# PhD Course: Expander graphs (first meeting)

**Time: **
Mon 2022-09-12 13.15 - 15.00

**Location: **
Albano, Building 1, Cramér room

**Participating: **
Sven Raum

This is the first meeting for the PhD course on expander graphs. For more information, see the course webpage .

Overview:

Expanders are sequences of graphs that in various respects are highly connect, though have a limited number of edges. This intuition can be expressed in various ways, using mixing times of random walks, eigenvalues of combinatorial Laplace operators or geometric measures of connectedness such as the Cheeger constant. The subject draws its relevance among others from applications to computer science as well as its connections to representation theory and geometric group theory.

The aim of this course is to understand the equivalence of various formulations of expanders, construct examples and discuss some of their applications in and outside of mathematics.