Mon, 12 Jun 2023

16:00 - 17:00
L1

Fourier transform as a triangular matrix

George Lusztig
(MIT)
Abstract

Let $V$ be a finite dimensional vector space over the field with two elements with a given nondegenerate symplectic form. Let $[V]$ be the vector space of complex valued functions on $V$ and let $[V]_{\mathbb Z}$ be the subgroup of $[V]$ consisting of integer valued functions. We show that there exists a Z-basis of $[V]_{\mathbb Z}$ consisting of characteristic functions of certain explicit isotropic subspaces of $V$ such that the matrix of the Fourier transform from $[V]$ to $[V]$ with respect to this basis is triangular. This continues the tradition started by Hermite who described eigenvectors for the Fourier transform over real numbers.

Mon, 12 Jun 2023

16:30 - 17:30
L4

Breaking glass optimally and Minkowski's problem for polytopes

Jian-Guo Liu
(Duke University)
Abstract
Motivated by a study of least-action incompressible flows, we study all the ways that a given convex body in Euclidean space can break into countably many pieces that move away from each other rigidly at constant velocity, following geodesic motions in the sense of optimal transport theory. These we classify in terms of a countable version of Minkowski's geometric problem of determining convex polytopes by their face areas and normals. Illustrations involve various intriguing examples both fractal and paradoxical, including Apollonian packings and other types of full packings by smooth balls.
Degenerate Cahn-Hilliard systems: From nonlocal to local
Carrillo, J Elbar, C Skrzeczkowski, J Communications in Contemporary Mathematics (20 Jun 2024) http://arxiv.org/abs/2303.11929v1
Polynomial bounds for chromatic number VIII. Excluding a path and a
complete multipartite graph
Nguyen, T Scott, A Seymour, P (21 Mar 2023) http://arxiv.org/abs/2303.11766v1
Compressed sensing of low-rank plus sparse matrices
Tanner, J Vary, S Applied and Computational Harmonic Analysis volume 64 254-293 (May 2023)
Principled interpolation of Green's functions learned from data
Praveen, H Boullé, N Earls, C Computer Methods in Applied Mechanics and Engineering volume 409 (01 May 2023)
Optimal cross-border electricity trading
Cartea, Á Flora, M Vargiolu, T Slavov, G SIAM Journal on Financial Mathematics volume 13 issue 1 262 (14 Mar 2022)
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