# Weekly bulletin

## Week starting Monday 25 September 2017

### Tuesday 26 September - Algebra and Topology Seminar

Start time: 3.30pm
Location: John Dedman Building 27, Room G35
Presenter(s): Anthony Henderson (U. of Sydney)
Abstract:

Let $G$ be a simply connected semisimple algebraic group over $\mathbb{C}$. For reasons related to our work on nilpotent orbits, Pramod Achar and I were led to study a certain involution of an open subset of the affine Grassmannian of $G$. In this talk I will discuss a moduli-space interpretation of this involution: it corresponds to the action of the nontrivial Weyl group element of $\mathrm{SL}(2)$ on the framed moduli space of $\mathbb{G}_m$-equivariant principal $G$-bundles on $\mathbb{P}^2$. As a result, the fixed-point set of the involution can be partitioned into strata indexed by conjugacy classes of homomorphisms $N\to G$ where $N$ is the normalizer of $\mathbb{G}_m$ in $\mathrm{SL}(2)$.

### Friday 29 September - Quantum mathematics meeting

Start time: 3.30pm
Location: John Dedman Building 27, Room JD1177 (meeting room)
Presenter(s): Scott Morrison (MSI)
Abstract:

I'll define algebras in higher categories, and explain how to interpret recent work in physics on 'tensor networks' in this framework.

Updated:  25 September 2017/Responsible Officer:  Director/Page Contact:  School Manager