Royal Holloway - Pure Mathematics
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.