Hi Nullset, we hope you all had a great summer. Normally, we’d hope you had an amazing summer, but we know that you didn’t. Why? Because it was missing something important: Math Colloquia! Fear not, because the time has come for our first Math Colloquia of the school year!

We will be featuring Professor McConnell from the math department; topic of the talk TBA. Does Professor McConnell’s name sound familiar? He may or may not be the person who McConnell Hall is named after.

Who? **Professor Mark McConnell**

What? **An Algorithm for Hecke Operators**

When? **Wednesday, October 2 at 4:30**

Where? **Fine Room 214**

Food? **Your choice of BOBA and BYOS**

Abstract: A lattice is a discrete subgroup of R^n isomorphic to Z^n. In the plane, where n=2, the square lattice and the honeycomb are familiar examples. The space of all lattices can be studied via the *well-rounded retract* for SL_n, which is a complex glued together from topological cells. When n=2, the well-rounded retract is a tree with three edges meeting each vertex. Hecke operators act on the cohomology H^i of these spaces, and their eigenvalues are important in number theory. Previous algorithms to compute Hecke operators have worked for all n, but only in a narrow range of i depending on n. The talk will present a 2016 algorithm of Robert MacPherson and myself that works for SL_n for all n and all i. The talk will not assume any detailed background in topology or cohomology.

If you have any further questions, please let us know!

We hope to see you there!

Your academic chairs, Nathan and Tristan