Skip to content
# Events for September 21, 2018 from General and Seminar calendars

## IAMCS Event - Workshop on Quantum Computation and Information

**Description:** Event Link

## Mathematical Physics and Harmonic Analysis Seminar

**Abstract:** In this talk, we shall review basic concepts related to the mathematics and physics of PT symmetry and non-self-adjoint eigenvalue problems. We shall also discuss recent activities in the newly emerging field of PT symmetric and reverse space-time integrable nonlocal models.

## Working Seminar in Groups, Dynamics, and Operator Algebras

## Algebra and Combinatorics Seminar

**Abstract:** The famous Four Color Theorem states that every graph that can be drawn in the plane without edge-crossing is properly 4-colorable, which means that one can color its vertices with 4 colors such that every pair of adjacent vertices receive different colors. It is equivalent to say that every graph that does not contain a subgraph contractible to K_5 or K_{3,3} is properly 4-colorable. Hadwiger in 1943 proposed a far generalization of the Four Color Theorem: every graph that does not contain a subgraph contractible to K_{t+1} is properly t-colorable. Hajos, and Gerards and Seymour, respectively, proposed two strengthening of Hadwiger's conjecture, where only special kinds of edges are allowed to be contracted. More precisely, these three conjectures state that every graph that does no contain K_{t+1} as a minor (topological minor, or odd minor, respectively) is properly t-colorable. These three conjectures are either open or false, except for some very small t. One weakening of these three conjectures is to color the vertices such that every monochromatic component has bounded size, which is called clustered coloring. In this talk we will show joint work with David Wood about a series of tight results about clustered coloring on graphs with no subgraph isomorphic to a fixed complete bipartite graph. These results have a number of applications, including nearly optimal or first linear bound for the number of colors on the clustered coloring version of the previous three conjectures, as well as results on graphs embeddable in a surface of bounded genus where edge-crossings are allowed. No background about graph theory is required for this talk.

## Promotion Talk - Professor Riad Masri

**Description:**

**Location:** Rudder 701

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

**Location:** BLOC 628

**Speaker:** Ziad Musslimani, Florida State University

**Title:** *PT symmetry, nonlocal integrable models and physical applications*

**Time:** 2:00PM - 2:50PM

**Location:** BLOC 506A

**Speaker:** Xin Ma, Texas A&M University

**Title:** *Topological full groups of one-sided shifts of finite type III*

**Time:** 3:00PM - 4:00PM

**Location:** BLOC 628

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

**Title:** *Clustered coloring on old graph coloring conjectures*

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

**Location:** BLOC 220

**Speaker:** Professor Riad Masri, Texas A&M University

Title: The Chowla-Selberg formula

Abstract:

In the 1940's, Chowla and Selberg discovered an identity relating values of Dedekind's eta function at algebraic numbers to values of the Gamma function at rational numbers. This identity, now called the Chowla-Selberg formula, has since played an important role in number theory. In this talk, I will describe the Chowla-Selberg formula, and explain how it can be generalized to higher-dimensions.