Independence, moments, and the stable homology of moduli spaces

Speaker: 

Sean Howe

Institution: 

University of Utah

Time: 

Thursday, November 13, 2025 - 4:00pm to 5:00pm

Host: 

Location: 

RH 306

What is the second moment of a random smooth plane curve?  Is the multiset of eigenvalues of a random orthogonal matrix a Gaussian random variable? Is a random compact Riemann surface a Poisson process? In this talk, I will describe a categorified version of probability theory that makes these nonsense questions into precise mathematics and give some applications to the topology and arithmetic of moduli spaces in algebraic geometry. 

Taking big steps and going nowhere: how to moonwalk back from infinity

Speaker: 

Nicolas Monod

Institution: 

EPFL, Switzerland

Time: 

Thursday, October 23, 2025 - 4:00pm

Host: 

Location: 

RH 306

I will tell a story around a theorem we proved with Tom Hutchcroft and Omer Tamuz. In one version of the story, we look for fixed-point theorems in the spirit of Markov-Kakutani but for several maps at the same time.

In the other version, we cross out items from a finite list and we ask: is there a random list that would almost not change at all when we cross out any of the first few items?

We solve these questions, which are really only one question, by performing what looks like a backwards random walk in which every step would be infinitely long, but stationary.

Dance and Mathematics

Speaker: 

Reggie Wilson and Jesse Wolfson

Institution: 

Fist and Heel Performance Group

Time: 

Thursday, May 22, 2025 - 5:00pm to 6:00pm

Host: 

Location: 

ISEB 1010

In this public talk, internationally acclaimed choreographer Reggie Wilson and math professor Jesse Wolfson will describe their decade+ collaboration exploring what math can do for dance and what dance can do for math.

Entropy of (quantum) entanglement in pure states of rapid decorrelation

Speaker: 

Michael Aizenman

Institution: 

Princeton University

Time: 

Friday, April 25, 2025 - 3:00pm to 4:00pm

Location: 

NS 1201

I.  The entropy of the restriction of a pure quantum state to a subsystem is a measure of the entanglement between the system's two components.   

II.  After explaining the concepts, the talk will focus on conditions implying an area-type bound on the entanglement in pure states of quantum lattice models.

Almost Orthogonality in Fourier Analysis: From Singular integrals, to Function Spaces, to Leibniz Rules for Fractional Derivatives

Speaker: 

Rodolfo H. Torres

Institution: 

University of California, Riverside

Time: 

Thursday, May 1, 2025 - 4:00pm to 4:50pm

Host: 

Location: 

RH 306

Fourier analysis has been an extraordinarily powerful mathematical tool since its development 200 years ago, and currently has a wide range of applications in diverse scientific fields including digital image processing, forensics, option pricing, cryptography, optics, oceanography, and protein structure analysis. Like a prism that decomposes a beam of light into a rainbow of colors, Fourier analysis transforms signals into a mathematical spectrum of basic wave components of different amplitudes and frequencies, from which many hidden properties in the data can be deciphered. At the abstract mathematical level signals are represented by functions and their filtering and other operations on them by operators. From a functional analytical point of view, these objects are studied by decomposing them into elementary building blocks, some of which have wavelike behavior too. Decomposition techniques such as atomic, molecular, wavelet and wave-packet expansions provide a multi-scale refinement of Fourier analysis and exploit a rather simple concept: "waves with very different frequencies are almost invisible to each other". Many of these useful techniques have been developed around the study of some particular operators called singular integral operators and,  recently, similar techniques have been pushed to the analysis of new multilinear operators that arise in the study of (para) product-like operations, null-forms, and other nonlinear functional expressions. In this talk we will present some of our contributions in the study of multilinear singular integrals and function spaces, and their applications to the development of the equivalent of the calculus Leibniz rule to the concept of fractional derivatives.
 

Arithmetic aspects of plane curves

Speaker: 

Kirsten Wickelgren

Institution: 

Duke University

Time: 

Thursday, October 16, 2025 - 4:00pm to 5:00pm

Host: 

Location: 

RH 306

There is a unique line through 2 points in the plane, and a unique conic through 5. These counts generalize to a count of degree d rational curves in the plane passing through 3d-1 points. Surprisingly, the problem of determining these numbers is connected to mathematical physics, and it was not until the 1990's that it was completely solved. For example, Kontsevich determined them with a celebrated recursive formula. Such formulas are valid when you allow your curves to be defined with complex coefficients.  Some of the solutions may be real, or integral, or defined over Q[i], but the fixed count does not see the difference. Homotopy theory on the other hand, studies continuous deformations of maps. In its modern form, it provides a framework to study shape in many contexts, including the motivic homotopy of algebraic varieties. This talk will introduce some interactions of homotopy theory with the arithmetic of solutions to enumerative problems in geometry. We will use this to completely determine an enriched "count" of degree d rational curves passing through 3d-1 points over an arbitrary field of characteristic not 2 or 3. This enumeration is joint work with Erwan Brugallé and Johannes Rau.

Moduli spaces in tropical geometry

Speaker: 

Melody Chan

Institution: 

Brown University

Time: 

Thursday, April 24, 2025 - 4:00pm to 5:00pm

Host: 

Location: 

RH 306

I intend to give a true introduction, accessible to beginning graduate students, to the topics in the title: what is tropical geometry? What is a moduli space? And how can one be used to study the other?  Then I'll discuss some aspects of joint work with Francis Brown, Søren Galatius, and Sam Payne, in which we identify a Hopf algebraic structure on the weight 0 subspace of the compactly supported cohomology of the moduli space of abelian varieties and deduce a number of consequences. 

The Fractional Calderón Problem

Speaker: 

Gunther Uhlmann

Institution: 

University of Washington

Time: 

Thursday, February 20, 2025 - 4:00pm to 4:50pm

Location: 

RH 306

The famous Calderón problem consists in determining the conductivity of a medium by making voltage and current measurements at
the boundary. We consider in this talk a nonlocal analog of this problem. Nonlocal operators arise in many situations where long term
interactions play a role.  The fractional Laplace is a prototype of a nonlocal operator. We will survey some of the main results on inverse problems associated with the fractional Laplacian showing that the nonlocality helps for the inverse problems.

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