## Upcoming conferences & activities

- Conference on 4-manifolds and knot concordance (Mon, 17 Oct 2016 - Fri, 21 Oct 2016)
- Hirzebruch Lecture 2016 by Günter Ziegler (Wed, 02 Nov 2016)
- Conference for Young researchers in homotopy theory and categorical structures February 13-15, 2017 (Mon, 13 Feb 2017 - Wed, 15 Feb 2017)
- Young Women in Geometry (Mon, 03 Apr 2017 - Wed, 05 Apr 2017)
- Modular Forms are everywhere (Mon, 15 May 2017 - Fri, 26 May 2017)

## Interview with PhD student Danylo Radchenko on solving the sphere packing problem in dimension 24

Danylo Radchenko, PhD student at the Max Planck Institute for Mathematics and the Bonn International Graduate School for Mathematics, on the famous sphere packing problem, his contribution to the proof in dimension 24, and on being a PhD student in Bonn.

**You are co-author of a paper about the sphere packaging problem in dimension 24. Let’s start from the scratch: What’s the sphere packing problem about?**

This problem goes way back to 1611 when Johannes Kepler discussed the question how to stack cannon balls most efficiently. He found the answer, but he couldn’t prove it. This is why it’s called the “Kepler conjecture”. Since then, physicists have been working with his solution. But for mathematicians it’s not enough to know the answer, we also have to find a way to deduce logically why it is indeed correct. The solution is actually pretty simple. Almost everyone will find it intuitively if you give them a bunch of balls and some time. But the mathematical proof of this is highly complex. Even for a normal three dimensional room, the proof was found only in 1998 by Thomas Hales.

## Geordie Williamson to Receive 2016 Clay Research Award

**Geordie Williamson**, advanced researcher at the Max Planck Institute for Mathematics in Bonn will be awarded the 2016 Clay Research Award in recognition of his groundbreaking work in representation theory and related fields.

In particular, the award recognises two major breakthroughs. First, his proof, with Ben Elias, of Soergel’s conjecture on bimodules associated to Coxeter groups. This established the combinatorial result that the coefficients of the Kazhdan-Lusztig polynomials are non-negative, as well as yielding a new proof of Kazhdan and Lusztig’s conjectured character formula for representations of complex semi-simple Lie algebras.

The second is the construction (building on earlier work with Ben Elias and Xuhua He) of counterexamples to the expected bounds in Lusztig’s conjectured character formula for rational representations of algebraic groups in positive characteristics that grow exponentially with the rank of the group.

The awards will be presented at the 2016 Clay Research Conference at Oxford on Wednesday, 28 September.

## Hausdorff Cinema at MPIM: The Discrete Charm of Geometry

A team of mathematicians is working together on a big project. Excitement of discovery, hope and disappointment, competition and recognition are shown from an infinitely close distance. Scientists united by the idea of discretization, which, in short, means: constructing continuous objects from basic building blocks. Akin to the scientists’ search for the right discretization of continuum, this film itself is composed of fragments – individual characters of different ages, temperaments and scientific approaches – which form a single continuous melody.

## MPIM at play: Informal concert on Thursday, January 21

This Thursday, January 21st at 19:00h, members of the larger MPIM community will give us the honor of an informal musical concert. First, Carmen Rovi (Piano), Matthias Kreck (Cello), and Yael Fregier (Baritone) will play and sing classical pieces by Mozart, Schubert, Schumann, and Wagner. This is followed by a short break and some traditional folk music performed by the MPIM folk group with Tim Ballance (fiddle), Kristian Hodén (button accordeon), Pavel Mnev (flutes), Davide Spriano (electric bass), and Alessandro Valentino (acoustic guitar). Everybody from the math community in Bonn and their families are welcome.

## Conference on the Cohomology of Arithmetic Groups on the occasion of Joachim Schwermer's 66th birthday

#### Speakers

F. Calegari

L. Clozel

N. Grbac

K.-W. Lan

A. Lubotzky

J. Mahnkopf

C. Moeglin

W. Müller

A. Raghuram

A. Reid

N. Schappacher

A. Scholl

P. Scholze

T. Venkataramana

## Geordie Williamson to Receive 2016 AMS Chevalley Prize

**Geordie Williamson**, advanced researcher at the Max Planck Institute for Mathematics in Bonn, will receive the Chevalley Prize in Lie Theory of the American Mathematical Society "for his work on the representation theory of Lie algebras and algebraic groups which includes proofs and reproofs of some longstanding conjectures as well as spectacular counterexamples to the expected bounds in others." Williamson is the inaugural recipient of the Chevalley Prize, which was established through a donation by MIT mathematician George Lusztig.