# Events for 09/30/2019 from all calendars

## Michael Brannan Promotion Talk

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

**Location:** BLOC 220

**Speaker:** Michael Brannan Promotion Talk, Texas A&M University

**Description:**

.TITLE: Graphs, non-local games, and quantum symmetry groups.

ABSTRACT:A well-known theorem of Lov\'asz says that two finite graphs X and Y are isomorphic if and only if for each graph H, the number of graph homomorphisms from H to X equals the number of graph homomorphisms from H to Y. In this talk, we will consider the following question: What happens if we only ask that the number of homomorphisms from H to X and the number of homomorphisms from H to Y be equal for planar graphs H? I will explain how this planar relaxation of graph isomorphism admits two remarkably different interpretations in terms of (1) the theory of non-local games from quantum information theory, and (2) the algebraic notion of a quantum symmetry group of a graph. I will explain how these two very different perspectives on the same idea can be exploited to construct graphs whose quantum symmetry groups have interesting operator algebraic properties.