Thu, 16 Nov 2017
16:00
C5

The Einstein Equation on Manifolds with Large Symmetry Groups

Timothy Buttsworth
(The University of Queensland)
Abstract

In this talk I will discuss the problem of finding Einstein metrics in the homogeneous and cohomogeneity one setting. 
In particular, I will describe a recent result concerning existence of solutions to the Dirichlet problem for cohomogeneity one Einstein metrics.

Fri, 01 Dec 2017

16:00 - 17:00
L1

New developments in the synthetic theory of metric measure spaces with Ricci curvature bounded from below

Luigi Ambrosio
(Scuola Normale Superiore di Pisa)
Abstract

The theory of metric measure spaces with Ricci curvature from below is growing very quickly, both in the "Riemannian" class RCD and the general  CD one. I will review some of the most recent results, by illustrating the key identification results and technical tools (at the level of calculus in metric measure spaces) underlying these results.
 

Wed, 18 Oct 2017

16:00 - 17:00
C5

Conformal dimension

David Hume
(University of Oxford)
Abstract

I will present a gentle introduction to the theory of conformal dimension, focusing on its applications to the boundaries of hyperbolic groups, and the difficulty of classifying groups whose boundaries have conformal dimension 1.

Thu, 30 Nov 2017

12:00 - 13:00
L4

McKean–Vlasov problems with contagion effects

Sean Ledger
(University of Bristol)
Abstract

I will introduce a McKean—Vlasov problem arising from a simple mean-field model of interacting neurons. The equation is nonlinear and captures the positive feedback effect of neurons spiking. This leads to a phase transition in the regularity of the solution: if the interaction is too strong, then the system exhibits blow-up. We will cover the mathematical challenges in defining, constructing and proving uniqueness of solutions, as well as explaining the connection to PDEs, integral equations and mathematical finance.

Tue, 24 Oct 2017

14:30 - 15:00
L5

Network Block Decomposition for Revenue Management

Jaroslav Fowkes
(University of Oxford)
Abstract

In this talk we introduce a novel dynamic programming (DP) approximation that exploits the inherent network structure present in revenue management problems. In particular, our approximation provides a new lower bound on the value function for the DP, which enables conservative revenue forecasts to be made. Existing state of the art approximations of the revenue management DP neglect the network structure, apportioning the prices of each product, whereas our proposed method does not: we partition the network of products into clusters by apportioning the capacities of resources. Our proposed approach allows, in principle, for better approximations of the DP to be made than the decomposition methods currently implemented in industry and we see it as an important stepping stone towards better approximate DP methods in practice.

Tue, 24 Oct 2017

14:00 - 14:30
L5

Gaussian Processes for Demand Unconstraining

Ilan Price
(University of Oxford)
Abstract

One of the key challenges in revenue management is unconstraining demand data. Existing state of the art single-class unconstraining methods make restrictive assumptions about the form of the underlying demand and can perform poorly when applied to data which breaks these assumptions. In this talk, we propose a novel unconstraining method that uses Gaussian process (GP) regression. We develop a novel GP model by constructing and implementing a new non-stationary covariance function for the GP which enables it to learn and extrapolate the underlying demand trend. We show that this method can cope with important features of realistic demand data, including nonlinear demand trends, variations in total demand, lengthy periods of constraining, non-exponential inter-arrival times, and discontinuities/changepoints in demand data. In all such circumstances, our results indicate that GPs outperform existing single-class unconstraining methods.

The importance of a University's teaching may seem a given, but it has received additional scrutiny in the last twelve months via the Government's Teaching Excellence Framework (TEF) and more widely as part of a debate on what Universities should offer their students. Oxford has annual teaching awards, voted by its most demanding assessors, namely its students, and this year plenty of mathematicians - Faculty, Postdocs and Graduate students - featured in those awards.

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