Royal Holloway - Pure Mathematics
Seminar

The PM-seminar takes place on Wednesday
at 2pm in Arts-LT1 (unless stated otherwise).

Here
is a campus plan.

**Summer term 2019:**

May 1 **Indira
Chattereji** (Nice)

**"Property
(T) and actions on Lp spaces"**

Abstract:
Discrete countable groups with property (T) are exactly those that do not admit
any proper affine isometric action on a Hilbert space. I will recall basic
facts about property (T) and discuss possible variations, involving actions on Lp spaces.

May 8 **Jonathan Gross** (Columbia)

**"Partial-Dual
Genus Polynomials: Ribbons, Permutations, and Flags"**

Abstract: We are concerned with a reconciliation of some alternative
representations of embedded graphs and of the corresponding representations of
partial duals. We define the partial-dual genus polynomial of an embedded
graph G to be the generating function for the numbers of partial duals of G
according to the genus of the embedding surfaces. We demonstrate that
using the permutation representation (monodromy) by a bi-rotation system and an involution
facilitates face-tracing and thereby simpifies the
automated calculation of partial-dual genus polynomials.

May 15 **Ellen
Henke** (Aberdeen)

**"****Introduction to fusion
systems****"**

Abstract: In the study of saturated fusion
systems, previously independent developments in local finite group theory, in
modular representation theory and in homotopy theory
come together. I will give an introduction to the theory and mention some of my
own results along the way. In particular, I will talk about a programme of
Michael Aschbacher to revisit the classification of
finite simple groups using fusion systems.

May 22 **Imre**** Leader**
(Cambridge)

**"The Graham-Pollak Problem for Hypergraphs"**

Abstract: How many complete bipartite graphs do
we need to decompose the complete graph on $n$ vertices? It is easy to achieve
this with $n-1$ complete bipartite graphs, and the Graham-Pollak
Theorem states that this is the minimum. What happens for hypergraphs?
For example, how many complete tripartite 3-graphs do we need
to decompose the complete 3-graph on $n$ vertices? We will report on
recent progress on this question. Joint work with Luka Milicevic
and Ta Sheng Tan.

May 29

June 19 **Geetha**** Venkataraman**
(Ambedkar University Delhi): at 2pm in Bourne LT2.

**"Enumeration
of Groups in Varieties of A-groups"**

Abstract:

**Previous Pure
Mathematics Seminars **