The University of Illinois Algebra-Geometry-Combinatorics Seminar
Spring 2024, Time: Thursdays 3-3:50PM, Place: Burrill Hall 124 / Altgeld Hall 345

Geometric central limit theorems on non-smooth spaces, Ezra Miller (Duke University) -- April 25th, 2024, 2:30pm in Altgeld 245 (Department Colloquium)

The central limit theorem (CLT) is commonly thought of as occurring on the real line, or in multivariate form on a real vector space. Motivated by statistical applications involving nonlinear data, such as angles or phylogenetic trees, the past twenty years have seen CLTs proved for Fr├ęchet means on manifolds and on certain examples of singular spaces built from flat pieces glued together in combinatorial ways. These CLTs reduce to the linear case by tangent space approximation or by gluing. What should a CLT look like on general non-smooth spaces, where tangent spaces are not linear and no combinatorial gluing or flat pieces are available? Answering this question involves figuring out appropriate classes of spaces and measures, correct analogues of Gaussian random variables, how the geometry of the space (think "curvature") is reflected in the limiting distribution, and generally how the geometry of sampling from measures on singular spaces behaves. This talk provides an overview of these answers, starting with a review of the usual linear CLT and its generalization to smooth manifolds, viewed through a lens that casts the singular CLT as a natural outgrowth, and concluding with how this investigation opens gateways to further advances in geometric probability, topology, and statistics. Joint work with Jonathan Mattingly and Do Tran.

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The seminar co-organizers are Ian Cavey, Andrew Hardt, Shiliang Gao, Elizabeth Kelley, and Alexander Yong.