var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-2"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=0"><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. 14</span>      <span style="float: right; text-align:right; width: 250px;">15.12 - 19.12.2025</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Autumn Semester 2025</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, December 15      </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://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker"> Kshiteej  Sheth</div><div class="event_title">Sublinear Time Low-Rank Approximation of Hankel Matrices <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Hankel matrices are an important class of highly-structured matrices, arising across computational mathematics, engineering, and theoretical computer science. It is well-known that positive semidefinite (PSD) Hankel matrices are always approximately low-rank. In particular, a celebrated result of Beckermann and Townsend shows that, for any PSD Hankel matrix H &#8712; R n×n and any &#1013; > 0, letting Hk be the best rank-k approximation of H (obtained via truncated singular value decomposition), &#8741;H &#8722; Hk&#8741;F &#8804; &#1013;&#8741;H&#8741;F for k = O(log n log(1/&#1013;)). I.e., the optimal low-rank approximation error decays exponentially in the rank-k. As such, PSD Hankel matrices are natural targets for low-rank approximation algorithms. We give the first such algorithm that runs in sublinear time. In particular, we show how to compute, in polylog(n, 1/&#1013;) time, a factored representation of a rank-O(log n log(1/&#1013;)) Hankel matrix Hb matching the error guarantee of Beckermann and Townsend up to constant factors. We further show that our algorithm is robust – given input H + E where E &#8712; R n×n is an arbitrary non-Hankel noise matrix, we obtain error &#8741;H &#8722; Hb&#8741;F &#8804; O(&#8741;E&#8741;F ) + &#1013;&#8741;H&#8741;F . Towards this algorithmic result, our first contribution is a structure-preserving existence result - we show that there exists a rank-k Hankel approximation to H matching the error bound of Beckermann and Townsend. Our result can be interpreted as a finite-dimensional analog of the widely applicable AAK theorem, which shows that the optimal low-rank approximation of an infinite Hankel operator is itself Hankel. Armed with our existence result, and leveraging the well-known Vandermonde structure of Hankel matrices, we achieve our sublinear time algorithm using a sampling-based approach that relies on universal ridge leverage score bounds for Vandermonde matrices.</div><div class="event_time">11:00 &bull; EPF Lausanne, INJ114</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"> Eugenia Malinnikova (Stanford University)</div><div class="event_title">Carleman estimates, unique continuation, and Landis conjecture</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_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-mathematical-physics">Talks in Mathematical Physics</a></div><br /><div class="event_speaker"> Ödül Tetik (University of Vienna)</div><div class="event_title">A generalised Poisson additivity <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Poisson additivity theorem of Rozenblyum–Safronov gives an equivalence between the category of n-disk algebras valued in 1-shifted Poisson algebras and the category of (1-n)-shifted Poisson algebras. Seeing this as a topological statement on a coordinate patch, I will discuss a generalisation of this theorem to a non-topological statement on arbitrary (but non-stratified) spacetimes, building on an approach due to Tamarkin. The key novel notion is that of a factorisation Lie algebra. This is joint work in preparation with Giovanni Canepa and Nils Carqueville.</div><div class="event_time">13:30 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/symplectic-geometry-seminar">Symplectic Geometry Seminar</a></div><br /><div class="event_speaker"> Renato Vianna  (University of São Paulo)</div><div class="event_title">Open-string Quantum Lefschetz formula <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Let Y be a symplectic divisor of X, \\omega. In the Kahler setting, Givental\'s (closed-string) Quantum Lefschetz formula relates certain Gromov-Witten invariants (encoded by the G function) of X and Y. Given an Lagrangian L in (Y, \\omega|Y), we can lift it to a Lagrangian L\' in neighbourhood NY \\subset X. We will introduce the notion of the potential of a Lagrangian, which encodes information of Maslov index 2 J-holomorphic disks with boundary on it.From the work of Biran-Khanevski, we can extract a formula for when (X,L\',Y,L) forms a monotone tuple (we will define this notion), and the minimal Chern number of Y is 2. We generalise the formula in this setting when we allow the minimal Chern number to be 1. We can use this to show the existence of infinitely many Lagrangian tori in CP^n, Quadrics, Cubics, and other symplectic manifolds, among other results.Following the work of Tonkonog on gravitational descendants, we recover an explicit Quantum Lefschetz formula appearing in the work of Coates-Corti-Galkin-Kasprczyk. Interestingly, their formula applies in a different context--specifically when X is toric -- which neither contains nor is contained in the monotone tuple setting. Motivated by this, we introduce an alternative set of hypotheses, typically satisfied when X degenerates to a toric manifold, under which a broader open-string Quantum Lefschetz formula applies. The differences between these sets of hypotheses will be discussed. This is joint work with Luis Diogo, Dmitry Tonkonog and Weiwei Wu.</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"> Christian  Brennecke  (University of Bonn)</div><div class="event_title">Title T.B.A.</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. Peter Schuster (University of Verona)</div><div class="event_title"><a class="external" href="https://www.math.unibe.ch/research/talks/colloquium/index_eng.html">Terms for Termination</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />When computing with polynomials over a field, (monic) monomials are the prime tool for termination and finite generation: among monomials, ideal membership is divisibility by a generator, and divisibility is the natural order on the exponents; in particular, Dickson’s lemma applies. Over a field, every non-zero term, i.e. monomial with coefficient, can be made monic, by inverting the coefficient. Over a general commutative ring, terms proper have proved the key link to the polynomial ring, and in fact help to a constructive proof of the iterative Hilbert basis theorem with Noether\'s chain condition in Richman’s guise.Joint work with Ihsen Yengui.</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, December 16      </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/algebraische-geometrie/">Seminar Algebra and Geometry</a></div><br /><div class="event_speaker"> Joseph Malbon (Edinburgh)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-algebra-and-geometry-joseph-malbon-edinburgh/">Automorphisms and K-stability of a family of smooth Fano threefolds</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We describe the automorphism groups of smooth Fano threefolds of Picard rank 2 and anticanonical degree 28. We then use this to determine which of these threefolds are K-polystable, and relate the corresponding K-moduli space to a certain GIT-quotient.</div><div class="event_time">10:30 &bull; Universität Basel, Seminarraum 00.003, Spiegelgasse 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/fim/activities/nachdiplom-lectures">Nachdiplomvorlesung</a></div><br /><div class="event_speaker"> Eva Miranda (Universitat Politècnica de Catalunya)</div><div class="event_title">Singular Symplectic Manifolds</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/annonces/seminaire-danalyse-numerique">Séminaire d\'Analyse Numérique </a></div><br /><div class="event_speaker"> Jing  Lyu (University of Geneva)</div><div class="event_title">Optimized Schwarz Waveform Relaxation method for a parabolic interface problem with quadratic jump <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We focus on the heterogeneous optimized Schwarz waveform relaxation (OSWR) algorithm for solving a parabolic interface problem coupled with nonlinear (quadratic) interface jump conditions. This mathematical model problems was introduced to describe the concentration of an ion between the aqueous solution and the adjoining polymeric membrane. To handle the nonlinearity, we establish flexible linear transmission conditions used in the heterogeneous OSWR, including the standard Robin, the scaled Robin, and the two-sided Robin conditions. The free parameters involved are then optimized in a Fourier analysis framework, and the corresponding convergence rate estimates are obtained in an asymptotic sense. Our study reveals that the stronger the heterogeneity contrast is, the faster the algorithm converges, where the new heterogeneity parameter consists not only of the diffusion coefficient and the width of the media, but also the interface parameters. Particularly, the two-sided Robin condition is time mesh independent. Finally, we illustrate our theoretical results using several numerical experiments. Our OSWR algorithm can also be extended to many other multi-physics problems that are non-linearly coupled along the interface.</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://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"> Javier Fresan (Institut de mathematiques de Jussieu, Paris)</div><div class="event_title">Sidon sets, Larsen\'s alternative, exponential sums, andrandom graphs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A Sidon set is a subset S of an abelian group A with theproperty that elements of A cannot be sums of two elements of S in more thanone way. Larsen\'s alternative is a criterion to decide whether a compactsubgroup K of the group of unitary matrices is as large as possible in terms ofthe fourth moment of K. I will explain how to construct Sidon sets coming fromalgebraic geometry, and how Larsen\'s alternative allows us to prove explicitequidistribution statements for some exponential sums over finite fieldssupported at those Sidon sets. Building on this, we can construct families ofgraphs that, on the one hand, have eigenvalues that are asymptoticallydistributed according to the Sato-Tate measure, but on the other hand are verydifferent from random graphs, for example in that they do not contain K_{2, 3}as a subgraph. This is a joint work with Arthur Forey, Emmanuel Kowalski, andYuval Wigderson. (30 minutes general talk, followed by 45minutes of more specialized talk)</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_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"> Tian Lan (ETH Z&uuml;rich, Switzerland)</div><div class="event_title">The regularity of scale-invariant Lagrangians depending on the first and second fundamental forms. <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 discuss some scale-invariant curvature energies depending on the first and second fundamental forms, with an emphasis on the regularity theory. We focus on the Dirichlet energy of the mean curvature for four-dimensional hypersurfaces and present a regularity theorem for weak critical points. The proof uses Noether-type conservation laws to rewrite the Euler–Lagrange equation as a lower-order elliptic system, where tools from integrability by compensation and interpolation theory apply; I will also highlight the additional difficulties compared with the two-dimensional Willmore setting. This is based on a joint work with Yann Bernard, Dorian Martino, and Tristan Rivière.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, December 17      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://calendar.google.com/calendar/embed?mode=AGENDA&height=600&wkst=2&bgcolor=%23FFFFFF&src=t36it03v52cus2detrvinlgk18%40group.calendar.google.com&color=%235F6B02&ctz=Europe%2FZurich">Groups, Arithmetic and Algebraic Geometry Seminar </a></div><br /><div class="event_speaker"> Tanguy Vernet</div><div class="event_title">Quiver varieties with multiplicities <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Representations of quivers with multiplicities are representations of quiversover rings of truncated power series. Such representations were studied byGeiss, Leclerc and Schröer in a series of works, where connections withsymmetrisable Kac-Moody algebras were established. These results generaliseearlier constructions of Lusztig, Kashiwara and Saito from symmetric tosymmetrisable Kac-Moody algebras.I will report on joint work with Victoria Hoskins and Joshua Jackson, where weconstruct analogues of Nakajima quiver varieties for quivers withmultiplicities. Our construction relies on Geometric Invariant Theory resultsfor non-reductive groups due to Hamilton, Hoskins and Jackson. We definestability conditions for quiver representations with multiplicities,generalising the stability conditions introduced by King in the nineties. Timepermitting, I will discuss a conjectural construction of nilpotent quivervarieties with multiplicities and applications to geometric realisations ofcrystals for irreducible highest-weight representations of symmetrisableKac-Moody algebras.</div><div class="event_time">10:15 &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://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Dr. Nicholas Fleming (University of Toronto)</div><div class="event_title">Statistical properties of certain 2D mostly expanding fast-slow systems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />&lt;p>This is joint work with Jacopo De Simoi and Kasun Fernando. We consider a class of sufficiently smooth partially hyperbolic fast-slow systems on the 2-torus, obtained by a size &epsilon; perturbation of a trivial extension of a family of expanding circle maps. Such fast-slow systems obey an averaging principle: at time-scale 1/&epsilon; the slow part is approximated by the solution of an ODE. Assuming that this ODE has exactly one sink and both Lyapunov exponents of the system are positive, we prove the system admits a unique physical (SRB) measure. Moreover, we establish exponential decay of correlations, with explicit, nearly optimal bounds on the decay rate.<br>This result provides a &lsquo;mostly expanding&rsquo; counterpart to the work of De Simoi and Liverani, who treated such systems in the &lsquo;mostly contracting&rsquo; case (i.e., where there is one negative Lyapunov exponent).&lt;/p></div><div class="event_time">13:30 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 28</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"> Lycka Drakengren (ETH Zürich)</div><div class="event_title">Period map x product map = reduced <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We show that the fiber product of the period map t: M_g^(ct) -> A_g for curves and the product map A_(g_1) x ... x A_(g_k) -> A_g for any g = g_1 + ... + g_k is reduced. This opens up the possibility of calculating all pullbacks t^*[A_(g_1) x ... x A_(g_k)] in the Chow ring of M_g^(ct).</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_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"> Xi Chen (Universität Basel)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-xi-chen-universitaet-basel/">Title T.B.A.</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />TBA</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/geometry-seminar">Geometry Seminar</a></div><br /><div class="event_speaker"> Peter Feller (Université de Neuchâtel)</div><div class="event_title">Monodromies of non-fibered 3-manifolds <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />While compact oriented connected manifolds of dimension 1 (the circle and the interval) and 2 (genus <i>g</i> surfaces with <i>r</i> boundary components) are readily classified, the study of 3-manifolds is an active research area with many competing perspectives, including the celebrated geometrization program initiated by Thurston. Among 3-manifolds, the fibered ones&mdash;those with a regular map to the circle S<sup>1</sup>&mdash;are arguably the simplest to study, as their properties can be fully described in terms of their monodromy: the gluing self-map of the fiber (a surface) of a chosen regular map to S<sup>1</sup>. For example, irreducibility and atoroidality (the topological properties of not containing interesting spheres or tori) and hyperbolicity (the geometric property of featuring a metric with sectional curvature &ndash;1) are readily discerned from the properties of the monodromy. Famously, Thurston\'s hyperbolization criterion says a fibered 3-manifold is hyperbolic if and only if the monodromy is neither reducible nor periodic.<br>Based on joint work with Lewark&ndash;Orbegozo Rodriguez and Orbegozo Rodriguez, we describe how to associate a monodromy to any irreducible surface (a so-called Haken surface) &Sigma; in a 3-manifold that need not be a fiber of a regular map. Our setup is chosen to allow for an analog of Thurston\'s hyperbolization criterion. We illustrate our approach by providing new results concerning irreducibility, atoroidality and hyperbolicity for a particularly visualizable class of 3-manifolds: the exteriors of knots in the 3-sphere. In terms of technology, we use classical decomposition theory and the language of product discs and annuli as pioneered by Gabai to define a notion of monodromy that takes the form of a partially defined self-map of the arc and curve graph of &Sigma;.</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_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. Michael Multerer (USI Lugano)</div><div class="event_title">Data-intrinsic approximation in metric spaces <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Analysis and processing of data is a vital part of our modern society andrequires vast amounts of computational resources. To reduce the computationalburden, compressing and approximating data has become a central topic.We consider the approximation of labeled data samples, mathematicallydescribed as site-to-value maps between finite metric spaces. Within thissetting, we identify the discrete modulus of continuity as an effectivedata-intrinsic quantity to measure regularity of site-to-value maps withoutimposing further structural assumptions. We investigate the consistency of thediscrete modulus of continuity in the infinite data limit and propose analgorithm for its efficient computation. Building on these results, we presenta sample based approximation theory for labeled data. For data subject tostatistical uncertainty we consider multilevel approximation spaces and avariant of the multilevel Monte Carlo method to compute statistical quantitiesof interest. We provide extensive numerical studies to illustrate thefeasibility of the approach and to validate our theoretical results.</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_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"> Nikolay  Barashkov  (MPI Leipzig)</div><div class="event_title">\\Phi^4_3 as a Markov field <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Random Fields which posses the Markov Property have played an important role in the development of Constructive Field Theory. They are related to their relativistic counterparts through Nelson Reconstruction. In this talk I will describe an attempt to understand the Markov Property of the $\\Phi^4_3$ measure in 3 dimensions. We will also discuss the properties of its generator (i.e) the $\\Phi^4_3$ Hamiltonian. This is based on joint work with T. Gunaratnam.</div><div class="event_time">16:30 &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/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Prof. Dr. Jacopo Borga (MIT)</div><div class="event_title">Directed distance on bipolar-oriented triangulations: A path toward the directed Liouville quantum gravity metrics <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Last and first passage percolation in two dimensions are classical discrete models of random directed planar Euclidean metrics in the KPZ universality class. Their scaling limit is described by the directed landscape of Dauvergne-Ortmann-Virág.  Random planar maps are classical discrete models of random undirected planar fractal metrics in the LQG universality class. Their scaling limit is described by the (undirected) LQG metric of Ding-Dubédat-Dunlap-Falconet and Gwynne-Miller.  We present recent progress on the study of longest and shortest directed paths in the following natural model of directed random planar maps: the uniform infinite bipolar-oriented triangulation (UIBOT), which is the local limit of uniform bipolar-oriented triangulations around a typical edge and is expected to be in the LQG universality class with &gamma;=&Sqrt;4/3. We first explain the analogies between this model and last and first passage percolation. Then, we construct the Busemann function, which measures directed distance to infinity along a natural interface of the UIBOT. We show that, in the case of longest (resp. shortest) directed paths, this Busemann function converges in the scaling limit to a 2/3-stable Lévy process (resp. a 4/3-stable Lévy process). These results imply that in a typical subset of the UIBOT with n edges, longest directed path lengths are of order n^<sup>{3/4}</sup> and shortest directed path lengths are of order n^<sup>{3/8}</sup>.  We conclude the talk by explaining why these results fit into a program to construct the (longest and shortest) directed LQG metrics, two distinct two-parameter families of random fractal directed metrics which generalize the LQG metric and which could conceivably converge to the directed landscape upon taking an appropriate limit. Based on joint work with E. Gwynne.</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, December 18      </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"> Bo\'az Klartag (The Weizmann Institute of Science)</div><div class="event_title">Isoperimetric inequalities in high-dimensional convex sets</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://k-os.math.ethz.ch">[K-OS] Knot Online Seminar</a></div><br /><div class="event_speaker"> Robert E.  Gompf (University of Texas at Austin)</div><div class="event_title">Sections of maps from 4-manifolds to the 2-sphere; Unclassifiability of exotic R4\'s <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This talk will be a double-header. First we will discuss the examples from the above arXiv note (arXiv:2506.18066), singular fibrations over the sphere or disk which (perhaps surprisingly) have no sections. Then we will turn to the speaker\'s recent work with descriptive set theorist Aristotelis Panagiotopoulos, showing that, in a precise sense, exotic R<sup>4</sup>\'s are unclassifiable.</div><div class="event_time">16:15 &bull; <a class="external" href="https://u-paris.zoom.us/j/87853056962">online</a></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"> Bertrand Déroin (CNRS, Cergy Paris Université)</div><div class="event_title">Non left-orderability of irreducible lattices in semi-simple Lie groups of rank at least two <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 the question of left-orderability of lattices in semi-simple Lie groups, and explain that when the rank is at least two, such lattices are not left-orderable, a result obtained in collaboration with Sebastian Hurtado.</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://www.math.uzh.ch/mat675.1">PDE and Mathematical Physics</a></div><br /><div class="event_speaker">Carla Rubiliani (University of Tüingen)</div><div class="event_title">Information and Particle Propagation Bounds for Lattice Bosons Under Long-Range Interactions <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: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; display: inline !important; float: none;">In this talk, we explore locality properties of a Schr&ouml;dinger-type PDE describing the dynamics of a many-body bosonic system on a finite volume lattice. Such locality properties translate into two types of propagation bounds&lt;/span>&lt;br style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">&lt;br style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">&lt;span style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; display: inline !important; float: none;">1. Information propagation bounds (IPB) or Lieb-Robinson bounds, which control the dynamics of local operators.&lt;/span>&lt;br style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">&lt;span style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; display: inline !important; float: none;">2. Particle propagation bounds (PPB), which control the dynamics of particles through the lattice.&lt;/span>&lt;br style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">&lt;br style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">&lt;span style="caret-color: #000000; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; display: inline !important; float: none;">Although the PDE under consideration is linear, we have to face two mathematical challenges. First, the dimension of the underlying Hilbert space is very high and we want to derive bounds that thermodynamically stable, i.e. are uniform in such dimension. Second, bosonic interactions are unbounded in operator norm. Thanks to a multi-scale adaptation of the ASTLO ( adiabatic space-time localisation observables) method, which allows to remove the dependence of the error term on far away particles, we establish the first thermodynamically stable bosonic PPB for a class of long-range interactions. We were also able to control higher moments of the number operator. This opens the door to proving the first thermodynamically stable IPB for such bosonic systems. Establishing these bounds for bosonic systems is a long-standing open problem due to the lack of existing methods to control the unbounded nature of the bosonic operators when deriving &nbsp;IPB.&lt;/span>&lt;/p></div><div class="event_time">16:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.2</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, December 19      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_ba"><a class="external" href="https://unibas.ch">Universität Basel</a></div><div class="event_type"><a class="external" href="https://dmi.unibas.ch/de/forschung/mathematik/seminar-in-numerical-analysis">Seminar in Numerical Analysis</a></div><br /><div class="event_speaker"> Omar Lakkis (University of Sussex)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-in-numerical-analysis-omar-lakkis-university-of-sussex-2/">Adaptive methods and explicit time-stepping</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Aposteriori error analysis for Galerkin finite element methods have proven very successful tool in developing mathematically rigorous adaptive mesh refinement algorithms for implicit/space-time evolution equations. In this work we extend rigorous adaptivity principles to explicit time-stepping for the wave equation. I will review in the first part of the talk the state of the art for the wave equation. In the second part, I will present recent work in connection to fully practical explicit schemes such as the Leapfrog method and local time step variants thereof. This talk is mostly based on recent joint work with M Grote, C Santos and earlier work with EH Georgoulis, C Makridakis and J Virtanen. For further information about the seminar, please visit this webpage .</div><div class="event_time">11:00 &bull; Universität Basel, Room 05.001, Spiegelgasse 5, 4051 Basel</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>';