Speaker: Sian Fryer

Title: Totally Nonnegative Matrices

Abstract:A totally positive real matrix is one for which every minor is positive. As with people, total positivity in matrices can get a bit boring after a while, so we turn our attention to something a bit less demanding: total nonnegativity, i.e. each minor is nonnegative. This talk will give an introduction to total nonnegativity in real matrices and the real Grassmannian, and describe how we can get some really nice combinatorics out of this deceptively simple definition.