### GEORGE MASON
UNIVERSITY

DEPARTMENT OF MATHEMATICAL
SCIENCES

COLLOQUIUM

OCTOBER 19, 2018

**Speaker: **
Ilesanmi Adeboye, Wesleyan University

**Title: ***
Lower bounds for the covolume of lattices of semi-simple Lie groups
*

**Abstract: **
A classic theorem of Kazhdan and Margulis states that for any semi-simple Lie group without compact factors, there is a positive lower bound on the co-volume of lattices. A direct consequence is a positive minimum volume for orbifolds modeled on the corresponding symmetric space. In this talk, I will construct an improved upper bound for the sectional curvature of a semi-simple Lie group. I will also show how H. C. Wangâ€™s quantitative analysis of the Kazhdan-Margulis result can be extended to the exceptional Lie groups. These elements will then be used to establish a uniform lower bound for arbitrary orbifold quotients of symmetric spaces of non-compact type.

**Time:** Friday, October 19, 2018, 3:30-4:20 p.m.

**Place:** Exploratory Hall, room 4106

**Refreshments** will be served at 3:00 p.m.

Department of Mathematical Sciences

George Mason University

4400 University Drive, MS 3F2

Fairfax, VA 22030-4444

http://math.gmu.edu/

Tel. 703-993-1460, Fax. 703-993-1491