var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-67"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-65"><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. 9</span>      <span style="float: right; text-align:right; width: 250px;">17.4 - 21.4.2023</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Spring Semester 2023</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, April 17      </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/studium/mathematik/doktorat/bernoullis-tafelrunde">Bernoullis Tafelrunde</a></div><br /><div class="event_speaker"> Martin Ramm (Universität Basel)</div><div class="event_title">Introduction to Full Waveform Inversion <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The inverse scattering problem is the task of recovering the interior of an object,called the medium, based on how waves are scattered when passing through themedium, and appears frequently in different disciplines. One approach for solvingthis problem is full waveform inversion (FWI), an algorithm originally developedin geophysics for imaging the interior of the earth using scattering data generatedby seismic waves. In this talk, I will use a one-dimensional example to explain thisalgorithm.</div><div class="event_time">12:15 &bull; Universität Basel, Spiegelgasse 5, SR 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="http://www.iaa.tu-bs.de/konmerz/gausseminar/">GAuS Seminar</a></div><br /><div class="event_speaker">Dr. Jinyeop Lee (Ludwig-Maximilians-Universität München)</div><div class="event_title">On the characterisation of fragmented Bose-Einstein condensation and  its emergent effective evolution <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Fragmented Bose-Einstein condensates are large systems of identical bosons displaying multiple macroscopic occupations of one-body states, in a suitable sense. The quest for an effective dynamics of the fragmented condensate at the leading order in the number of particles, in analogy to the much more controlled scenario for complete condensation in one single state, is deceptive both because characterising fragmentation solely in terms of reduced density matrices is unsatisfactory and ambiguous, and because as soon as the time evolution starts the rank of the reduced marginals generically passes from finite to infinite, which is a signature of a transfer of occupations on infinitely many more one-body states. In this work we review these difficulties, we refine previous characterisations of fragmented condensates in terms of marginals, and we provide a quantitative rate of convergence to the leading effective dynamics in the double limit of infinitely many particles and infinite energy gap. This is a joint work with Alessandro Michelangeli.</div><div class="event_time">13:00 &bull; Online via Zoom</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/mat770.1">Oberseminar: Algebraische Geometrie</a></div><br /><div class="event_speaker">Dr. Emanuel Reinecke (Max Planck Institute for Mathematics)</div><div class="event_title">Unipotent homotopy theory of schemes <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In this talk, I will present a notion of unipotent homotopy theory for schemes, which is based on Toen\'s work on affine stacks. I will discuss some general properties of the resulting unipotent homotopy group schemes and explain how over a field of characteristic p>0, they often recover the unipotent completion of the Nori fundamental group scheme, p-adic etale homotopy groups, and Artin-Mazur formal groups. As examples, we will see computations in the case of curves, abelian varieties, and Calabi-Yau varieties. Joint work with Shubhodip Mondal.</div><div class="event_time">13:15 &bull; UZH Irchel, Winterthurerstrasse 190, Z&uuml;rich, Building Y27, Room H 25</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, April 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"> Karoly Böröczky (Alfréd Rényi Institute of Mathematics)</div><div class="event_title">The Isoperimetric inequality, the Brunn-Minkowski theory, and the Lp Minkowski problem</div><div class="event_time">10:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external_nolink">Talks in Mathematical Finance </a></div><br /><div class="event_speaker"> Puneet Pasricha (EPF Lausanne)</div><div class="event_title">Empirical Asset Pricing via Ensemble Gaussian Process Regression <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We introduce an ensemble learning method based on Gaussian Process Regression (GPR) for predicting conditional expected stock returns given stock-level and macro-economic information. Our ensemble learning approach significantly reduces the computational complexity inherent in GPR inference and takes into account the non-stationarity of the financial data. We conduct an empirical analysis on a large cross-section of US stocks from 1962 to 2016. Our method dominates existing machine learning models statistically and economically. Exploiting the Bayesian nature of GPR, we introduce the mean-variance optimal portfolio with respect to the predictive uncertainty distribution. It significantly dominates standard prediction-sorted portfolios and the S&P 500.&lt;brAuthors: Damir Filipovic (EPFL) and Puneet Pasricha (EPFL)</div><div class="event_time">12:30 &bull; EPF Lausanne, UniL campus, Extranef 125</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker"><a class="external" href="https://cypaquette.github.io/">Prof. Dr. Courtney Paquette (McGill, Canada)</a></div><div class="event_title">DACO-FDS: Stochastic Algorithms in the Large: Batch Size Saturation, Stepsize Criticality, Generalization Performance, and Exact Dynamics (Part I) <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 framework for analyzing dynamics of stochastic optimization algorithms (e.g., stochastic gradient descent (SGD) and momentum (SGD+M)) when both the number of samples and dimensions are large. For the analysis, we will introduce a stochastic differential equation, called homogenized SGD. We show that homogenized SGD is the high-dimensional equivalent of SGD -- for any quadratic statistic (e.g., population risk with quadratic loss), the statistic under the iterates of SGD converges to the statistic under homogenized SGD when the number of samples n and number of features d are polynomially related. By analyzing homogenized SGD, we provide exact non-asymptotic high-dimensional expressions for the training dynamics and generalization performance of SGD in terms of a solution of a Volterra integral equation. The analysis is formulated for data matrices and target vectors that satisfy a family of resolvent conditions, which can roughly be viewed as a weak form of delocalization of sample-side singular vectors of the data. By analyzing these limiting dynamics, we can provide insights into learning rate, momentum parameter, and batch size selection. For instance, we identify a stability measurement, the implicit conditioning ratio (ICR), which regulates the ability of SGD+M to accelerate the algorithm. When the batch size exceeds this ICR, SGD+M converges linearly at a rate of $O(1/ \\kappa)$, matching optimal full-batch momentum (in particular performing as well as a full-batch but with a fraction of the size). For batch sizes smaller than the ICR, in contrast, SGD+M has rates that scale like a multiple of the single batch SGD rate. We give explicit choices for the learning rate and momentum parameter in terms of the Hessian spectra that achieve this performance. Finally we show this model matches performances on real data sets. </div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sfs/news-and-events/data-science-seminar">ETH-FDS seminar </a></div><br /><div class="event_speaker"> Courtney Paquette (McGill University, Canada)</div><div class="event_title">DACO-&#8203;FDS: Stochastic Algorithms in the Large: Batch Size Saturation, Stepsize Criticality, Generalization Performance, and Exact Dynamics (Part I) <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />	Random matrices frequently appear in many different fields — physics, computer science, applied and pure mathematics. Oftentimes the random matrix of interest will have non-&#8203;trivial structure — entries that are dependent and have potentially different means and variances (e.g. sparse Wigner matrices, matrices corresponding to adjacencies of random graphs, sample covariance matrices). However, current understanding of such complex random matrices remains lacking. In this talk, I will discuss recent results concerning the spectrum of sums of independent random matrices with a.s. bounded operator norms. In particular, I will demonstrate that under some fairly general conditions, such sums will exhibit the following universality phenomenon — their spectrum will lie close to that of a Gaussian random matrix with the same mean and covariance. No prior background in random matrix theory is required — basic knowledge of probability and linear algebra are sufficient. (joint with Ramon van Handel) Pre-&#8203;print link: https://web.math.princeton.edu/~rvan/tuniv220113.pdf</div><div class="event_time">14:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/daco-seminar">DACO Seminar</a></div><br /><div class="event_speaker"><a class="external" href="https://elliotpaquette.github.io/">Prof. Dr. Elliot Paquette (McGill, Canada)</a></div><div class="event_title">DACO-FDS: Stochastic Algorithms in the Large: Batch Size Saturation, Stepsize Criticality, Generalization Performance, and Exact Dynamics (Part II) <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 framework for analyzing dynamics of stochastic optimization algorithms (e.g., stochastic gradient descent (SGD) and momentum (SGD+M)) when both the number of samples and dimensions are large. For the analysis, we will introduce a stochastic differential equation, called homogenized SGD. We show that homogenized SGD is the high-dimensional equivalent of SGD -- for any quadratic statistic (e.g., population risk with quadratic loss), the statistic under the iterates of SGD converges to the statistic under homogenized SGD when the number of samples n and number of features d are polynomially related. By analyzing homogenized SGD, we provide exact non-asymptotic high-dimensional expressions for the training dynamics and generalization performance of SGD in terms of a solution of a Volterra integral equation. The analysis is formulated for data matrices and target vectors that satisfy a family of resolvent conditions, which can roughly be viewed as a weak form of delocalization of sample-side singular vectors of the data. By analyzing these limiting dynamics, we can provide insights into learning rate, momentum parameter, and batch size selection. For instance, we identify a stability measurement, the implicit conditioning ratio (ICR), which regulates the ability of SGD+M to accelerate the algorithm. When the batch size exceeds this ICR, SGD+M converges linearly at a rate of $O(1/ \\kappa)$, matching optimal full-batch momentum (in particular performing as well as a full-batch but with a fraction of the size). For batch sizes smaller than the ICR, in contrast, SGD+M has rates that scale like a multiple of the single batch SGD rate. We give explicit choices for the learning rate and momentum parameter in terms of the Hessian spectra that achieve this performance. Finally we show this model matches performances on real data sets. </div><div class="event_time">15:10 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/sfs/news-and-events/data-science-seminar">ETH-FDS seminar </a></div><br /><div class="event_speaker"> Elliot  Paquette (McGill University, Canada)</div><div class="event_title">DACO-&#8203;FDS: Stochastic Algorithms in the Large: Batch Size Saturation, Stepsize Criticality, Generalization Performance, and Exact Dynamics (Part II) <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 framework for analyzing dynamics of stochastic optimization algorithms (e.g., stochastic gradient descent (SGD) and momentum (SGD+M)) when both the number of samples and dimensions are large. For the analysis, we will introduce a stochastic differential equation, called homogenized SGD. We show that homogenized SGD is the high-&#8203;dimensional equivalent of SGD -- for any quadratic statistic (e.g., population risk with quadratic loss), the statistic under the iterates of SGD converges to the statistic under homogenized SGD when the number of samples n and number of features d are polynomially related. By analyzing homogenized SGD, we provide exact non-&#8203;asymptotic high-&#8203;dimensional expressions for the training dynamics and generalization performance of SGD in terms of a solution of a Volterra integral equation. The analysis is formulated for data matrices and target vectors that satisfy a family of resolvent conditions, which can roughly be viewed as a weak form of delocalization of sample-&#8203;side singular vectors of the data. By analyzing these limiting dynamics, we can provide insights into learning rate, momentum parameter, and batch size selection. For instance, we identify a stability measurement, the implicit conditioning ratio (ICR), which regulates the ability of SGD+M to accelerate the algorithm. When the batch size exceeds this ICR, SGD+M converges linearly at a rate of $O(1/ \\kappa)$, matching optimal full-&#8203;batch momentum (in particular performing as well as a full-&#8203;batch but with a fraction of the size). For batch sizes smaller than the ICR, in contrast, SGD+M has rates that scale like a multiple of the single batch SGD rate. We give explicit choices for the learning rate and momentum parameter in terms of the Hessian spectra that achieve this performance. Finally we show this model matches performances on real data sets.</div><div class="event_time">15:10 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 19.1</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker">Dr. Mateus Sousa (BCAM )</div><div class="event_title">Sharp embeddings between weighted Paley–Wiener spaces  <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 discuss some extremal problems related to embeddings between weighted Paley–Wiener spaces. We will present some asymptotic results for sharp constants in terms of the parameters involved, deduce existence results for extremal functions as well as radial symmetry of those. For certain cases, these extremal problems can be reformulated in terms of sharp Poincaré inequalities, and for those cases we will present a characterisation of extremizers and sharp constants that recover several classical results.</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_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"> Patricio Almirón (IMAG)</div><div class="event_title">The underlying topological nature of the Poincaré series of a plane curve <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In 2003, Campillo, Delgado and Gusein-Zade show the equality between the Poincaré series of a reducible plane curve singularity $C$ and the Alexander polynomial $\\Delta_L$ of the corresponding link $L$. However, their proof lacks of a conceptual explanation for this coincidence. In this talk I will show some new theorems of factorization of the Poincaré series $P_C$ depending on some key values of the semigroup of values of $C$ with purely algebraic methods. As a consequence of these theorems, we will show that our procedure supplies a new proof of the theorem of Campillo, Delgado and Gusein-Zade. More concretely, we will focus on the translation of our algebraic construction to the iterated toric structure of the link $L$. This is a joint work with Julio José Moyano-Fernández.</div><div class="event_time">15:15 &bull; EPF Lausanne, Salle MA A3 30</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"> Francesco Bonechi  (Università di Firenze)</div><div class="event_title">Towards equivariant Yang-Mills theory  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />A general formalism for dealing with the equivariant extensions of the solution of the Classical Master Equation in the Batalin-Vilkovisky geometry is presented. As usual, the AKSZ construction gives a class of particularly simple and relevant examples. The BV pushforward is a procedure introduced by A. Losev that frames in the BV context the idea of Wilson renormalization in QFT that defines the effective action by integrating over the ultraviolet fields. I will discuss how it adapts to the equivariant case and discuss the example of the Donaldson-Witten theory in four dimensions and its relation with Yang-Mills theory. This talk is based on papers written in collaboration with A. Cattaneo, J. Qiu and M. Zabzine.</div><div class="event_time">16:30 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_fr"><a class="external" href="https://www.unifr.ch">Université de Fribourg</a></div><div class="event_type"><a class="external" href="https://www.unifr.ch/math/de/info/kolloquium.html">Colloquium </a></div><br /><div class="event_speaker">Prof. Dr. Augusto Gerolin (Canada Research Chair & University of Ottawa)</div><div class="event_title">An optimal transport viewpoint on Density Functional Theory for Strongly Correlated systems <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Density Functional Theory (DFT) is the standard approach to quantum chemistry in simulations with more than a dozen electrons or so. The classical way of breaking the curse of dimensionality in DFT is through the Kohn-Sham (KS) formalism, which has been extremely successful in predicting properties in materials science, chemistry and biochemistry. Despite its enormous success, KS DFT approximations fail in accurately predicting the physics of systems in which electronic correlation plays a prominent role (e.g. transition metals, which are the workhorse of catalysis) and dispersion (van der Walls) interactions (e.g. hydrogen-bonding interaction in the DNA). <br>In this talk, I will tell part of that story by introducing mathematical and computational aspects of DFT from a multi-marginal optimal transport perspective. Particular emphasis will be given on rigorous mathematical results and challenges in the field. The talk has few prerequisites and (definitely) no contraindications.Therefore, Master and Ph.D. students in physics, theoretical chemistry and mathematics are encouraged to attend as well.</div><div class="event_time">17:15 &bull; Université de Fribourg, room Phys 2.52</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, April 19      </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"> Shahar Mendelson (The Australian National University)</div><div class="event_title">Probabilistic methods in Analysis</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/forschung/mathematik/analysis/analysis-seminar">Analysis Seminar</a></div><br /><div class="event_speaker"> Stefano Spirito (Università degli Studi dell\'Aquila)</div><div class="event_title">On the Kelvin-Voigt model for Viscoelastic material <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will review the existence and uniqueness theory of a model for viscoelastic materials of Kelvin-Voigt type with large strain. In particular, I will first review the existence theory in L2, and then show that also propagation of H1-regularity for the deformation gradient of weak solutions in two and three dimensions holds.  Moreover, in two dimensions it is also possible to prove uniqueness of weak solutions. Additional propagation of higher regularity can be obtained, leading to a global in time existence of smooth solutions. Joint work with K. Koumatos (U. of Sussex), C. Lattanzio (UnivAQ) and A. Tzavaras (KAUST).</div><div class="event_time">14:15 &bull; Universität Basel, Spiegelgasse 5, SR 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"> Michael Borinsky (ITS)</div><div class="event_title">On the amount of top-weight cohomology in the moduli space of curves <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />I will present new results on the asymptotic growth rate of the Euler characteristic of Kontsevich\'s commutative graph complex. By a work of Chan, Galatius and Payne, these results imply the same asymptotic growth rate for the top-weight Euler characteristic of M_g, the moduli space of curves, and establish the existence of large amounts of unexplained top-weight cohomology in this space. I will illustrate the ingredients for the proof and comment on related recent work with Karen Vogtmann on Out(F_n) and the moduli space of graphs.</div><div class="event_time">15:45 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://uzh.ch">Universit&auml;t Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/seminar-on-stochastic-processes">Seminar on Stochastic Processes</a></div><br /><div class="event_speaker">Prof. Dr. Elliot Paquette (Department of Mathematics and Statistics, McGill University)</div><div class="event_title">The random matrix Fyodorov-Hiary-Keating conjecture <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Fyodorov-Hiary-Keating conjecture has two parts, one in random matrix theory and one about the Riemann zeta function. In the random matrix part, it gives the precise distributional limit for the maximum of a characteristic polynomial of a Haar Unitary matrix. Using the replica method and a physically motivated `freezing’ ansatz, they derived one of the most precise log-correlated field predictions todate, and they did it for a process which was not even Gaussian. While existing work shows that Haar Unitary matrices had many log correlated field connections, techniques for showing convergence of the maximum typically rely on either the Gaussianity of the underlying process or precise branching structures built into the problem; the characteristic polynomial has neither. We will describe the problem and the current state of the art, in which we (the speaker and Ofer Zeitouni) show the convergence in law of the maximum of a Circular-beta ensemble random matrix to a convolution of a gumbel and the total mass of a (non-Gaussian) critical multiplicative chaos.</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 20      </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"> Brita Nucinkis (Royal Holloway, University of London)</div><div class="event_title">Cohomological methods in group theory</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_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">Dr. Ran Tamir (ETH Zuerich)</div><div class="event_title">On entropy-rate bounds and two problems in Gaussian database models <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This talk has two independent parts. In the first part of my talk, I will discuss entropy-rates of integer-valued time-series. Originated in information theory as a measure of compressibility, the entropy-rate has been suggested in various studies as a measure of the unpredictability of a given model. While the entropy-rate is well defined for a general stationary time-series, its calculation may be a complicated task, especially in models with relatively large or infinite alphabets. I will present two new upper bounds on entropy-rates of integer-valued time-series, which rely merely on the second-order statistics of the model at hand. In the second part of my talk, I will discuss two related problems concerning Gaussian database models, namely hypothesis testing and alignment recovery. While these two problems have been separately treated in recent studies, I will present a low complexity algorithm that solves them as a joint problem. Theoretical guarantees on the various error probabilities will be provided, and if time permits, I will present some proof ideas.</div><div class="event_time">12:15 &bull; Universität Bern, IMSV, Alpeneggstrasse 22, 3012 Bern, Hörraum -203</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"> Sam Molcho (ETH Zürich)</div><div class="event_title">Jacobians, Stable Maps, and Cycles on the Moduli Space of Curves <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The cohomology ring of the moduli space of curves contains two families of classes with different geometric origins: one comes from the universal Jacobian and Brill-Noether theory, and the other from the moduli space of stable maps and Gromov-Witten theory. After reviewing their construction, I will explain how new ideas from logarithmic geometry connect these classes, and discuss how the connection allows us to explicitly calculate them in the tautological ring, in terms of its standard generators. Time permitting, I will indicate the implications these calculations have for the study of relations in the tautological ring. The talk will draw from several joint works and some work in progress, carried out with Holmes-Pandharipande-Pixton-Schmitt, Abreu-Pagani, Ranganthan, and Wise.   </div><div class="event_time">13:15 &bull; EPF Lausanne, Salle MA A3 30</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://www.ntwebseminar.org/">Number Theory Web Seminar</a></div><br /><div class="event_speaker"> Bjorn Poonen (MIT)</div><div class="event_title">Integral points on curves via Baker\'s method and finite étale covers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We prove results in the direction of showing that for some affine curves, Baker\'s method applied to finite étale covers is insufficient to determine the integral points.</div><div class="event_time">15:00 &bull; Universität Basel, online Seminar</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-mathematical-physics">Talks in Mathematical Physics</a></div><br /><div class="event_speaker"> Alexander Veselov (Loughborough University)</div><div class="event_title">Complex cobordisms, theta divisors and permutohedra <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />It was known since 1960s (Novikov, Mischenko) that the logarithm of the formal group in complex cobordisms can be written explicitly in terms of the complex projective spaces, but the algebro-geometric nature of the coefficients of the corresponding exponential was not clear until recently. In the talk I will explain that the answer can be given by the smooth theta divisors of principally polarised abelian varieties.It will be shown that the topological characteristics of the theta divisors and their intersections can be expressed in terms of the combinatorics of permutohedra. We reveal also interesting relations between the theta divisors, permutohedral varieties and Tomei manifolds from the Toda lattice theory.The talk is based on joint work with V.M. Buchstaber.</div><div class="event_time">15:15 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G 43</div>        </div>        <div class="day_content_item normal"><div class="event_location uni_zh"><a class="external" href="https://ethz.ch">ETH Z&uuml;rich</a></div><div class="event_type"><a class="external" href="https://math.ethz.ch/s/talks-in-financial-and-insurance-mathematics">Talks in Financial and Insurance Mathematics</a></div><br /><div class="event_speaker"><a class="external" href="https://fam.tuwien.ac.at/~jeisenbe/">Prof. Dr. Julia Eisenberg (Vienna University of Technology)</a></div><div class="event_title">On Some Multi-Regime (and even beyond) Optimisation Problems in Non-Life Insurance <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We consider a company who models the dependence of its surplus - a Brownian motion with drift - on business cycles by a Markov chain.Depending on the chosen target functional and the impact of the control on the surplus, the value function and the optimal strategy can be found explicitly, recursively or not at all. The constant "once and forever" strategies, optimal for the case of only one state, turn out to be suboptimal in most multi-state problems. In this talk, we consider some "explicit"- and "recursive"-solution cases. As a pudding, we look at the "beyond" case, where the model features a stochastic continuous discounting rate - an infinite-regime setting.</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 21      </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_nolink">Talks in Mathematical Finance </a></div><br /><div class="event_speaker"> Dimitris Papanikolaou (ellogg School of Management)</div><div class="event_title">Who Bears the Cost of Aggregate Fluctuations and Why? <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Recessions are typically associated with lower firm cashflows and higher discount rates. We show that these two components have very different implications for labor income growth.Higher discount rates lead to lower worker earnings for workers at the bottom of the income distribution; these declines are primarily driven by job separations. By contrast, lower cashflow (Or productivity) news is followed by declines in earnings for workers at the top of the income distribution, with most of the effect coming from the intensive margin. We build an equilibrium model of labor market search that quantitatively replicates these facts. The model matches several stylized features of the data: the level of unemployment volatility with procyclical job finding rates and countercyclical job destruction rates; countercyclical tail risk in labor income growth; the low level of cyclicality of the average wage; the U-shaped sensitivity of worker earnings to aggregate output by prior income; and the cyclical evolution of income inequality.</div><div class="event_time">10:30 &bull; EPF Lausanne, UniL campus, Extranef 126</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/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 least squares Hessian/Gradient recovery method for fully nonlinear PDEs in Hamilton–Jacobi–Bellman form (joint work wit Amireh Mousavi) <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Least-squares finite element recovery-based methods provide a simple and practical way to approximate linear elliptic PDEs in nondivergence form where standard variational approach either fails or requires technically complex modifications.<br>This idea allows the creation of efficient solvers for fully nonlinear elliptic equations, the linearization of which leaves us with an equation in nondivergence form. An important class of fully nonlinear elliptic PDEs can be written in Hamilton--Jacobi--Bellman (Dynamic Programming) form, i.e., as the supremum of a collection of linear operators acting on the unkown.<br>The least-squares FEM approach, a variant of the nonvariational finite element method, is based on gradient or Hessian recovery and allows the use of FEMs of arbitrary degree. The price to pay for using higher order FEMs is the loss of discrete-level monotonicity (maximum principle), which is valid for the PDE and crucial in proving the convergence of many degree one FEM and finite difference schemes.<br>Suitable functional spaces and penalties in the least-squares\'s cost functional must be carefully crafted in order to ensure stability and convergence of the scheme with a good approximation of the gradient (or Hessian) under the Cordes condition on the family of linear operators being optimized.<br>Furthermore, the nonlinear operator which is not necessarily everywhere differentiable, must be linearized in appropriate functional spaces using semismooth Newton or Howard\'s policy iteration method. A crucial contribution of our work, is the proof of convergence of the semismooth Newton method at the continuum level, i.e., on infinite dimesional functionals spaces. This allows an easy use of our non-monotone schemes which provides convergence rates as well as a posteriori error estimates.</div><div class="event_time">11:00 &bull; Universität Basel, Spiegelgasse 5, SR 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://www.math.uzh.ch/mat760">Ergodic theory and dynamical systems seminar</a></div><br /><div class="event_speaker">Dr. Frank Trujillo (Universität Zürich)</div><div class="event_title">On invariant measures of circle maps with breaks <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />By a classical theorem of Denjoy, any sufficiently regular piece-wise smooth circle homeomorphism with finitely many branches (often called a circle homeomorphism with breaks) and irrational rotation number is topologically conjugated to an irrational circle rotation. In particular, it admits a unique invariant probability measure. We will discuss dimensional properties of this measure and show that, generically, this unique invariant probability measure has zero Hausdorff dimension. To encode this generic condition, we consider piece-wise smooth homeomorphisms as generalized interval exchange transformations of the interval and rely on the notion of combinatorial rotation number.</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_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"> Luis Martinez-Zoroa (ICMAT, Madrid)</div><div class="event_title">Instantaneous loss of regularity for SQG with fractional diffusion <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />The Surface quasi-geostrophic (SQG) equation is an important active scalar model, both due to its shared properties with 3D Euler as well as for its applications to model certain atmospherical phenomena. It has already been established that instantaneous loss of regularity can occur in the inviscid case in certain Sobolev spaces, but it is unclear at what point the diffusion prevents this phenomenon from happening . In this talk I will discuss the behaviour when there is some super-critical fractional diffusion.</div><div class="event_time">14:15 &bull; EPF Lausanne, Salle CM 1 113</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>';