**UM Math Graduate Students Seminar**

Dr. Drew Armstrong

* University of Miami *

**will present**

**What is ADE? **

Friday, September 20, 2013, 2:30pm

Ungar Building Room 402

**Abstract:** Many deep classification problems in mathematics come down to the following: Find all triples of positive integers p,q,r such that 1/p+1/q+1/r is greater than 1. Exercise: What does this problem have to do with the attached diagram? In this talk I will explain the linear algebra phenomenon that underlies all such classifications. It is mysterious in a good way.