Prismatic F-Crystals and Wach Modules

Séminaire de géométrie arithmétique
For an absolutely unramified extension $K/mathbb{Q}_p$ with perfect residue field, by the works of Fontaine, Colmez, Wach and Berger, it is well known that the category of Wach modules over a certain integral period ring is equivalent to the category of lattices inside crystalline representations of $G_K$ (the absolute Galois group of $K$). Moreover, by the recent works of Bhatt and Scholze, we also know that lattices inside crystalline representations of $G_K$ are equivalent to the category of prismatic $F$-crystals on the absolute prismatic site of $O_K$, the ring of integers of $K$. The goal of this talk is to present a direct construction of the categorical equivalence between Wach modules and prismatic $F$-crystals over the absolute prismatic site of $O_K$. If time permits, we will also mention a natural generalisation of these results to the case of a « small » base ring and intended application (work in progress).
 
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Combinatorics and Arithmetic for Physics

Combinatorics and Arithmetic for PhysicsThe meeting focuses on questions of discrete mathematics and number theory, emphasizing computability. Problems are drawn mainly from theoretical physics: renormalization, combinatorial physics, geometry, evolution equations (commutative and noncommutative), or related to its models, but not only. Computations, based on combinatorial structures (graphs, trees, words, automata, semirings, bases), or classical structures (operators, Hopf algebras, evolution equations, special functions, categories) are good candidates for computer-based implementation and experimentation.
Organized by: Gérard H. E. DUCHAMP, Maxim KONTSEVICH, Gleb KOSHEVOY, Sergei NECHAEV, and Karol A. PENSON.
Speakers:

Nicolas Behr, CNRS, Université de Paris, IRIF
Joseph Ben Geloun, LIPN-Paris XIII
Lara Bossinger, IM UNAM, Oaxaca & IAS, Princeton
Marek Bozejko, Wroclaw University
Stéphane Dartois, Université Paris Saclay, CEA
Jehanne Dousse, Université de Genève
Gérard H.E. Duchamp, LIPN, Université Paris Nord
Vladimir Fock, IRMA, Strasbourg
Darij Grinberg, Drexel University
Dimitry Gurevich, IITP, Moscow
Yuki Kanakubo, Ibaraki University
Arthemy Kiselev, University of Groningen
Maxim Kontsevich, IHES
Gleb Koshevoy, IITP, Moscow
Toshiki Nakashima, Sophia University Tokyo
Mohamed Ouerfelli, Université Paris Saclay, CEA
Karol A. Penson, LPTMC, Sorbonne Université
Gleb Pogudin, LIX, Ecole polytechnique
Markus Reineke, Ruhr University Bochum
Ioannis Vlassopoulos, Athena Research Center
 

Sponsors: IHES – Math-STIC – LIPN (UMR-7030) – LPTMC (Univ-Paris 6) –  IJCLab, UMR Paris-Saclay/CNRS – INRIA – GDR EFI – CEA
Scientific Committee:Joseph Ben Geloun (LIPN-Paris XIII), Alin Bostan (INRIA), Marek Bozejko (Wroclaw University), Vincent Rivasseau (Orsay-CEA), Pierre Simonnet (Univ. Corse)

Representations, Probability, and Beyond: A Journey into Anatoly Vershik’s World

Representations, Probability, and Beyond: A Journey into Anatoly Vershik’s World Workshop in memory of A.M. Vershik
November 18-19, 2024, Mikhail Gromov (IHES & NYU), Sergei Nechaev (LPTMS Paris-Saclay) and Volodya Rubtsov (Univ. Angers) organize a two-day workshop devoted to the memory of Anatoly Vershik, who passed away earlier this year.
Anatoly Vershik (1933-2024) was a Russian mathematician who made important contributions in several fields of mathematics. In particular, he is renowned for his joint work with Sergei V. Kerov on the theory of representations of infinite symmetric groups and on applications of the longest strictly increasing subsuite problem in group theory. 
 
 
Invited Speakers:

Alexander BARVINOK (Univ. of Michigan)
Alexey BORODIN (MIT)
Alexander CHERVOV (Institut Curie)
Anna ERSCHLER (Sorbonne Univ.)
Sergey FOMIN (Univ. of Michigan)
Mikhail GROMOV (IHES & NYU)
Vadim KAIMANOVICH (Univ. of Ottawa)
Andrey MALYUTIN (St. Petersburg State Univ.)
Tatiana NAGNIBEDA (Univ. Genève)
Sergei NECHAEV (LPTMS Paris-Saclay)
Andrey OKOUNKOV (Princeton Univ.)
Grigorii OLSHANSKII (IITP, Moscow)
Leonid PASTUR (King’s College London)
Fyodor PETROV (St. Petersburg State Univ.)
Volodya RUBTSOV (Univ. d’Angers)
Natalia TSILEVICH (Bar Ilan University)

 

A Sharp Lower Bound on the Small Eigenvalues of Surfaces

Probability and analysis informal seminar
The Laplacian is a central operator in the analysis of surfaces (and life in general). In this talk, we investigate how small its small eigenvalues can be, giving a sharp, quadratic bound on the k-th eigenvalue of a surface in terms of k, the surface’s genus g, and its global geometry via the injectivity radius. The techniques involve extremal length, spectral embedding, and volume arguments.Joint work with Guy Lachman and Asaf Nachmias, based on the paper: https://arxiv.org/abs/2407.21780For an exposition and overview of the paper, see here:

New paper on arXiv: A sharp lower bound on the eigenvalues of surfaces


 
 
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An introduction to examples of SL_2(R)

An introduction to examples of SL2(R) – invariant subvarieties V of the moduli space of holomorphic 1-forms, Omega Mg , and their connections to topology, Hodge theory and algebraic geometry.

Introduction of translation surfaces and their moduli spaces

Introduction of translation surfaces (definitions and examples) and their moduli spaces, period coordinates, SL(2,R)-action (examples: pseudo-Anosov), Kontsevich-Zorich cocycle (examples of concrete matrices via Thurston-Veech and/or Rauzy-Veech algorithm), some applications (of Zorich phenomenon in Delecroix-Hubert-Lelievre and of Lyapunov exponents in Kappes-Moeller).

Etude de problèmes paraboliques « forward-backward » et application aux bulles de recirculation dans les couches limites

Séminaire Laurent Schwartz — EDP et applications
 

Disproving the Deift Conjecture: the Loss of Almost Periodicity

Séminaire Laurent Schwartz — EDP et applications
 

Stability of Rayleigh-Jeans Equilibria in the Kinetic FPUT Equation

Séminaire Laurent Schwartz — EDP et applications
 

Principalization and Resolution on Foliated Manifolds

The work discussed is joint with André Belotto da Silva, Michael Temkin and Jaroslaw Wlodarczyk.
Given a subvariety X of a nonsingular complex variety Y carrying a monomial foliation F, we construct an embedded resolution of singularities of X that is aligned with the foliation F, solving a problem of Belotto da Silva. This in particular implies resolution of singularities of singular integrable foliations.
 
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A New Approach to the Cutoff Phenomenon

Probability and analysis informal seminar
The cutoff phenomenon is an abrupt transition from out of equilibrium to equilibrium undergoned by certain Markov processes in the limit where the number of states tends to infinity. Discovered forty years ago in the context of card shuffling, it has since then been established in a variety of contexts, including random walks on graphs and groups, high-temperature spin systems, or interacting particles. Nevertheless, a general theory is still missing, and identifying the general mechanisms underlying this mysterious phenomenon remains one of the most fundamental problems in the area of mixing times. In this talk, I will give a self-contained introduction to this fascinating question, and then describe a new approach based on entropy and curvature.
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A Survey of Teichmüller Curves

A Teichmüller curve V in Mg is an isometrically immersed algebraic curve in the moduli space of Riemann surfaces. These rare, extremal objects lie at the nexus of algebraic geometry, number theory, complex analysis and surface topology. We will discuss some ideas behind the known constructions of Teichmüller curves that have been discovered over the past 30 years, and a selection of open problems.