A solution to Weaver's \(KS_2\)

We will outline the proof that gives a positive solution of to Weaver's conjecture \(KS_2\). That is, we will show that any isotropic collection of vectors whose outer products sum to twice the identity can be partitioned into two parts such that each part is a small distance from the identity. The distance will depend on the maximum length of the vectors in the collection but not the dimension (the two requirements necessary for Weaver's reduction to a solution of Kadison Singer). This will include introducing a new technique for establishing the existence of certain combinatorial objects that we call the "Method of Interlacing Polynomials."

This talk is intended to be accessible by a general mathematics audience, and represents joint work with Dan Spielman and Nikhil Srivastava.



Yale University