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. 10</span>      <span style="float: right; text-align:right; width: 250px;">20.4 - 24.4.2026</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2026</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, April 20      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/mpseminar/seminar.html">Séminaire de Mathématique Physique </a></div><br /><div class="event_speaker"> Aoteng  Xia</div><div class="event_title">Near-critical behavior of random field Ising model <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider the random field Ising model (RFIM) on an N-box in the integer lattice Z^2 with external field $\\eps h_v$ where $h_v$ are i.i.d. normal variables and study three objectives to detect criticality.For the boundary influence, i.e., the difference of the spin average at the origin under plus/minus boundary condition, we show that it decays as $N^{-\\frac{1}{8}}\\exp(-\\eps^{7/8}N)$ for $\\eps \\gg N^{-7/8}$.For the plus-minus interface with Dobrushin boundary condition, we show that it has a unique scaling limit which is absolutely continuous with respect to the law of SLE_3.For the nested loops of plus-minus interfaces, we show that any subsequential scaling limit is singular with respect to the law of CLE_3. Moreover, the singularity holds when only focusing on the outermost loops.Based on joint works with Jian Ding, Fenglin Huang and Leonie Papon.</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">Prof. Dr. Paul  Houston (University of Nottingham)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Fast Solution Techniques for the Numerical Approximation of the Linear Boltzmann Transport Problem: Application to Radiotherapy Treatment Planning</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk we develop efficient computational methods for the numerical approximation of the linear Boltzmann transport problem which models the fluence/flow of particles through a scattering and absorbing medium; this model is widely used in areas as diverse as medical imaging, radiotherapy treatment planning, and the design of nuclear reactors, for example. Here, we consider the design of so-called high–order/hp-–version discontinuous Galerkin finite element methods for the discretization of the governing integro-differential equation on general (spatial) computational meshes consisting of polytopic elements. Our particular interest is the application to medical treatment planning in clinical radiotherapy. Here we study both the stability and a priori error analysis of the proposed scheme. The implementation is based on exploiting a nodal approximation in energy and angle, together with fast numerical integration techniques on the spatial polytopic mesh; this approach leads to a highly parallelizable algorithm whereby a large number of linear transport solves must be computed. Additionally, we consider the design of iterative solution techniques for the resulting linear system of equations; in particular, we consider both a Richardson type iteration, as well as a Richardson preconditioned GMRES solver for both monoenergetic and polyenergetic problems. For the Richardson scheme, we prove convergence, independent of the discretisation parameters h and p, while GMRES is shown (computationally) to depend only mildly on h and p. Numerical experiments are presented to highlight the accuracy and performance of the proposed solver, as well as to benchmark with more standard kinetic Monte Carlo simulations.</div><div class="event_time">17:15 &bull; Universität Bern, Sidlerstrasse 5, 3012 Bern, Room B6</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, April 21      </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">  Neelam  (University of Utah)</div><div class="event_title">New perspectives on Grigorchuk-Machì Group <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Grigorchuk and Machì introduced a group &#915; of intermediate growth that is a subgroup of Aut(R). They do this by showing that the group is left-orderable. In 2008, Andres Navas gave an explicit description of a group G of homeomorphisms of [0,1]. In his paper, he mentions that G is isomorphic to the geometric realization of &#915;. In this talk, we prove this claim by showing that &#915; is isomorphic to G. In addition, we see that these groups are isomorphic to the braided Grigorchuk group defined by Skipper and Zaremsky in 2023 which has recently appeared in the study of big mapping class groups. More broadly, this construction of braiding Grigorchuk group fits into a program relating self-similar groups to their braided analogs. As an example of this, I will discuss a general theorem where the amenability property gets preserved under braiding.</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"> Martin J.  Gander</div><div class="event_title">Landmarks in the History of Iterative Methods III <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Iterative methods for linear systems were invented for the same reasons as they are used today, namely to reduce computational cost. Gauss states in a letter to his friend Gerling in 1823: "you will in the future hardly eliminate directly, at least not when youhave more than two unknowns".After a historical introduction to such classical stationary iterative methods, I will explain how the idea of extrapolation leads to Krylov methods, which are in fact not solvers but convergence accelerators.I will then introduce modern iterative methods for solving partial differential equations, which come in two main classes: domain decomposition methods and multigrid methods. These methods develop their full potential when used together with Krylov methods, namely as preconditioners.Joint work with Philippe Henry and Gerhard Wanner</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_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.unil.ch/dsa/en/home/menuinst/seminaires--evenements/research-seminars.html">Talks in Actuarial Mathematics </a></div><br /><div class="event_speaker"> Christoph  Thäle (University of Bochum, Germany)</div><div class="event_title">Seeing Through Hyperbolic Space <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This talk explores recent advances in hyperbolic stochastic geometry, focusing on random tessellations and Boolean models in the $d$-dimensional hyperbolic space $\\mathbb{H}^d$. First, we investigate the zero cell in a hyperbolic Poisson hyperplane tessellation, analyzing its first and second-order volume moments alongside its critical phase transition. Building on these geometric properties, we then explore visibility problems, comparing our findings to the visibility horizons observed in hyperbolic Boolean models and general $\\lambda$-geodesic hyperplane processes.</div><div class="event_time">14:00 &bull; EPF Lausanne, Extranef  125</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Jérémy  Toulisse</div><div class="event_title">Higgs bundles and isomonodomy <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />After recalling what is a Higgs bundle on a Riemann surface X, I will explain first that the moduli space of Higgs bundles on X is a quasi-projective variety with a fascinating geometry. By the nonabelian Hodge correspondence, it parametrizes the character variety, that is the space of local systems on the smooth surface underlying X. The dependence on X of this correspondence is difficult to track, and so one cannot use it to study the action of the mapping class group on the character variety. In this talk, I will present a gauge theoretical construction of the joint moduli space of Higgs bundles, where the underlying Riemann surface is allowed to vary in the Tiechmüller space. The nonabelian Hodge correspondence the defines a foliation on this space whose holonomy recover the mapping class group action on the character variety. This is a joint work with Brian Collier and Richard Wentworth.</div><div class="event_time">14:15 &bull; EPF Lausanne, CM 1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_dis"><a class="external" href="https://unidistance.ch">UniDistance Suisse</a></div><div class="event_type"><a class="external" href="https://unidistance.ch/en/mathematiques-et-informatique/recherche/number-theory/number-theory-seminar">Number Theory Seminar</a></div><br /><div class="event_speaker"> Luca  Mastella  (UniDistance Suisse)</div><div class="event_title">CM points on Shimura curves and anticyclotomic Iwasawa theory of GL_2 abelian varieties <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will report on a work in progress with Ahmed Matar and Francesco Zerman, which aims to generalize some results of Matar and Jan Neková&#345; on anticyclotomic Iwasawa Theory of elliptic curves defined over Q to GL_2 “modular” abelian varieties over a totally real number field. In the talk I will explain how to achieve this aim applying a suitable version of Kolyvagin’s method to the Euler system of CM points on quaternionic Shimura curves.</div><div class="event_time">15:00 &bull; <a class="external" href="https://tinyurl.com/UniDistanceNTSeminar">UniDistance Suisse, Zoom</a></div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker"> Nicolas  Marque (Institut Elie Cartan de Lorraine/ Nancy)</div><div class="event_title">Conserved quantities in 2nd and 4th order Geometric Gravitational Theories <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />General Relativity modelizes gravity as an elastic behavior of spacetime described in a Lagrangian fashion by the Einstein-Hilbert energy. Applying principles of Noether\'s Theorem one can then exploit symmetries of a given model to obtain conserved quantities measuring  how far an Einsteinian spacetime (or an interesting spaceslice of it) is from the model. Among those, the mass of an Asymptotically Euclidean manifold (seen as the conserved quantity induced by the time translational symmetry of the Euclidean slice in Minkowski spacetime) stands out for its application to Riemannian geometry with the Positive Mass Theorem. After explaining the principles of construction and trying to give a feel of the nature of such conserved quantities, we will apply them to a fourth order gravitational theory and explore the Riemannian consequences.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://sites.google.com/view/agms-fribourg-seminars/home">Seminar Analysis and geometry on metric spaces</a></div><br /><div class="event_speaker"> Ilmari Kangasniemi (University of Jyväskylä)</div><div class="event_title">On the moduli of Lipschitz homology classes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk, we discuss a joint work with Prywes, where we study an alternative notion of p-modulus for families of Lipschitz k-chains that uses differential forms instead of density functions. The case k=1 corresponds to a vector modulus previously considered by Aikawa and Ohtsuka. The motivation for this definition lies in duality questions. For two opposite faces of a Lipschitz n-cube in &#8477;&#8319;, the moduli of connecting paths and separating (n-1)-surfaces satisfy an exact duality result. However, for other codimensional pairs, only one half of an analogous duality result has been proven, by work of Lohvansuu. Our alternate modulus does satisfy a form of exact duality, and is bounded from below by the classical modulus; thus, we obtain a type of generalization of Lohvansuu\'s upper bound to a wider class of Lipschitz Riemannian manifolds with boundary, and show that studying duality questions for the classical modulus is equivalent with studying whether the classical modulus coincides with this differential form modulus.</div><div class="event_time">15:15 &bull; Université de Fribourg, PER23 room 0.05</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_ge"><a class="external" href="https://unige.ch">Université de Genève</a></div><div class="event_type"><a class="external" href="https://www.unige.ch/math/seminaires/lie-sem/">Lie groups and moduli spaces </a></div><br /><div class="event_speaker"> Nikita Markarian (Strasbourg)</div><div class="event_title">Geometric approach to double shuffle relations <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Inspired by the work of Deligne–Terasoma, I will present a geometric approach to the double shuffle relations. In particular, I will explain how the pentagon equation implies the regularized double shuffle relations for formal multiple zeta values. I will then introduce a relation, which I call the homological pentagon equation, and show that it is implied by the pentagon equation and is equivalent to the regularized double shuffle relations. If time permits, I will discuss how this approach leads to a connection between the harmonic coproduct and the Turaev cobracket.</div><div class="event_time">15:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat075.1">Zurich Graduate Colloquium</a></div><br /><div class="event_speaker">Silvan Horvath (ETH)</div><div class="event_title">What is... forcing? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />&lt;p>Forcing is arguably the most versatile and widely used technique for proving consistency and independence results in set theory and in mathematics more generally. The aim of this talk is to introduce this method and to use it to prove that the continuum hypothesis is independent of ZFC. No prior knowledge is required.&lt;/p></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 22      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Yuxiang Jiao (Universtität Zürich)</div><div class="event_title">Dimension theory of fractals on the circle <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />&lt;p>&lt;span style="caret-color: #ffffff; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">By an elementary topological argument, any group of circle homeomorphisms that has no finite orbits and does not act minimally on the circle preserves a unique Cantor-like minimal set. The classical Patterson-Sullivan theory of Fuchsian groups fully describes the dimensional properties of these fractal sets whenever the group acts by \\(\\mathrm{PSL}_2(\\mathbb R)\\) elements. For more general smooth actions, a previous result by Deroin-Kleptsyn-Navas asserts that such a minimal set is always a Lebesgue null set in the real analytic category.&lt;/span>&lt;/p> &lt;div style="caret-color: #ffffff; color: #ffffff; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-line: none; text-decoration-thickness: auto; text-decoration-style: solid;">&lt;span style="color: #000000;">In this same setting, we establish a dimension theory for these fractal sets, which extends the classical Patterson-Sullivan theory to a broad smooth setting. In particular, we show that the Hausdorff and box dimensions of such minimal sets always coincide and are strictly less than one, which also improves upon the result of Deroin-Kleptsyn-Navas. This talk is based on joint work with Weikun He, Disheng Xu, and Wenyuan Yang.&lt;/span>&lt;/div></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_la"><a class="external" href="https://www.epfl.ch">EPFL Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/epfl-topology-seminar-spring-2026/">Séminaire de Topologie </a></div><br /><div class="event_speaker"> Annika Thiele (Humboldt-Universität zu Berlin)</div><div class="event_title"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/epfl-topology-seminar-spring-2026/">Symplectic fillings and spinal open books</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The classification of the symplectic fillings of a given contact 3-manifold poses an interesting problem. It is motivated by results that demonstrate that the symplectic fillings of a contact 3-manifold hold information on the contact structure. Most notably, the contact structure of any contact 3-manifold that admits a strong symplectic filling is tight. Although the symplectic fillings of certain contact manifolds have been classified, the general classification remains an open problem. Working towards this, one can consider the geography problem for symplectic fillings. In the paper Spine removal surgery and the geography of symplectic fillings, Sam Lisi and Chris Wendl prove the existence of a universal bound for the geography (Euler characteristic and signature) of possible minimal strong symplectic fillings of a closed contact 3-manifold with a supporting planar spinal open book decomposition. Following a brief introduction to symplectic and contact topology, the aim of my talk is to explain Lisi and Wendl\'s result. For this purpose, I will provide an overview of symplectic fillings and the related geography problem, and introduce spinal open book decompositions.  </div><div class="event_time">14:15 &bull; <a class="external" href="https://plan.epfl.ch/?room==MA%20B1%20504">EPFL Lausanne, MA B1 504</a></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/stoan/probability-stochastic-analysis-seminar/">Probability (and Stochastic Analysis) Seminar </a></div><br /><div class="event_speaker"> Tom  Hutchcroft  (CalTech)</div><div class="event_title">Critical long-range percolation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It is conjectured that many models of statistical mechanics have a rich, fractal-like behaviour at and near their points of phase transition, with power-law scaling governed by critical exponents that are expected to depend on the dimension but not on the small-scale details of the model such as the choice of lattice. This is now reasonably well understood in two dimensions and in high dimensions, but remains poorly understood in intermediate dimensions (e.g. d=3). I will overview the conjectures around this area and describe recent progress on related problems for models with long-range interactions.</div><div class="event_time">15:15 &bull; EPF Lausanne, CM 1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/geometry-seminar">Geometry Seminar</a></div><br /><div class="event_speaker"> Ara Basmajian (City University of New York)</div><div class="event_title">From Collars on Riemann surfaces to Tubes in Complex Ball quotients <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The celebrated Keen collar lemma guarantees that a simple closed geodesic on a hyperbolic Riemann surface has a collar (tubular neighborhood) whose width only depends on its length. Viewing a Riemann surface as the quotient of the unit ball in the complex plane, a natural generalization is to ball quotients in higher dimensions where the Poincaré metric is replaced by the Bergman metric (also known as the complex hyperbolic metric). Such ball quotients are called complex hyperbolic manifolds. The focus of this talk will be on embedded complex geodesics in complex hyperbolic 2-manifolds; a complex geodesic has complex codimension one in the quotient complex 2-manifold. We prove a tubular neighborhood theorem for such a complex geodesic where the width of the tube depends only on the Euler characteristic of the embedded complex geodesic. We also derive an explicit estimate for this width. After giving a short history of the collar lemma generalizations and discussing the basics of complex hyperbolic geometry, we will discuss the ideas leading to the proof of this tubular neighborhood theorem. This is joint work with Youngju Kim.</div><div class="event_time">15:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_be"><a class="external" href="https://www.unibe.ch">Universität Bern</a></div><div class="event_type"><a class="external" href="https://www.imsv.unibe.ch/research/talks/colloquia/index_eng.html">Colloquia on Probability and Statistics </a></div><br /><div class="event_speaker">Prof. Dr. Christoph Thäle (Ruhr-Universität Bochum)</div><div class="event_title"><a class="external" href="https://www.imsv.unibe.ch/research/talks/schedule/index_eng.html">Seeing Through Hyperbolic Space</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This talk explores recent advances in hyperbolic stochastic geometry, focusing on random tessellations and Boolean models in the $d$-dimensional hyperbolic space $\\mathbb{H}^d$. First, we investigate the zero cell in a hyperbolic Poisson hyperplane tessellation, analyzing its first and second-order volume moments alongside its critical phase transition. Building on these geometric properties, we then explore visibility problems, comparing our findings to the visibility horizons observed in hyperbolic Boolean models and general $\\lambda$-geodesic hyperplane processes.</div><div class="event_time">16:15 &bull; Universität Bern, Hörsaal B78, ExWi, Sidlerstrasse 5, 3012 Bern</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. Dongbin Xiu (The Ohio State University, USA)</div><div class="event_title">Modeling Observable Dynamics: Flow Map Learning and Delay Representation <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We present a mathematical and numerical framework for modeling the dynamics of observables in complex systems, termed Flow Map Learning (FML). Rather thanapproximating governing equations, FML constructs discrete-time evolution operators directly from data, enabling accurate prediction of the observables even when theunderlying full system is unknown. We establish that, for a broad class of systems, observable dynamics admit finite-dimensional delay representations, leading to closed evolution equations with minimal memory. This perspective provides a foundation forincorporating temporal dependence in data-driven models and fast predictions of observable dynamics. We then present various numerical examples to demonstrate theefficacy of FML for long-time prediction of observable dynamics.</div><div class="event_time">16:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.2</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Dr. Yuhao Xue (IHES)</div><div class="event_title">The spectral gap of Weil-Petersson random cusped hyperbolic surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Weil-Petersson metric on the moduli space of hyperbolic surfaces with $g$ genus and $n$ cusps is of finite volume, and hence induce a probability measure and a model of random cusped surfaces. The study of nearly optimal spectral gap for random closed hyperbolic surfaces is a great breakthrough in recent years. In this talk, we consider the Weil-Petersson random cusped hyperbolic surfaces, and show a uniform lower bound of the spectral gap when $n=o(\\sqrt{g})$. We will carefully introduce the knowledge of Weil-Petersson random hyperbolic surfaces and the spectrum in the beginning. The talk is based on the joint work with Yuxin He and Yunhui Wu.</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, April 23      </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">EPFL Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/epfl-topology-seminar-spring-2026/">Séminaire de Topologie </a></div><br /><div class="event_speaker"> Elena Botti (Vrije Universiteit Brussel)</div><div class="event_title"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/epfl-topology-seminar-spring-2026/">Topological Data Analysis for Gait Pattern Classification</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The classification of gait patterns is an important challenge in movement analysis, as it supports clinical assessment and decision-making by enabling diagnosis and severity stratification. In this talk, I will discuss the potential of Topological Data Analysis (TDA) for gait pattern classification. Unlike conventional approaches that rely on explicit detection of Gait Events (GEs) to compute Spatiotemporal Gait Parameters (SGPs), TDA characterises the global structure of gait signals directly, capturing relationships and patterns in the data without requiring GEs. This is particularly relevant in real-world settings, where GE detection can be diQicult due to heterogeneity in walking conditions and gait patterns, potentially biasing clinically relevant metrics and, consequently, decision-making.Within our department, preliminary results have shown that TDA-based features can achieve classification performance comparable to that of SGPs in fall-risk assessment. These findings suggest that topology oQers a competitive alternative for representing gait data, with the potential to better handle variability across subjects and pathological conditions.Building on these results, we plan to further extend the TDA framework in two directions. First, we aim to investigate time-aware topological methods to better capture the temporal structure of gait signals. Second, we will explore Topological Deep Learning (TDL) approaches to reduce reliance on handcrafted design choices and potentially improve classification performance. By combining the robustness of topology with data- driven representation learning, this work seeks to provide robust tools for the classification of typical and pathological gait patterns.</div><div class="event_time">10:00 &bull; <a class="external" href="https://plan.epfl.ch/?room==CM%201%20517">EPFL Lausanne</a></div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Sylvain Crovisier (Université Paris-Saclay)</div><div class="event_title">Ergodic theory of surface diffeomorphisms</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_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"> Mohsen Shahidkalhori (Universität Basel)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/studium/mathematik/doktorat/bernoullis-tafelrunde/detail/bernoullis-tafelrunde-mohsen-shahidkalhori-universitaet-basel/">Frequency Functions: From Unique Continuation to Singular Sets</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Abstract Frequency functions provide a quantitative way to measure how fast a function vanishes. For harmonic maps, the key fact is that the frequency function is monotone, and this already has remarkable consequences: it leads to quantitative unique continuation and prevents solutions from vanishing too rapidly. In particular, touching sets of harmonic functions are necessarily small, with codimension at least two. In this talk, we use this viewpoint as a guiding principle for more geometric problems. In minimal surface theory, singularities arise from sheets touching each other, suggesting that similar ideas should apply. We first examine the linear model given by multi-valued Dirichlet minimizers, where frequency methods again yield the same dimension bounds for the singular set, and then briefly discuss why extending this approach to minimal surfaces is substantially more subtle.</div><div class="event_time">12:15 &bull; Universität Basel, Seminarraum 05.001, Spiegelgasse 5</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"> Álvaro  Del Valle (Universidad de Sevilla)</div><div class="event_title">Turaev genus and arc index: a new conjecture for links <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Turaev genus $g_T$ is a numerical invariant of knots and links that measures how far a link is from being alternating (that is, from admitting an alternating diagram). Determining whether a link is alternating is, in general, not straightforward. In this work we compare the Turaev genus with another numerical invariant, the arc index $\\alpha$. In particular, we conjecture that $c(L) + 2 - \\alpha(L) \\geq 2 g_T(L)$ for any prime, non-split link L, where $c(L)$ is the number of crossings of L. We present various techniques to verify the conjecture for relevant families of links: adequate links, closures of positive 3-braids, torus links, and Kanenobu knots. This is joint work with Adam M. Lowrance.</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Seminar Room, 8th floor,</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"> Francesca Carocci</div><div class="event_title">The multiple cover formula conjecture for Gromov-Witten invariants of abelian surfaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Abelian surfaces are complex tori whose enumerative invariants satisfy remarkable regularity properties. The computation of their (reduced) Gromov-Witten invariants for the so called primitive classes is fairly well understood and many complete computations are available. A few years ago, G. Oberdieck conjectured a multiple cover formula expressing in a very simple way the invariants for the non-primitive classes in terms of the primitive one. The proof of the conjecture would solve completely the GW theory of abelian surfaces.In this talk, we\'ll sketch a proof of multiple cover formula conjecture for many insertions. The argument relies on a reduced degeneration formula and on the computation of correlated Gromov-Witten invariants for trivial bundles on elliptic curves.  This is joint work with T. Blomme</div><div class="event_time">14:15 &bull; EPF Lausanne, CM 1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_be"><a class="external" href="https://www.unibe.ch">Universität Bern</a></div><div class="event_type"><a class="external" href="https://www.imsv.unibe.ch/research/talks/colloquia/index_eng.html">Colloquia on Probability and Statistics </a></div><br /><div class="event_speaker">Prof. Dr. Jelle J. Goemann</div><div class="event_title"><a class="external" href="https://www.imsv.unibe.ch/research/talks/schedule/index_eng.html">Bringing Closure to False Discovery Rate Control: A General Principle for Multiple Testing</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We present a novel necessary and sufficient principle for multiple testing methods controlling an expected loss. This principle asserts that every such multiple testing method is a special case of a general closed testing procedure based on e-values. It generalizes the Closure Principle, known to underlie all methods controlling familywise error and tail probabilities of false discovery proportions, to a large class of error rates -- in particular to the false discovery rate (FDR). By writing existing methods as special cases of this procedure, we can achieve uniform improvements, as we demonstrate for the e-Benjamini-Hochberg and the Benjamini-Yekutieli procedures, and the self-consistent method of Su (2018). We also show that methods derived using our novel e-Closure Principle generally control their error rate not just for one rejected set, but simultaneously over many, allowing post hoc flexibility for the researcher.Moreover, we show that because all multiple testing methods for all error metrics are derived from the same procedure, researchers may even choose the error metric post hoc. Under certain conditions, this flexibility even extends to post hoc choice of the nominal error rate.</div><div class="event_time">16:15 &bull; Universität Bern, Hörsaal B7, ExWi, Sidlerstrasse 5, 3012 Bern</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/colloque">Colloque de Mathématiques </a></div><br /><div class="event_speaker"> Thomas Vidick (EPFL)</div><div class="event_title">Inapproximability through undecidability  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Infinite combinatorial, algebraic or other structures, such as a graph, a group, or aprobability space, can sometimes be approximated (in a suitable sense) by finite structures, andsometimes not. In the former case, finite approximability can provide a convenient proxy for studyingthe infinite structure; in the latter, inapproximability underscores a genuinely distinct behavior fromthe finite case. While the existence of finite approximations can follow from suitable approximationtechniques, their in-existence often requires deeper conceptual observations.Recently we were able to resolve some long-standing inapproximability questions, in algebra and inergodic theory, by showing that an associated computational problem is undecidable. Associating ameasure of complexity to the infinite structure allows us to make use of methods from complexitytheory and demonstrate the in-existence of finite approximations in an unexpected way.In the talk we will discuss this "method" and show how we used it to answer the Connes EmbeddingProblem, about the existence of inapproximable classes of (type II_1) von Neumann algebras, and theAldous-Lyons conjecture, about the existence of inapproximable (unimodular) infinite graphs.Based on joint works with Ji, Natarajan, Yuen and Wright, and Bowen, Chapman and Lubotzky.</div><div class="event_time">16:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-15</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://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. Eyal Neuman (Imperial College London)</div><div class="event_title"> Stochastic Games on Large Sparse Graphs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We introduce a framework for stochastic games on large sparse graphs, covering continuous-time and discrete-time dynamic games as well as static games. Players are indexed by the vertices of simple, locally finite graphs, allowing both finite and countably infinite populations, with asymptotics described through local weak convergence of marked graphs. The framework allows path-dependent utility functionals that may be heterogeneous across players. Under a contraction condition, we prove existence and uniqueness of Nash equilibria and establish exponential decay of correlations with graph distance. We further show that global equilibria can be approximated by truncated local games, and can even be reconstructed exactly on subgraphs given information on their boundary. Finally, we prove convergence of Nash equilibria along locally weakly convergent graph sequences, including sequences sampled from hyperfinite unimodular random graphs. This is a joint work with Sturmius Tuschmann. </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 24      </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"> Tom Hutchcroft (California Institute of Technology (Caltech))</div><div class="event_title">Dimension dependence of critical phenomena in percolation</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://sites.google.com/view/pm-seminar/home">Physical Mathematics Seminar</a></div><br /><div class="event_speaker"> Alessandro Testa</div><div class="event_title">Probing ABJM theories through Tracy-Widom formalism <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br /> In this talk, we will present a unified Fermi-gas framework for computing BPS observables in ABJM theory on S^3. Supersymmetric localization reduces the problem to an interacting matrix model that can be interpreted as a one-dimensional ideal Fermi gas, whose dynamics is encoded in a set of functional relations and TBA-like equations. We will show that these equations enable a non-perturbative approach that systematically captures the instanton sectors of the free energy and winding Wilson loops. As applications, we will provide an analytic proof of several expressions previously obtained by complementary techniques and derive closed-form expressions, valid at arbitrary winding number, for the leading membrane- and worldsheet-instanton corrections to the 1/6- and 1/2-BPS Wilson loops.</div><div class="event_time">14:00 &bull; Université de Genève, Conseil Général 7-9, Room 8-02</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/number-theory-seminar">Number Theory Seminar</a></div><br /><div class="event_speaker">Dr. Rustam Steingart (Universität Heidelberg)</div><div class="event_title">Iwasawa cohomology for general p-adic Lie extensions via vector bundles on the Fargues--Fontaine curve <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will report on joint work in progress with Joaquín Rodrigues Jacinto and Gautier Ponsinet concerning Iwasawa cohomology of vector bundles on the Fargues--Fontaine curve along a (deeply ramified) p-adic Lie extension $K_\\infty/K$. By working with derived analytic vectors we obtain a reinterpretation of classical results for bundles of slope 0 for any p-adic Lie extension. For general slopes we obtain a reinterpretation in terms of the (dual of the) \\psi=1 Eigenspace of $(\\varphi,\\Gamma)$-modules in the case that $K_\\infty/K$  is the cyclotomic extension. For general $p$-adic Lie extensions the latter is badly behaved while the former can still be defined and is expected to be well-behaved. I will focus on the Lubin--Tate case in which we can prove this expectation. If time permits I will mention some partial results for SL_2 and difficulties in the general case.</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"> Javier  Penafiel - Tomas (ICMAT, Madrid)</div><div class="event_title">Topological properties of rough fluids and plasmas</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"> Jelle  Goeman (University of Leiden)</div><div class="event_title">Bringing Closure to False Discovery Rate Control: A General Principle for Multiple Testing <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We present a novel necessary and sufficient principle for multiple testing methods controlling an expected loss. This principle asserts that every such multiple testing method is a special case of a general closed testing procedure based on e-values. It generalizes the Closure Principle, known to underlie all methods controlling familywise error and tail probabilities of false discovery proportions, to a large class of error rates -- in particular to the false discovery rate (FDR). By writing existing methods as special cases of this procedure, we can achieve uniform improvements, as we demonstrate for the e-Benjamini-Hochberg and the Benjamini-Yekutieli procedures, and the self-consistent method of Su (2018). We also show that methods derived using our novel e-Closure Principle generally control their error rate not just for one rejected set, but simultaneously over many, allowing post hoc flexibility for the researcher.Moreover, we show that because all multiple testing methods for all error metrics are derived from the same procedure, researchers may even choose the error metric post hoc. Under certain conditions, this flexibility even extends to post hoc choice of the nominal error rate.</div><div class="event_time">15:15 &bull; EPF Lausanne, CM 1 517</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Andrea Brini (University of Sheffield)</div><div class="event_title">On the conifold gap for local P2 <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The `conifold gap\' conjecture asserts that the polar part of the Gromov-Witten potential of a Calabi-Yau threefold near its conifold locus has a universal expression described by the logarithm of the Barnes G-function. In this talk I will describe a proof of the Conifold Gap Conjecture for the local projective plane, whereby the higher genus conifold Gromov-Witten generating series of local P2 are related to the thermodynamics of a certain statistical mechanical ensemble of repulsive particles on the positive half-line. As a corollary, this establishes the all-genus mirror principle for local P2 through the direct integration of the BCOV holomorphic anomaly equations.</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>';