var sms = '<div id="sms_bulletin">  <div id="sms_header">  <div class="do_not_print" id="arrow_left"><a href="?next=-14"><img src="//www2.math.ethz.ch/smsjs/images/arrow_left.png"/></a></div><div class="do_not_print" id="arrow_right"><a href="?next=-12"><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. 5</span>      <span style="float: right; text-align:right; width: 250px;">20.1 - 24.1.2025</span>      <span style="text-align: center; display: block; width: 250px; margin: auto; position: relative;">Winter Break 2024/25</span>    </div>  </div>  <div></div>  <div id="sms_content">    <div class="day">      <div class="day_title">        Monday, January 20      </div>      <div class="day_content">        <div class="day_content_item normal"><div class="event_location uni_la"><a class="external" href="https://www.epfl.ch">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/schools/sb/research/math/events/mathematics-colloquia/">Mathematics Colloquium </a></div><br /><div class="event_speaker"> Joel A. Tropp</div><div class="event_title">Positive random walks and positive-semidefinite random matrices <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />On the real line, a random walk that can only move in the positivedirection is very unlikely to remain close to its starting point. Aftera fixed number of steps, the left tail has a Gaussian profile, underminimal assumptions. Remarkably, the same phenomenon occurs when weconsider a positive random walk on the cone of positive-semidefinitematrices. After a fixed number of steps, the minimum eigenvalue is alsodescribed by a Gaussian model.This talk introduces a new way to make this intuition rigorous. Themethodology provides the solution to an open problem in computationalmathematics about sparse random embeddings. The presentation is targeted at a general mathematical audience.</div><div class="event_time">13:30 &bull; EPF Lausanne, auditoriumELA1</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"> David  Ginsbourger (University of Bern)</div><div class="event_title">Title T.B.A.</div><div class="event_time">14:00 &bull; EPF Lausanne, Extranef 125</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Tuesday, January 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" href="https://theory.epfl.ch/seminar/">Theory and Combinatorics Seminar</a></div><br /><div class="event_speaker">  Duri Andrea  Janett</div><div class="event_title"> Truly Supercritical Trade-offs for Resolution, Cutting Planes, Monotone Circuits, and Weisfeiler--Leman <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We exhibit supercritical trade-off for monotone circuits, showing thatthere are functions computable by small circuits for which any circuitmust have depth super-linear or even super-polynomial in the number ofvariables, far exceeding the linear worst-case upper bound. We obtainsimilar trade-offs in proof complexity, where we establish the firstsize-depth trade-offs for cutting planes and resolution that are trulysupercritical, i.e., in terms of formula size rather than number ofvariables, and we also show supercritical trade-offs between width andsize for treelike resolution.Our results build on a new supercritical depth-width trade-off forresolution, obtained by refining and strengthening the compressionscheme for the Cop-Robber game in [Grohe, Lichter, Neuen & Schweitzer2023]. This yields robust supercritical trade-offs for dimension versusiteration number in the Weisfeiler--Leman algorithm. Our other resultsfollow from improved lifting theorems that might be of independent interest.This is joint work with Susanna F. de Rezende, Noah Fleming, JakobNordström and Shuo Pang.</div><div class="event_time">11:00 &bull; EPF Lausanne, INJ114</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"> Dominique  Manchon (CNRS et Université Clermont-Auvergne)</div><div class="event_title">Post-groupes et algèbres post-Lie : une introduction  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />Le algèbres post-Lie sont apparues en 2007 dans un article de B. Vallette sur l\'homologie des posets de partitions, et indépendemment, sous une forme légèrement différente, dans un travail de H. Munthe-Kaas et W. Wright sur la résolution numérique d\'équations différentielles sur un espace homogène. La notion récente de post-groupe 2023) est équivalente à deux notions plus anciennement établies : les groupes à deux étages ou skew-braces (2017) et les groupes tressés (2000). Elle est étroitement lie aux algèbres post-Lie, en ce sens que l\'algèbre de Lie d\'un post-groupe de Lie est une algèbre post-Lie.Je ferai un survol de ces notions, avant d\'aborder quelques résultats récemment obtenus avec M. J. H. Al-Kaabi, K. Ebrahimi-Fard, H. Munthe-Kaas et Lorenzo Zambotti.</div><div class="event_time">14:00 &bull; Université de Genève, Conseil Général 7-9, Room 1-05</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Wednesday, January 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://math.ethz.ch/s/algebraic-geometry-and-moduli-seminar">Algebraic Geometry and Moduli Seminar</a></div><br /><div class="event_speaker">Prof. Dr. Pierrick Bousseau (Univ. of Georgia)</div><div class="event_title">Non-toric brane webs, Calabi-Yau 3-folds, and 5d SCFTs <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />One of the most remarkable predictions of string/M-theory is the existence of 5-dimensional superconformal field theories (5d SCFTs). There are two main approaches for constructing these 5d SCFTs, using either M-theory on canonical 3-fold singularities, or intersecting branes in Type IIB string theory. A natural question is to compare these two approaches. The answer is well-known for webs of 5-branes in Type IIB string theory, where the M-theory dual canonical 3-fold singularity is a toric Calabi–Yau 3-fold.  In this talk,  building on recent advances in mirror symmetry and enumerative geometry, I will provide an answer for the more general case of webs of 5-branes with 7-branes and explain how to construct the M-theory dual non-toric Calabi-Yau 3-fold. This is joint work with Valery Alexeev and Hulya Arguz.</div><div class="event_time">13:30 &bull; ETH Zentrum, R&auml;mistrasse 101, Z&uuml;rich, Building HG, Room G G43</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"> Kwan Woo (Seoul National University)</div><div class="event_title"><a class="external" href="https://dmi.unibas.ch/de/news-events/detail/seminar-analysis-and-mathematical-physics-kwan-woo-seoul-national-university/">Regularity Properties of Linear Drift-Diffusion Equations</a> <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />We investigate linear elliptic and parabolic equations with drifts, commonly referred to as drift-diffusion equations. Specifically, the drift term (the first-order coefficient) is assumed to belong to critical Lebesgue spaces. We discuss the integrability and boundedness properties of solutions to these equations.</div><div class="event_time">14:15 &bull; Universität Basel, Alte Universität - Seminarraum -201</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Thursday, January 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">EPF Lausanne</a></div><div class="event_type"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/seminar/epfl-topology-seminar-fall-2024/">Séminaire de Topologie </a></div><br /><div class="event_speaker"> Léonard Guetta (Utrecht University)</div><div class="event_title"><a class="external" href="https://www.epfl.ch/labs/hessbellwald-lab/seminar/epfl-topology-seminar-fall-2024/">A Double Categorical Model of (&#8734;,1)-Categories</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, I will present recent joint work with Lyne Moser (arXiv:2412.15715), in which we prove that the category of double categories can be equipped with a model category structure which is related, via a zig-zag of Quillen equivalences, to the Rezk model structure on simplicial spaces. In particular, with this model structure, the category of double categories serves as a model for the homotopy theory of (&#8734;,1)-categories.Along with sketching the proof of this theorem, I will highlight some notable features of this model of (&#8734;,1)-categories, such as the ability to compute homotopy colimits in a very explicit and straightforward manner. Time permitting, I will also discuss some conjectural applications of this result to future projects.</div><div class="event_time">14:15 &bull; <a class="external" href="https://plan.epfl.ch/?room==MA%20B1%20524">EPF Lausanne</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://memento.epfl.ch/MATHS/?period=14">Computational Mathematics Seminar </a></div><br /><div class="event_speaker"> Léonard  Guetta (Utrecht University)</div><div class="event_title">A Double Categorical Model of (&#8734;,1)-Categories <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 recent joint work with Lyne Moser (arXiv:2412.15715), in which we prove that the category of double categories can be equipped with a model category structure which is related, via a zig-zag of Quillen equivalences, to the Rezk model structure on simplicial spaces. In particular, with this model structure, the category of double categories serves as a model for the homotopy theory of (&#8734;,1)-categories.Along with sketching the proof of this theorem, I will highlight some notable features of this model of (&#8734;,1)-categories, such as the ability to compute homotopy colimits in a very explicit and straightforward manner. Time permitting, I will also discuss some conjectural applications of this result to future projects.</div><div class="event_time">14:15 &bull; EPF Lausanne, MA B1 524</div>        </div>      </div>    </div>    <div class="day">      <div class="day_title">        Friday, January 24      </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"> João Tiago  Fernandes Rocha</div><div class="event_title">1.5-Approximation Using the Cut LP for the Weighted Tree Augmentation Problem <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />n the weighted tree augmentation problem (WTAP) we try to augment aspanning tree T of a graph G=(V,E) at a minimum-cost to achieve2-edge-connectivity. This problem, while fundamental in network design,is NP-complete. In this work, we examine WTAP through the lens of linearprogramming (LP) by looking at what is known as the cut LP and using adual approach. Previous works have set the integrality gap between 1.5and 2. Our work aims at settling the integrality gap at 1.5. This is apresentation of ongoing work in collaboration with Marina Drygala.</div><div class="event_time">11:00 &bull; EPF Lausanne, INJ114</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"> Mohammed  Lemou (CNRS/IRMAR, Rennes)</div><div class="event_title">Fully Homomorphic Encryption (FHE) on large integers <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />This presentation focuses on a protocol for homomorphic encryption of large integers that integrates the encoding of their moduli using the Chinese Remainder Theorem (CRT) along with a TFHE-like encryption scheme designed for small messages. Within the framework of fully homomorphic encryption on the torus, we explore various algebraic tools that are crucial for managing polynomials in power prime cyclotomic contexts, including procedures for packing, extraction, and bootstrapping.</div><div class="event_time">13:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</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"> Philippe  Chartier (INRIA/IRMAR, Rennes)</div><div class="event_title">Homomorphic sign evaluation with a RNS representation of integers  <span class="abstract-button do_not_print">abstract</span></div><div class="abstract-text" style="display: none"><strong>Abstract:</strong><br />In the context of fully-homomorphic-encryption, we consider the representation of large integers by their decomposition over a product of rings (through the Chinese Remainder Theorem) and introduce a new algorithm for the determination of the sign solely through the knowledge of ring-components. Our implementation with 128 bits of security delivers a correct result with a probability higher than 1-1.e-12 in less than 140 milliseconds for 32-bit integers on a laptop.</div><div class="event_time">14:15 &bull; Université de Genève, Conseil Général 7-9, Room 1-07</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>';