# Events for 10/11/2019 from all calendars

## Mathematical Physics and Harmonic Analysis Seminar

**Time:** 1:50PM - 2:50PM

**Location:** BLOC 628

**Speaker:** Irina Holmes, Texas A&M University

**Title:** *A new proof of the weak (1,1) inequality for the dyadic square function*

**Abstract:** This project (joint with Paata Ivanisvili and Sasha Volberg) is concerned with finding the (strange) sharp constant in the weak (1,1) inequality for the dyadic square function, using the Bellman function method. This constant was conjectured by Bollobas in the 1980’s and proved first by Osekowski using Brownian motion methods. The interesting aspect of our new proof is that it required the invention of a new way to work with Bellman functions - a way which we hope can be implemented in other problems.

## Student/Postdoc Working Geometry Seminar

**Time:** 2:00PM - 3:00PM

**Location:** BLOC 624

**Speaker:** A. Harper, TAMU

**Title:** *BB apolarity con'td*

## Algebra and Combinatorics Seminar

**Time:** 3:00PM - 3:00PM

**Location:** BLOC 628

**Speaker:** Chun-Hung Liu, Texas A&M University

**Title:** *Length of cycles in non-sparse graphs*

**Abstract:** Intuitively, "dense" graphs contain any "desired substructure". In this talk, we will use a unified tool to prove few conjectures and open questions proposed since 1980s with this flavor, where the "desired substructure" is a set of cycles whose lengths satisfy certain conditions. They include two conjectures of Thomassen about minimum degree, a conjecture of Dean about connectivity, a conjecture of Sudakov and Verstraete about chromatic number, and an optimal answer of a question of Bondy and Vince about minimum degree. Joint work with Jun Gao, Qingyi Huo and Jie Ma.

## Geometry Seminar

**Time:** 4:00PM - 5:00PM

**Location:** BLOC 628

**Speaker:** Taylor Brysiewicz, Texas A&M University

**Title:** *The degree of Stiefel manifolds and spaces of Parseval frames.*

**Abstract:** The (k, n)-th Stiefel manifold is the space of k×n matrices M with the property that M*M^T=Id. Equivalently, this is the space of Parseval n-frames for k-dimensional space. The polynomial equations characterizing the Stiefel manifold define an embedded affine algebraic variety. We will sketch our proof of a formula for its degree using aspects of representation theory, Gelfand-Tsetlin polytopes, and the combinatorics of non-intersecting lattice paths. [joint work with Fulvio Gesmundo]