Title: On the isoperimetric profile of the hypercube  Abstract: The isoperimetric problem in the hypercube is a strikingly simple topic which is not yet completely understood. We will review the known facts on the problem, focusing on how the gaussian isoperimetric inequality provides a lower bound for the isoperimetric profile of the hypercube.We will exploit this […]
Title: Fibered Yoneda Lemma in Lean 4 Abstract: In this talk, I would like to give you a sense of what it’s like to do category theory in a computer. I use an interactive theorem prover called Lean4, a complex piece of software based on dependent type theory. In the first part, I will give a quick […]
Title:Â From Instability to Singularity Formation in Incompressible FluidsAbstract:Â In this talk, I will first review the singularity formation problem in incompressible fluid dynamics, describing how particle transport poses the main challenge in constructing blow-up solutions for the 3d incompressible Euler equations. I will then outline a new mechanism that allows us to overcome the effects of […]
Title: The Geometry of Theta Correspondence for Principal Series over Finite Fields Abstract: In this talk, we explore the finite field theta correspondence between principal series representations. We begin by categorifying the relevant Hecke algebra bimodules associated with this correspondence. Utilizing characteristic cycle maps, we provide a detailed description of the theta correspondence for principal […]
Title: ell-adic topological Jacquet-Langlands duality  Abstract: I will describe the construction of an "ell-adic topological Jacquet-Langlands (TJL) dual" of each finite CW-complex. One effect of the TJL dual is that the representations of the Morava stabilizer group, which arise in the height n Morava E-theory of a finite spectrum X, get turned into continuous […]
Infinite dimensional representations of semisimple Lie algebras
Title: Mean curvature flow with multiplicity 2 convergence Abstract: Mean curvature flow (MCF) has been widely studied in recent decades, and higher multiplicity convergence is an important topic in the study of MCF. In this talk, we present two examples of immortal MCF in R^3 and S^n x , which converge to a plane and a […]
Title: The integral converse theorem and no-shadowing bounds for polynomials and L-functions Abstract: I will outline an alternative argument for the complex-analytic ingredient of the "unbounded denominators theorem" joint with Frank Calegari and Yunqing Tang, and then a refinement of the result as a converse theorem for Dirichlet series with almost-integer coefficients. This is followed […]
Title: On linear and non-linear stability of collisionless systems on black hole exteriors.  Abstract:  I will present upcoming linear and non-linear stability results for collisionless systems on spherically symmetric black holes. On the one hand, I will discuss the decay properties of massive Vlasov fields on the exterior of Schwarzschild spacetime. On the other hand, I will discuss […]
Title: Constructing (infinity,n)-categories with desired properties Abstract: In this talk I want to describe a specific example of a symmetric monoidal (infinity,3)-category of generalized spans with local systems (a la Haugseng) where the local systems compose with a push-pull formula similar to the Fourier-Mukai transform of algebraic geometry. The motivation comes from physics and functorial […]
Title: Three theorems about asymptotic expansions of harmonic functions at the boundaryAbstract: Consider a harmonic function on a domain, vanishing along a part of its boundary, and a point on that part of the boundary which is asymptotically conical. I will explain that under a very mild notion of "asymptotically conical," the harmonic function has […]
Title:Â On the generalized Beauville decomposition.Abstract:Â Over 30 years ago, the work of Beauville and Deninger-Murre endowed the cohomology of an abelian scheme a (motivic) decomposition which splits the Leray filtration. This structure, now known as the Beauville decomposition, is induced by algebraic cycles obtained from the Fourier-Mukai coherent duality. In recent years, the study of Hitchin […]
Title: Calculus of fractions for quasicategories Abstract: A central object of interest in abstract homotopy theory is the localization of marked categories. One case of interest is when the marked category admits a "calculus of fractions". This condition was introduced by P. Gabriel and M. Zisman to construct better-behaved models for the localization. For instance, […]
Title: Computer Assisted Proof of Finite Time Singularity of the 3D Euler Equations Abstract: Whether the 3D incompressible Navier-Stokes equations can develop a finite time singularity from smooth initial data is one of the most challenging problems in nonlinear PDEs. In the first talk, we will present some new numerical evidence that the 3D Navier-Stokes […]
Title: Torsion vanishing for some Shimura varietiesAbstract:Â We will discuss joint work with Linus Hamann on generalizing the torsion-vanishing results of Caraiani-Scholze and Koshikawa for the cohomology of Shimura varieties. We do this by applying various geometric methods to understand sheaves on Bun_G, the moduli stack of G-bundles on the Fargues-Fontaine curve. Our method showcases that […]
Title: What is an automorphic representation? Abstract: Andrew Wiles' famous proof of Fermat's last theorem was crucially based on constructing a mysterious connection between two classes of mathematical objects: "modular forms" and "elliptic curves". However, if you try looking up what a modular form actually is, you'll find an elementary but very unmotivated definition involving functions on […]
Title: Boundary behavior of the Allen-Cahn equation and the construction of free boundary minimal hypersurfacesAbstract: In the late 70s, the work of Modica, Mortola, De Giorgi, and many others established deep connections between the Allen-Cahn equation, a semi-linear elliptic equation arising in the van der Waals-Cahn-Hilliard theory of phase transitions, and minimal hypersurfaces, i.e. critical […]
Title: Isotrivial fibrations of hyper-Kähler manifolds.Abstract: A Lagrangian fibration of a projective hyper-Kähler manifold is called isotrivial if its smooth (abelian variety) fibers are all isomorphic to each other. Given an isotrivial fibration of a HK manifold f : X -> B with at least one rational section, we prove the following four descriptions of the fibration: […]
Title: Twisted Gan-Gross-Prasad conjecture and arithmetic fundamental lemma Abstract: The twisted Gan-Gross-Prasad (GGP) conjecture opens a way of studying (a twist of) central Asai L-values via descents and period integrals. Firstly, I will prove new cases of twisted GGP conjecture (joint work with Weixiao Lu and Danielle Wang), based on the relative trace formula approach […]
Abstract Plancherel formula & Harish-Chandra Schwartz space
A Brief Introduction to Gödel's Incompleteness Theorems In 1931 Kurt Gödel proved a pair of landmark results that limited the strength of formal theories of mathematics. These "incompleteness theorems" are central to modern understandings of logic, and also to numerous misunderstandings. So today, we'll explore these theorems - how they work, how they were developed […]
Title: Soap films, Plateau's laws, and the Allen-Cahn equation Abstract: Plateau's problem of minimizing area among surfaces with a common boundary is the basic model for soap films and leads to the theory of minimal surfaces. In this talk we will discuss a modification of Plateau's problem in which surfaces are replaced with regions of small […]
Title:Â Finite approximations as a tool for studying triangulated categories.Abstract:Â A metric on a category assigns lengths to morphisms, with the triangle inequality holding. This notion goes back to a 1974 article by Lawvere. We'll start with a quick review of some basic constructions, like forming the Cauchy completion of a category with respect to a metric.And […]
Title: On an application of the residue method. Abstract: When a period integral of an automorphic form converges and is not zero it is often related to a special value of an L-function and indicates that the automorphic form is a functorial transfer. When convergence fails it is still interesting to make sense of the […]
Title: Kähler-Einstein metric, K-stability and moduli of Fano varieties I. Abstract: A complex variety with a positive first Chern class is called a Fano variety. The question of whether a Fano variety has a Kähler-Einstein metric has been a major topic in complex geometry since the 1980s. The Yau-Tian-Donaldson Conjecture predicts the existence of such […]
Title: Kähler-Einstein metric, K-stability and moduli of Fano varieties II. Abstract: Algebraic varieties are given by solutions of a system of polynomial equations. Constructing parameter space for them has roots in many different fields, e.g. number theory, complex analysis, mathematical physics etc. It is often related to stability notions. The first framework to construct moduli […]