var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-42"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-40"><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;">2.10 - 6.10.2023</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 2      </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"> Nikita Markarian (Strasbourg)</div><div class="event_title"> Perturbative Chern-Simons invariants and factorization homology <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_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. Gabriela Estevez (Universidade Federal Fluminense)</div><div class="event_title">Some recent results on multicritical circle maps <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In 1984 Yoccoz proved that any two C^3 orientation-preserving circle homeomorphisms, with the same quantity of non-flat critical points and the same irrational rotation number, are topologically conjugated. For maps with only one critical point, it has been shown that the conjugacy is, in fact, a C^1-diffeomorphism. Moreover, in a total Lebesgue measure set of irrational rotation numbers the conjugacy can be improved to be C^{1+\\alpha}. In this talk, we will discuss some recent results concerning the smoothness of the conjugacy for maps with more than one critical point, and how these results are obtained using renormalization.</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/news-and-events/events/lecture-series/inaugural-and-farewell-lectures.html">Inaugural Lectures</a></div><br /><div class="event_speaker">Prof. Dr. Sarah Zerbes</div><div class="event_title">The mysteries of L-values</div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room F 30</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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. Lucas Slot (ETH)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Polynomial optimization and sums of squares</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Polynomial optimization is a recent field, which emerged in the last two decades. It deals with optimization problems whose objective and constraints are polynomials (POPs). These problems have diverse applications, e.g., in operations research, discrete geometry, optimalcontrol and theoretical computer science. However, they are computationally hard to solve exactly. Therefore, much attention has gone to finding tractable approximations for POPs.The most successful of these rely on results from real algebraic geometry dating back to the work of Hilbert. Namely, they use sums of squares to verify nonnegativity of polynomials. By increasing the maximum degree of the sums of squares involved, this yields a hierarchy of bounds on the global optimum of the original POP, called the SOS-hierarchy. At a fixed level, these bounds may be computed by solving a semidefinite program, making them tractable.Under mild conditions, the SOS-hierarchy converges asymptotically to the global optimum. A natural question is to understand the rate of this convergence, or equivalently, the quality of the approximations. In this talk, we discuss some recent advancements on this question in a variety of settings. We will use tools from real algebra, Fourier analysis and reproducing kernels.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Lecture Room B6</div>        </div>        <div class="day_content_item important"><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. Georg Oberdieck (KTH Stockholm)</div><div class="event_title">Curve counting on the Enriques surface and the Klemm-Marino formula <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />An Enriques surface is the quotient of a K3 surface by a fixed point-free involution. Klemm and Marino conjectured a formula expressing the Gromov-Witten invariants of the local Enriques surface in terms of automorphic forms. In particular, the generating series of elliptic curve counts on the Enriques should be the Fourier expansion of (a certain power of) Borcherds automorphic form on the moduli space of Enriques surfaces. In this talk I will explain a proof of this conjecture. The proof uses the geometry of the Enriques Calabi-Yau threefold in fiber classes. If time permits, I will also discuss various conjectures about non-fiber classes.</div><div class="event_time">17:30 &bull; Zoom</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, October 3      </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"> Laurent Bartoldi (Saarbruecken)</div><div class="event_title">Propriété (T) <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />La propriété (T) de Kazhdan s\'exprime, pour un groupe, en termes de sesreprésentations unitaires. Elle a toutefois de nombreuses conséquences etinterprétations qui n\'ont rien à voir avec les représentations unitaires. Jeparlerai un peu d\'applications : constructions de graphes expanseurs,génération de nombres aléatoires, et montrerai comment elle a été récemmentprouvée pour quelques exemples remarquables de groupes d\'automorphismes: automorphismes d\'un groupe libre de rang au moins quatre (avec l\'assistanced\'un ordinateur), ou automorphismes «modérés» d\'une algèbre universelle àau moins trois générateurs. Ce dernier exemple permet très facilement deprouver que les graphes de Cayley de groupes symétriques peuvent formerune famille de graphes expanseurs. Deux outils sont essentiels : uneinterprétation de (T) en termes de programmation linéaire et conique, et unenotion d\'«angle» entre sous-groupes d\'un groupe donné.C\'est en partie un travail en commun avec Martin Kassabov.</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_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"> Joscha Fregin (Technische Universität Hamburg)</div><div class="event_title">A Comparison of IMEX- Spectral Deferred Correction, Multistep and Runge-Kutta Methods for the rotating Shallow Water Equations  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Atmospheric motion covers a broad range of time- and spatial scales. Low and high pressure systems can influence us for days or even weeks and they extend up to hundreds of kilometers. In contrast, sound waves pass by in seconds with wavelengths of centimeters to meters. Implicit-explicit (IMEX) time stepping methods can help to avoid drastic limitations on the time step induced by the variety of scales without requiring computationally expensive fully nonlinear implicit solves.In our talk, we compare IMEX- Spectral Deferred Correction (SDC), multistep and Runge-Kutta time integrators for the Galewsky test case using the Python spectral method framework Dedalus. We demonstrate that SDC methods have superior stability properties and can provide shorter time to solution for comparable errors. In addition, we outline strategies that could further reduce simulation times by using the SDC residual to minimise the computational effort and by parallelising SDC "across the method". Finally, we discuss the interpretation of SDC as a Runge-Kutta method.</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_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"> Lorenzo Garcia (Université de Neuchâtel)</div><div class="event_title">Reduction of plane quartics and Cayley octads <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> In this talk I will give a conjectural characterization of the stable reduction of plane quartics over local fields in terms of their Cayley octads. This results in p-adic criteria that efficiently give the stable reduction type amongst either the 42 possible types in the general case or the 32 possible types when the reduction is hyperelliptic. These criteria are in the vein of the new machinery of “cluster pictures" for hyperelliptic curves. We will also construct explicit families of quartic curves that realise all possible stable types, against which we have tested these criteria. We will give many numerical examples that illustrate how to use these criteria in practice.This is a join work with RAYMOND VAN BOMMEL, JORDAN DOCKING, VLADIMIR DOKCHITSER and REYNALD LERCIER.</div><div class="event_time">15:00 &bull; Université de Neuchâtel, Institut de Mathématiques, B103</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"><a class="external" href="https://gabrielarpino.github.io/"> Gabriel Arpino (University of Cambridge)</a></div><div class="event_title">Statistical-Computational Tradeoffs in Mixed Sparse Linear Regression <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the problem of mixed sparse linear regression with two components, where two sparse signals are observed through n unlabelled noisy linear measurements. Prior work has shown that the problem suffers from a significant statistical-to-computational gap, resembling other computationally challenging high-dimensional inference problems such as Sparse PCA and Robust Sparse Mean Estimation. We establish the existence of a more extensive computational barrier for this problem through the method of low-degree polynomials, but show that the problem is computationally hard only in a very narrow symmetric parameter regime. We identify smooth information-computation tradeoffs in this problem and prove that a simple linear-time algorithm succeeds outside of the narrow hard regime. To the best of our knowledge, this is the first thorough study of the interplay between mixture symmetry, signal sparsity, and their joint impact on the computational hardness of mixed sparse linear regression. This is joint work with Ramji Venkataramanan. https://proceedings.mlr.press/v195/arpino23a.html.</div><div class="event_time">15:05 &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_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"> Richard Hain (Duke)</div><div class="event_title">Hodge correlators, the Goldman-Turaev Lie bialgebra and Johnson homomorphisms <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Goncharov\'s Hodge correlators give a method for computing the periods of the real mixed Hodge structure on the unipotent fundamental group of a hyperbolic Riemann surface X. The Hodge correlator of X takes values in the cyclic quotient of the graded Lie bialgebra |T(H_1(X)|. The goal of the talk is to explain how Goncharov\'s work is related to Johnson homomorphisms and the Goldman--Turaev Lie bialgebra.</div><div class="event_time">15:15 &bull; Université de Genève, Section de mathématiques, 7-9 rue du Conseil-Général, Room 1-07</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, October 4      </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"> Yalong Chen</div><div class="event_title">From curve counting on Calabi-Yau 4-folds to quasimaps for quivers with potentials  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will start by reviewing an old joint work with Davesh Maulik and Yukinobu Toda on relating Gromov-Witten, Gopakumar-Vafa (in the sense of Klemm-Pandharipande) and stable pair invariants on compact Calabi-Yau 4-folds. For non-compact CY4 like local curves, similar invariants can be studied via the perspective of quasimaps to quivers with potentials. In a recent joint work with Gufang Zhao, we define a virtual count for such quasimaps and prove a gluing formula. Computations of examples will also be discussed. </div><div class="event_time">10:00 &bull; EPF Lausanne, CM 1 104</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"> Giulio Belletti (Sorbonne)</div><div class="event_title">The volume conjecture and generalized hyperbolic polyhedra <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Broadly speaking, volume conjectures relate the asymptotic growth ofcertain quantum invariants of topological objects (manifolds, links, graphs) to the volume of some hyperbolic structure on the object. I willgive an overview of the topic without assuming any previous knowledgeof quantum invariants, and I will discuss how studying this conjecturenaturally leads to questions in hyperbolic geometry, especially as it pertains to the volume of hyperbolic polyhedra and to a more general notionof hyperbolic tetrahedron.</div><div class="event_time">10:20 &bull; Université de Fribourg, 0.05 PER23</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_default">Universit&auml;t Neuchatel</div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/aa/?events">Neuchatel - St.Gallen - Zurich Seminar in Coding Theory and Cryptography</a></div><br /><div class="event_speaker">Benjamin Jany (University of Kentucky)</div><div class="event_title">Bounds and Field size of Locally Recoverable Codes. <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In the last decade, Locally Recoverable Codes (LRC) have been a critical topic in communication and distributed storage. In addition, the minimum distance, dimension and length of a code LRCs also consider the locality of a code, i.e. the minimum number of entries needed to recover a given entry for any codeword. The parameters of LRCs are subject to a general Singleton bound and codes achieving the bound are called optimal LRCs. Constructions are known when the underlying field size of the code is larger than the length of the code. However, still little is known about the existence of optimal LRCs over small underlying field sizes. In this talk, I will show how we established new bounds that depend on locality and the field size of code using a duality theory of LRCs and the combinatorial structure of the code. This talk is based on joint work with A. Gruica and A. Ravagna</div><div class="event_time">15:00 &bull; Uni Neuchatel, E213</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. Wenjia Jing (Tsinghua University)</div><div class="event_title">Quantitative homogenization of elliptic problems in periodic high contrast environments <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider elliptic equations with periodic high contrast coefficients and study the asymptotic analysis when the periodicity is sent to zero and/or the contrast parameters are sent to extreme values. Those coefficients model small inclusions that have very different physical properties compared to the surrounding environment. Homogenization captures the macroscopic effects of those inclusions. We report some quantitative results such as the convergence rates of the homogenization (with proper correctors), uniform regularity for the solutions of the heterogeneous equations, and so on.  The talk is based on joint works with Mr. Xin Fu.</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. Igor Kortchemski (ETH Zürich)</div><div class="event_title">Global freezing</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 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"> Javier Fresán (École polytechnique, Palaiseau)</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_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"> Jean Lannes (Paris-Sorbonne)</div><div class="event_title">Sur l’application de Quillen pour la cohomologie modulo 2 de certains groupesfinis <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Soit G un groupe fini. Dans un célèbre article Quillen décrit en particulier un F-isomorphisme de F2-algèbres commutatives N-graduées                      qG : H&#8727;(G; F2) &#8594; L(G) ,  avec L(G) définie en termes des 2-groupes abéliens élémentaires contenus dans G. Nous montrerons que qG est en fait un isomorphisme pour trois familles de groupes finis : les groupes symétriques, les groupes alternés et les groupes de Coxeter finis.   </div><div class="event_time">14:00 &bull; EPF Lausanne, GA 3 21 - CIB EPFL</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"><a class="external" href="https://uol.de/marcus-christiansen">Prof. Dr. Marcus C. Christiansen (Universität Oldenburg)</a></div><div class="event_title">A journey through multi-state modelling in life insurance <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />What is the probabilistic core of life insurance modelling? What kind of mathematical objects are premiums and reserves? Which modelling assumptions are really necessary and which are not? The presentation will take the audience on a journey through old concepts and modern interpretations. Traditions will be challenged and alternative views presented.</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 6      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/anmath/seminars/">Seminar of Analysis </a></div><br /><div class="event_speaker"> Vikram Giri (Princeton)</div><div class="event_title">The Onsager Conjecture in 2D <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We will begin with a brief outline of the proof of the Onsager conjecture in 3 dimensions via the method of a Nash iteration. Along the way, we\'ll notice the difficulties in extending this to the case of 2 dimensions and we\'ll discuss how to overcome these via a linear Newton iteration. We will end with a discussion of possible future directions. This is joint work with R&#259;zvan-Octavian Radu.</div><div class="event_time">14:15 &bull; EPF Lausanne, MA B1 11</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"> Søren Wengel Mogensen (Lund University and the University of Copenhagen)</div><div class="event_title">Graphical models of local independence in stochastic processes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Graphs are often used as representations of conditional independence structures of random vectors. In stochastic processes, one may use graphs to represent so-called local independence. Local independence is an asymmetric notion of independence which describes how a system of stochastic processes (e.g., point processes or diffusions) evolves over time. Let A, B, and C be three subsets of the coordinate processes of the stochastic system. Intuitively speaking, B is locally independent of A given C if at every point in time knowing the past of both A and C is not more informative about the present of B than knowing the past of C only. Directed graphs can be used to describe the local independence structure of the stochastic processes using a separation criterion which is analogous to d-separation. In such a local independence graph, each node represents an entire coordinate process rather than a single random variable.In this talk, we will describe various properties of graphical models of local independence and then turn our attention to the case where the system is only partially observed, i.e., some coordinate processes are unobserved. In this case, one can use so-called directed mixed graphs to describe the local independence structure of the observed coordinate processes. Several directed mixed graphs may describe the same local independence model, and therefore it is of interest to characterize such equivalence classes of directed mixed graphs. It turns out that directed mixed graphs satisfy a certain maximality property which allows one to construct a simple graphical representation of an entire Markov equivalence class of marginalized local independence graphs. This is convenient as the equivalence class can be learned from data and its graphical representation concisely describes what underlying structure could have generated the observed local independencies.Deciding Markov equivalence of two directed mixed graphs is computationally hard, and we introduce a class of equivalence relations that are weaker than Markov equivalence, i.e., lead to larger equivalence classes. The weak equivalence classes enjoy many of the same properties as the Markov equivalence classes, and they provide a computationally feasible framework while retaining a clear interpretation. We discuss how this can be used for graphical modeling and causal structure learning based on local independence.</div><div class="event_time">15:15 &bull; EPF Lausanne, MA A3 31</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. Yalong Cao (RIKEN (Japan))</div><div class="event_title">Gopakumar-Vafa type invariants of holomorphic symplectic 4-folds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />BPS invariants were introduced by Gopakumar-Vafa on Calabi-Yau 3-folds, Klemm-Pandharipande on CY 4-folds and Pandharipande-Zinger on CY 5-folds. They are conjectured to be integers (proven in many cases) and have correspondence with Gromov-Witten invariants. On holomorphic symplectic 4-folds, (ordinary) GW and hence BPS invariants vanish, one can consider reduced GW invariants which are usually nontrivial rational numbers. In this talk, we will introduce BPS invariants for such a reduced theory. Joint works with Georg Oberdieck and Yukinobu Toda. </div><div class="event_time">16:00 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>  </div>  <div id="sms_footer">    address: Alessandra Naldi Windler, Departement Mathematik, HG G 51.4, ETH Zurich, Raemistrasse 101, CH-8092 Zurich<br />    email: <a href="mailto:bulletin@math.ch">bulletin@math.ch</a> | phone: +41 44 632 3684 | url: <a href="https://math.ch">https://math.ch</a>    <br /><br /><img src="//www2.math.ethz.ch/smsjs/sms_logo.gif" width="150" alt="SMS/SMG Logo" title="SMS/SMG Logo" />  </div></div>';