev\'s conjecture for signatures of links <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> The Levine-Tristram signature of a link is a classical invariant with many definitions and applications. It is closely related to the Alexander polynomial and its roots, provides lower bounds on topological invariants such as slice and doubly slice genus, and is nearly-everywhere a concordance invariant. In 2018 Kashaev introduced a link invariant defined using a simple algorithm on link diagrams, which he conjectured to be twice the Levine-Tristram signature. The case of definite knots, i.e. those with maximal signature, was proved by Cimasoni and Ferretti by relating Kashaev\'s invariant to the Kauffman model of the Alexander polynomial and using the Gordon-Litherland description of signature. We describe a way to obtain Kashaev\'s invariant using the original Seifert surface definition of the Levine-Tristram signature, establishing Kashaev\'s conjecture for general links.</div><div class="event_time">12:00 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Philip Engel</div><div class="event_title">Title T.B.A.</div><div class="event_time">14:00 &bull; EPF Lausanne </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/zahlentheorie/">Seminar Zahlentheorie</a></div><br /><div class="event_speaker"> Yuri Bilu (Université de Bordeaux)</div><div class="event_title">Skolem meets Schanuel <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A linear recurrence of order~r over a number field~K is a map U:&#8484;&#8594;K satisfying a relation of the formU(n+r)=ar&#8722;1U(n+r&#8722;1)+&#8943;+a0U(n)(n&#8712;&#8484;),where a0,…,ar&#8722;1&#8712;K and a0&#8800;0. A linear recurrence is called simple if the characteristic polynomial Xr&#8722;ar&#8722;1Xr&#8722;1&#8722;…&#8722;a0 has only simple roots, and non-degenerate if &#955;/&#955;&#8242; is not a root of unity for any two distinct roots &#955;,&#955;&#8242; of the characteristic polynomial. The classical Theorem of Skolem-Mahler-Lech asserts that a non-degenerate linear recurrence may have at most finitely many zeros. However, all known proofs of this theorem are non-effective and do not produce any tool to determine the zeros.In this talk I will describe a simple algorithm that, when terminates, produces the rigorously certified list of zeros of a given simple linear recurrence. This algorithm always terminates subject to two celebrated conjectures: the p-adic Schanuel Conjecture, and the Exponential Local-Global Principle. We do not give any complexity bound (even conditional to some conjectures), but the algorithm performs well in practice, and was implemented in the Skolem tool   https://skolem.mpi-sws.org/that I will demonstrate.A joint work with Florian Luca, Joris Nieuwveld, Joël Ouaknine, David Purser andJames Worrell.</div><div class="event_time">14:15 &bull; Universität Basel, Spiegelgasse 1, SR 00.003</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/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Dr. Michele Dolce (EPFL)</div><div class="event_title">Stability threshold of the 2D Couette flow in a homogeneous magnetic field <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A planar incompressible and electrically conducting fluid can be described by the 2D Navier-Stokes-MHD system. One simple yet physically relevant laminar state is the Couette flow with a constant homogeneous magnetic field, given by \\(u_E=(y,0)\\), \\(B_E=(b,0)\\) in the domain \\(\\mathbb{T}\\times\\mathbb{R}\\). The goal is to estimate how large can be a perturbation of this state while still resulting in a solution close to the laminar regime, thereby preventing the onset of turbulence. We prove that Sobolev regular initial perturbations of size \\(O(Re^{-2/3})\\), with Re being the Reynolds number, remain close to \\(u_E, B_E\\) and exhibit dissipation enhancement. The latter quantifies the convergence towards an x-independent state on a time-scale \\(O(Re^{-1/3})\\), much faster than the standard diffusive one \\(O(Re^{-1})\\).</div><div class="event_time">16:15 &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_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"> Helmut Harbrecht (University of Basel)</div><div class="event_title">Talk by Helmut Harbrecht <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Shape optimization is indispensable for designing and constructing industrial components. Many problems that arise in application, particularly in structural mechanics and in the optimal control of distributed parameter systems, can be formulated as the minimization of functionals which are defined over a class of admissible domains.The application of gradient based minimization algorithms involves the shape functionals\' derivative with respect to the domain under consideration. Such derivatives can analytically be computed by means of shape calculus and enable the paradigm first optimize then discretize. Especially, by identifying the sought domain with a parametrization of its boundary, the solution of the shape optimization problem is equivalent to solving a nonlinear pseudodifferential equation for the unknown parametrization.The present talk aims at surveying on analytical and numerical methods for shape optimization. In particular, besides several applications of shape optimization, the following items will be addressed:- first and second order optimality conditions;- discretization of shapes; - existence and convergence of approximate shapes;- efficient numerical techniques to solve shape optimization problems.</div><div class="event_time">17:00 &bull; UniDistance Suisse, online</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. Ying Chen (National University of Singapore)</div><div class="event_title">Optimal Market Making under Model Uncertainty: A Robust Reinforcement Learning Approach <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study the optimal market making problem in order-driven electronic markets, with a focus on model uncertainty. We consider ambiguity in order arrival intensities and derive a robust strategy that can perform under various market conditions. To achieve this, we introduce a tractable model for the limit order book using Markov Decision Processes and develop robust Reinforcement Learning to solve the complex optimization problem. This approach enables us to accurately represent the order book dynamics with tick structures, as opposed to the usual price dynamics modeled in stochastic approaches. This is a joint work with Hoang Hai Tran, Julian Sester and Yijiong Zhang.</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, October 27      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/seminar-in-numerical-analysis">Seminar in Numerical Analysis</a></div><br /><div class="event_speaker"> Carsten Gräser (FAU Erlangen-Nürnberg)</div><div class="event_title">PDE-regularized learning <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the regularization of a supervised learning problem by partial differential equations (PDEs). For the resulting regularized problem we derive error bounds in terms of a PDE error term and a data error term. These error contributionsquantify the accuracy of the PDE model used for regularization and the data coverage.Furthermore, the discretization of the PDE-regularized learning problem by generalized Galerkin methods including finite elements and neural networks approaches is investigated. A nonlinear version of Céa\'s lemma allows to derive errors bounds for both classes of discretizations and gives first insights into error analysis of variational neural network discretizations of PDEs.</div><div class="event_time">11:00 &bull; Universität Basel, Spiegelgasse 5, Seminarraum 05.001</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"> Javier Fresán (Sorbonne Université )</div><div class="event_title">A construction of the polylogarithm motive <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Classical polylogarithms give rise to a variation of mixed Hodge-Tate structures on the projective line minus three points, which is an extension of the symmetric power of the Kummer variation by a trivial variation. By results of Beilinson-Deligne, Huber-Wildeshaus and Ayoub, this polylogarithm variation has a lift to the category of mixed Tate motives, whose existence is proved by computing the corresponding spaces of extensions both in the Hodge and the motivic settings. I will present a joint work with Clément Dupont, in which we construct the polylogarithm motive as an explicit, easy to remember, relative cohomology motive. </div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://stat.ethz.ch/events/zukost">ZueKoSt: Seminar on Applied Statistics</a></div><br /><div class="event_speaker"> Johanna Ziegel (University of Bern)</div><div class="event_title">Sequential alternatives to the t-test <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The (asymptotic) t-test is used in many situations. In order to ensure type-I-error guarantees, it is necessary to specify the sample size before the data collection process, and one cannot peek at the data before all data has arrived. However, looking at the data during the data collection process may happen (or may even be desirable). In such cases, a sequential alternative to the t-test is more appropriate since it controls type-I-error even when checking for significance after each new data point that has arrived. Three sequential alternatives to the t-test will be presented and compared in a simulation study. </div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</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>';