var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-15"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-13"><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. 8</span>      <span style="float: right; text-align:right; width: 250px;">8.4 - 12.4.2024</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2024</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, April 8      </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/cmgr/cmgr/geometry-seminar">Geometry Seminar</a></div><br /><div class="event_speaker"> Louis Merlin (CPEG A. Dumas, Paris)</div><div class="event_title"><a class="external" href="https://memento.epfl.ch/event/systolic-ratio-of-the-sphere-an-overview-geometr-2">Systolic Ratio of the sphere: an overview</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We first define the systolic ratio of the sphere in different contexts, from the most classical (a Riemannian sphere) to the most general (a contact flow on the sphere) and survey different problems and results related to this notion (among which: is it bounded? and if yes, what is the supremum?).Beside the survey part of this talk, one of the goals is to present a new construction of a systolically extremal (Finsler) metric on the sphere. This construction is motivated both by the systolic problem and by general considerations on desingularization techniques of Finsler metrics. This part of the talk is a work in progress with Guillaume Buro.</div><div class="event_time">11:00 &bull; EPF Lausanne, Room CM-1-517</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/studium/mathematik/doktorat/bernoullis-tafelrunde">Bernoullis Tafelrunde</a></div><br /><div class="event_speaker"> Christoph Brackenhofer (University of Freiburg)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde/detail/bernoullis-tafelrunde-christoph-brackenhofer-university-of-freiburg/">Periods and o-minimality</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Period numbers form a countable subset of the complex numbers. One can describe periods via a pairing between (algebraic) de Rham cohomology and singular cohomology or using semi-algebraic sets. A variant are exponential periods which admit similar descriptions, where singular cohomology is replaced by rapid decay cohomology and semi-algebraic sets are replaced by sets definable in a certain o-minimal structure. This talk will be an introduction to these ideas. abstract</div><div class="event_time">12:15 &bull; Universität Basel, Spiegelgasse 5, Seminar Room 05.002</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-mathematical-physics">Talks in Mathematical Physics</a></div><br /><div class="event_speaker"> Alexander Veselov (University of Loughborough)</div><div class="event_title">Burau representation and q-rationals <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Few years ago, Morier-Genoud and Ovsienko introduced a new interesting “quantisation” of the real numbers generalising the classical q-version of integers due to Euler and Gauss. I will explain a link between the corresponding q-deformed rational numbers and the classical Burau representation of the braid group B_3. This will be applied to the open problem of classification of faithful complex specializations of this representation. The talk is based on a joint work with Sophie Morier-Genoud and Valentin Ovsienko. </div><div class="event_time">13:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/tggroup/doku.php?id=fables">Séminaire "Fables Géométriques" </a></div><br /><div class="event_speaker"> Jules Chenal (Université de Lille)</div><div class="event_title">T-Hypersurfaces with a Maximal Number of Connected Components <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A T-hypersurface is a combinatorial hypersurface of the real locus of a projective toric variety Y . It is constructed from a primitive triangulation K of a moment polytope P of Y and a 0-cochain &#949; on K with coefficients in the field with two elements F2, called a sign distribution. O. Viro showed that when K is convex the T-hypersurface is ambiantly isotopic to a real algebraic hypersurface of Y . A. Renaudineau and K. Shaw gave upper bounds on the Betti numbers of T-hypersurfaces in terms of the Hodge numbers of a generic section of the ample line bundle L associated with the moment polytope. In particular, the number of connected components of a T-hypersurface cannot exceed the geometric genus of a generic section of L plus one. We want to present a generalisation of B. Haas\' theorem that characterises the couples (K;&#949;) leading to T- hypersurfaces realising the Renaudineau-Shaw upper bound on the number of connecte components. In contrast with the dimension 2 we find that the upper bound is not always attainable on every primitive triangulations. For some of those on which it is not attainable we provide a sharper upper bound. Finally we use our characterisation to show that there always exist a triangulation and a sign distribution on the standard simplex that reach the Renaudineau-Shaw upper bound. </div><div class="event_time">14:30 &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://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"> Sobhan Seyfaddini (University of Paris-Saclay)</div><div class="event_title">Asymptotics of link spectral invariants <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I’ll discuss the connection between (sub)leading asymptotics of the Floer theoretic link spectral invariants and the classical Calabi andRuelle invariants along with their connections to the algebraic structureof conservative homeomorphism groups.  Based on joint joint works withCristofaro-Gardiner, Humilière, Mak and Smith.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/mpseminar/seminar.html">Séminaire de Mathématique Physique </a></div><br /><div class="event_speaker"> Christoforos  Panagiotis (University of Bath)</div><div class="event_title">Random tangled currents and the continuity of the phase transition for $\\phi^4$ <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 an overview of my recent work on $\\varphi^4$ with Trishen Gunaratnam, Romain Panis and Franco Severo. I will describe the random tangled current representation and discuss how we used it to prove that the phase transition of the $\\varphi^4$ model is continuous in dimensions $d\\geq 3$, and to characterise the structure of translation invariant Gibbs measures. Along the way, I will mention some open problems and our ongoing work on the supercritical behaviour of $\\varphi^4$.</div><div class="event_time">16:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_be"><a class="external" href="https://www.unibe.ch">Universität Bern</a></div><div class="event_type"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Mathematisches Kolloquium </a></div><br /><div class="event_speaker">Dr. Gergely Kiss (Rényi Institute of Mathematics)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Recent progress on the Discrete Pompeiu problem on the plane</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We study the following discrete analogue of the integral geometric problem of Dimitrie Pompeiu.We say that a finite subset E of the Euclidean plane is Pompeiu, whenever for a given function f the values of f on any congruent copy of E is zero, then f is identically zero.Although for sets of two or three elements the affirmative answer is easy, until recently, even for four-point sets the answer was not known. Applying harmonic analysis in some varieties connected to the problem and also some results on linear equations of units we prove that every set having at most six elements is Pompieu, and every finite set consisting of algebraic numbers is Pompeiu.We also discuss the connections of this problem to some results in Euclidean Ramsey theory and the finite Steinhaus set problem posed by Stephen Jackson.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Lecture Room B6</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, April 9      </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://www.math.uzh.ch/mat770.1">Oberseminar: Algebraische Geometrie</a></div><br /><div class="event_speaker">Dr. David Urbanik (IHES)</div><div class="event_title">Arithmetic deformation of line bundles <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We introduce a new method to study mixed characteristic deformations of line bundles. In particular, given a sufficiently large family of smooth projective varieties defined over a ring of integers, we produce an explicit proper closed locus in the base outside of which all line bundles defined on positive characteristic fibres lift to a line bundle on a characteristic zero fibre. Joint work with Ziquan Yang.</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://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://inf.ethz.ch/people/people-atoz/person-detail.MjQzMzAz.TGlzdC8zMDQsLTIxNDE4MTU0NjA=.html"> Jingqiu Ding (ETH Zürich, CH)</a></div><div class="event_title">Private graphon estimation via sum-of-squares <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We develop the first pure node-differentially-private algorithms for learning stochastic blockmodels and for graphon estimation with polynomial running time for any constant number ofblocks. The statistical utility guarantees match those of the previous best information-theoretic(exponential-time) node-private mechanisms for these problems. The algorithm is based on anexponential mechanism for a score function defined in terms of a sum-of-squares relaxationwhose level depends on the number of blocks.The key ingredients of our results are (1) a characterization of the distance between the blockgraphons in terms of a quadratic optimization over the polytope of doubly stochastic matrices,(2) a general sum-of-squares convergence result for polynomial optimization over arbitrarypolytopes, and (3) a general approach to perform Lipschitz extensions of score functions as partof the sum-of-squares algorithmic paradigm.</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_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"><a class="external" href="https://math.ethz.ch/people/vgiri01">Dr. Vikramaditya Giri (ETH Z&uuml;rich, Switzerland)</a></div><div class="event_title">Spectral gaps for coclosed 1-forms on hyperbolic 3-manifolds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />For hyperbolic 3-manifolds we study two quantifications of theproperty of having vanishing first Betti number, one analytic and onetopological: the spectral gap for the Laplacian on coclosed 1-forms andthe size of the first torsion homology group. First we construct asequence of closed hyperbolic integer homology spheres with volumetending to infinity and a uniform coclosed 1-form spectral gap, whichanswers a question asked by Lin-Lipnowski in connection with theexistence of irreducible solutions to the Seiberg-Witten equations.Interestingly, the proof uses a topological property of the sequence inorder to deduce a uniform gap. We\'ll then explore the connection betweena sequence of 3-manifolds having such a uniform gap and exponential involume torsion homology growth. In the context of towers of arithmetic3-manifolds, such a connection was suggested by the work ofBergeron-&#350;engün-Venkatesh. We show that for any sequence of closedhyperbolic 3-manifolds with uniformly bounded rank, if it has a uniformcoclosed 1-form spectral gap, then it must have exponential torsionhomology growth.Based on joint work with Amina Abdurrahman, Anshul Adve, Ben Lowe, andJonathan Zung.</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://www.math.uzh.ch/mat075.1">Zurich Graduate Colloquium</a></div><br /><div class="event_speaker">Thomas Jacob (Universität Zürich)</div><div class="event_title">What is... a motive?</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, April 10      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Shahar Mendelson (Australian National University)</div><div class="event_title">Proof of the Majorizing Measure Theorem: Part I <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />As part of a mini-course hosted by the FIM, the speaker will give a complete proof of the Majorizing Measures Theorem (roughly 4h of lecture). In the occasion of the announcement of the awarding of the Abel prize to Michel Talagrand, the organisers suggested, and the speaker kindly agreed, to isolate this part of the course as a 4h event, where the proof (and some of the motivation) will be made accessible also to audience that is not attending the course. This will take place on 10.04.24 split in two two-hour sessions, one in the morning (10:15) and another in the afternoon (14:15), both at G43. All are welcome and we hope to see many of you there!</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_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"> Sofia Amontova (UniGE)</div><div class="event_title">Numerical invariants of representations of complex hyperbolic lattices <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Representations of fundamental groups of manifolds into PU(n, 1) havebeen studied from various viewpoints. In the context of higher Teich-müller theory, the so-called Toledo invariant in its different incarnationshas been most commonly employed to single out special classes of re-presentations of surface groups. In the extended setting of higher di-mensional non-compact complex hyperbolic manifolds of finite volume,other types of volume invariants prove to be useful. The talk aims topresent the volume invariant of representations using the machinery ofbounded cohomology and to prove an integrality result in the extendedsetting. Joint work with Michelle Bucher.</div><div class="event_time">10:20 &bull; Université de Fribourg, room Phys 2.52</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">Prof. Dr. Carlos Matheus Silva Santos (CNRS)</div><div class="event_title">Non-conical strictly convex divisible sets are maximally anisotropic <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Let U be a non-conical strictly convex divisible set. Even though the boundary S of U is not C^2, Benoist showed that S is C^1+ and Crampon established that S has a sort of anisotropic Holder regularity -- described by a list L of real numbers -- at almost all of its points. In this talk, we discuss our joint work with P. Foulon and P. Hubert showing that S is maximally anisotropic in the sense that the list L contains no repetitions thanks to the features of the Hilbert flow.</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_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/analysis/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker"> Roman Shvydkoy (University of Illinois at Chicago)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-roman-shvydkoy-university-of-illinois-at-chicago/">Volumetric approach to intermittency in fully developed turbulence</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The classical Kolmogorov-41 theory of turbulence is based on a set of  pivotal assumptions on scaling and energy dissipation for solutions satisfying incompressible fluid models. In the early 80\'s experimental evidence emerged that pointed to departure from the K41 predictions, which was attributed to the phenomenon of statistical intermittency.  In this talk we give an overview of the classical results in the subject, relationship of intermittency to the problem of global well-posedness of the 3D Navier-Stokes system, and discuss a new approach developed jointly with A. Cheskidov on how to measure and study intermittency from a rigorous perspective.  At the center of our discussion will be a new interpretation of an intermittent signal described by volumetric properties of the filtered field.  It provides, in particular, a systematic approach to the Frisch-Parisi multifractal formalism, and recasts intermittency from the point of view of information theory.</div><div class="event_time">14:15 &bull; Universität Basel, Spiegelgasse 5, Seminarraum 05.002</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Shahar Mendelson (Australian National University)</div><div class="event_title">Proof of the Majorizing Measure Theorem: Part II <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />As part of a mini-course hosted by the FIM, the speaker will give a complete proof of the Majorizing Measures Theorem (roughly 4h of lecture). In the occasion of the announcement of the awarding of the Abel prize to Michel Talagrand, the organisers suggested, and the speaker kindly agreed, to isolate this part of the course as a 4h event, where the proof (and some of the motivation) will be made accessible also to audience that is not attending the course. This will take place on 10.04.24 split in two two-hour sessions, one in the morning (10:15) and another in the afternoon (14:15), both at G43. All are welcome and we hope to see many of you there!</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://memento.epfl.ch/event/probability-and-stochastic-analysis-seminar/">Probability (and Stochastic Analysis) Seminar </a></div><br /><div class="event_speaker"> Jean-Dominique Deuschel (TU Berlin)</div><div class="event_title">An isomorphism theorem for anharmonic fields and scaling limits <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We introduce a natural measure on bi-infinite random walk trajectories evolving in a time-dependent environment driven by the Langevin dynamics associated to a gradient Gibbs measure with convex potential. We derive an identity relating the occupation times of the Poissonian cloud induced by this measure to the square of the corresponding gradient field, which is  generically not Gaussian. In the quadratic case, we recover a well-known generalization of the second Ray-Knight theorem. We further determine the scaling limits of the various objects involved in dimension 3, which are seen to exhibit homogenization. In particular, we prove that the renormalized square of the gradient field converges under appropriate rescaling to the Wick-ordered square of a Gaussian free field on R^3 with suitable diffusion matrix, thus extending a celebrated result of Naddaf and Spencer regarding the scaling limit of the field itself.</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://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sam/news-and-events/zhacm-colloquia">Zurich Colloquium in Applied and Computational Mathematics</a></div><br /><div class="event_speaker">Dr. Kaibo Hu (University of Edinburgh, UK)</div><div class="event_title">Towards Finite Element Tensor Calculus <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Finite Element Exterior Calculus (FEEC) provides a cohomology framework for structure-preserving discretisation of a large class of PDEs. Differential complexes are important tools in FEEC. The de Rham complex is a basic example, with applications in curl-div related problems such as the Maxwell equations. There is a canonical finite element discretisation of the de Rham complex, which in the lowest order case coincides with discrete differential forms (Whitney forms). Different problems involve different complexes.  In this talk, we provide an overview of some efforts towards Finite Element Tensor Calculus, inspired by tensor-valued problems from continuum mechanics and general relativity. On the continuous level, we systematically derive new complexes from the de Rham complexes. On the discrete level,  We review the idea of distributional finite elements, and use them to obtain analogies of the Whitney forms for these new complexes. A special case is Christiansen’s finite element interpretation of Regge calculus, a discrete geometric scheme for metric and curvature.</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://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Dr. Hugo Vanneuville (CNRS, Université Grenoble Alpes)</div><div class="event_title">Exponential decay for Bernoulli percolation via stochastic comparison <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Bernoulli percolation of parameter p on Z^d is defined by deleting each edge of Z^d with probability 1-p, independently of the other edges. The exponential decay theorem - proven in the 80\'s by Menshikov and, independently, by Aizenman and Barsky - can be stated as follows: If the cardinality of the cluster of 0 is a.s. finite at some parameter p, then it has an exponential moment at every parameter q&lt;p. I like to state this theorem this way because it illustrates the fact that decreasing p infinitesimally has a regularising effect on the percolation clusters. A new - shorter - proof has been proposed by Duminil-Copin and Tassion in 2016. The goal of this talk is to propose yet a new proof of this theorem, inspired by Russo\'s work from the early 80s, which relies on stochastic comparison techniques.</div><div class="event_time">17:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, April 11      </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/zahlentheorie/">Seminar Zahlentheorie</a></div><br /><div class="event_speaker">  </div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/rhine-seminar-on-transcendence-basel-freiburg-strasbourg/">Fifth Meeting</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />More information on the website: <a href="https://rhine-transcendence.github.io/meeting5" target="_blank">https://rhine-transcendence.github.io/meeting5</a></div><div class="event_time">09:30 &bull; Universität Basel, Kollegienhaus, Hörsaal 120</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Umut Çetin (London School of Economics)</div><div class="event_title">Mathematics of Market Microstructure</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"> François  Costantino </div><div class="event_title">Stated skein modules of 3-manifolds and TQFTs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />After reviewing the definition of stated skein modules for surfaces and 3 manifolds, I will detail how this recent notion allows to relate topological constructions (related to cut and paste techniques) to algebraic ones (braided tensor products of algebra objects in braided categories for instance). I will explain how the stated skein algebra of some special surfaces provides a topological description for some notable algebras (e.g. the quantised functions ring $O_q(\\mathfrak{sl_2})$ or its ``transmutation’’ BSL_2(q)). Then I will describe how stated skein moduli of 3-manifolds fit into a TQFT framework albeit a non completely standard one. If time permits I will also discuss some unexpected non injectivity results in dimension 3. (Joint work with Thang Le)</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Shiyu Shen</div><div class="event_title">Title T.B.A.</div><div class="event_time">14:15 &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://stat.ethz.ch/events/zukost">ZüKoSt Zürcher Kolloquium über Statistik</a></div><br /><div class="event_speaker"> Arnoldo Frigessi (University of Oslo)</div><div class="event_title">Probabilistic preference learning from incomplete rank data <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Ranking data are ubiquitous: we rank items as citizens, as consumers, as scientists, and we are collectively characterised, individually classified and recommended, based on estimates of our preferences. Preference data occur when we express comparative opinions about a set of items, by rating, ranking, pair comparing, liking, choosing or clicking, usually in an incomplete and possibly inconsistent way. The purpose of preference learning is to i) infer on the shared consensus preference of a group of users, or ii) estimate for each user their individual ranking of the items, when the user indicates only incomplete preferences; the latter is an important part of recommender systems. I present a Bayesian preference-learning framework based on the Mallows rank model with any right-invariant distance, to infer on the consensus ranking of a group of users, and to estimate the complete ranking of the items for each user. MCMC based inference is possible, by importance-sampling approximation of the normalising function, but mixing can be slow. We propose a Variational Bayes approach to performing posterior inference, based on a pseudo-marginal approximating distribution on the set of permutations of the items. The approach scales well and has useful theoretical properties. Partial rankings and non-transitive pair-comparisons are solved by Bayesian augmentation. The Bayes-Mallows approach produces well-calibrated uncertainty quantification of estimated preferences, which are useful for recommendation, leading to excellent accuracy and increased diversity, compared for example to matrix factorisation. Simulations and real-world applications help illustrate the method. This talk is based on joint work with Elja Arjas, Marta Crispino, Qinghua Liu, Ida Scheel, Øystein Sørensen, and Valeria Vitelli. </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 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/kolloquium">Perlen-Kolloquium</a></div><br /><div class="event_speaker"> Prof. Roman Shvydkoy (University of Illinois at Chicago)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/perlenkolloquium-roman-shvydkoy-university-of-illinois-at-chicago/">Global relaxation for kinetic alignment models and the problem of emergence arising in systems of collective behavior</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Emergence is a phenomenon of formation of collective outcomes in systems where communication between agents has local range. For a wide range of applications, such as swarming behavior of animals or exchange of opinions between individuals, such outcomes result in a globally aligned state or congregation of aligned clusters. The classical result of Cucker and Smale states that alignment is unconditional in groups that facilitate global interactions with non-integrable radial tails. Proving a similar statement for purely local interactions is a challenging mathematical problem. There have been several programs of research directed  towards understanding the emergent phenomena on micro, kinetic, and macro levels of description. In this talk we will mostly focus on the kinetic approach and demonstrate its connection with the classical problem of relaxation for non-perturbative data.</div><div class="event_time">16:15 &bull; Universität Basel, Spiegelgasse 5, Raum 05.002</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">Cristina Caraci (Universität Zürich)</div><div class="event_title">Third order corrections to the ground state energy of a Bose gas in the Gross-Pitaevskii regime. <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider a system of N bosons confined in a unit box with periodic boundary conditions. We assume that the particles interact through a repulsive two-boxy potential with scattering length of order 1/N, i.e. the Gross-Pitaevskii regime. We establish a precise bound for the ground state energy E(N) of the system. While the leading contribution, of order N, to the energy has been known since the pioneering works of Lieb-Seiringer-Yngvason in the early 2000s, and the second order (of order one) corrections were more recently first determined by Boccato-Brennecke-Cenatiempo-Schlein, our estimate also resolves the next term in the asymptotic expansion of E(N), which is of the order (log N)/N, confirming Wu\'s predictions in 1959. Based on a joint work with Alessandro Olgiati, Diane Saint Aubin and Benjamin Schlein.</div><div class="event_time">16:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 46</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/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://math.ethz.ch/people/farkase">Prof. Dr. Erich Walter Farkas (ETH Z&uuml;rich, Switzerland)</a></div><div class="event_title">Local-stochastic volatility and pricing autocallables <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We investigate the pricing of single-asset autocallable barrier reverse convertibles in the Heston local-stochastic volatility (LSV) model. Despite their complexity, autocallable structured notes are the most traded equity-linked exotic derivatives. The autocallable payoff embeds an early redemption feature generating strong path- and model-dependency. Consequently, the commonly-used local volatility (LV) model is overly simplified for pricing and risk management. Given its ability to match the implied volatility smile and reproduce its realistic dynamics, the LSV model is, in contrast, better suited for exotic derivatives such as autocallables. We use quasi-Monte Carlo methods to study the pricing given the Heston LSV model and compare it with the LV model. In particular, we establish the sensitivity of the valuation differences of autocallables between the two models with respect to payoff features, model parameters, underlying characteristics, and volatility regimes. We find that the improved spot-volatility dynamics captured by the Heston LSV model typically result in higher prices, demonstrating the dependence of autocallables on the forward-skew and vol-of-vol risk. Moreover, we show that the parameters of the stochastic component of LSV models enable controlling for the autocallables price while leaving the fit to European options unaffected.The presentation is based on a joint work with Urban Ulrych and Francesco Ferrari and has grown from the Master Thesis of the latter.</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, April 12      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/number-theory-seminar">Number Theory Seminar</a></div><br /><div class="event_speaker"> Ingmar Metzler (Technische Universität Darmstadt)</div><div class="event_title">Theta lifts, special cycles and Rankin–Selberg convolutions <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Theta lifts have long been known for constructing examples of automorphic forms in different settings.The Borcherds lift, for instance, gives rise to remarkable product expansions in the orthogonal contextand allows to derive relations for special divisors. It is closely related to the Kudla–Millson lift and bothhave played a significant role in studying special divisors of Shimura varieties of orthogonal type. Theselifts were related to each other by Bruinier and Funke who also proved surjectivity/injectivity in severalcases. We present an approach to generalise these results, involving cycle integrals and Hecke theory, anddiscuss two new results, one of which was proven in collaboration with Riccardo Zuffetti.</div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/anmath/seminars/">Seminar of Analysis </a></div><br /><div class="event_speaker"> Ayman Said (Cambridge University)</div><div class="event_title">Small scale creation of the Lagrangian flow in 2d perfect fluids <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 present a recent result showing that for all solutions of the 2d Euler equations with initial vorticity with finite Sobolev smoothness then an initial data dependent norm  of the associated Lagrangian flow blows up in infinite time at least like $t^{\\frac{1}{3}}$. This initial data dependent norm quantifies the exact $L^2$ decay of the Fourier transform of the solution. This adapted norm turns out to be the exact quantity that controls a low to high frequency cascade whichI I will then show to be the quantitative phenomenon behind a microlocal generalised Lyapunov function constructed by Shnirelman.</div><div class="event_time">14:15 &bull; EPF Lausanne, MA B1 11</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>';