The geometry of numbers

Speaker: Brian Conrad
Title: The geometry of numbers
Abstract: A method due to Minkowski solves certain kind of number-theoretic problems by
using the geometry of lattices in Euclidean space. We explain some of the
basic geometric ideas, and as an application show how to prove that every positive integer is
a sum of four perfect squares by using the formula for the volume of a
solid ball in 4-dimensional space.