Applied Math Colloquium

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For more information, contact Laurent Demanet

Spring 2026

Spring semester 4:30pm-5:30pm in room number 2-190

Date Speaker Abstract
February 09 (Monday)

Joel A. Tropp
(California Institute of Technology)

Positive random walks and positive-semidefinite random matrices

Abstract: On the real line, a random walk that can only move in the positive direction is very unlikely to remain close to its origin. After a fixed number of steps, the left tail has a Gaussian profile under minimal assumptions. Remarkably, the same phenomenon occurs when we consider a positive random walk on the cone of positive-semidefinite matrices. After a fixed number of steps, the minimum eigenvalue is described by a Gaussian random matrix model.

This talk introduces a new way to make this intuition rigorous. The methodology addresses an open problem in computational mathematics about sparse random embeddings. The presentation is targeted at a general mathematical audience.

Preprint:  https://arxiv.org/abs/2501.16578

March 12 at 12 PM in CCSE, Bldg 45

Kui Ren
(Columbia University)

April 09

Shayan Oveis Gharan
(University of Washington)

April 16 at 12 PM in CCSE, Bldg 45

Leslie Greengard
(Flatiron, New York University)