Tue, 07 Mar 2017
14:15
L4

The rationality of blocks of quasi-simple finite groups

Niamh Farrell
(City University London)
Abstract

The Morita Frobenius number of an algebra is the number of Morita equivalence classes of its Frobenius twists. Morita Frobenius numbers were introduced by Kessar in 2004 in the context of Donovan’s Conjecture in block theory. I will present the latest results of a project in which we aim to calculate the Morita Frobenius numbers of the blocks of quasi-simple finite groups. I will also discuss the importance of a recent result of Bonnafe-Dat-Rouquier for our methods, and explain the relationship between Morita Frobenius numbers and Donovan’s Conjecture. 

Mon, 06 Mar 2017

14:15 - 15:15
L4

Moduli spaces of instanton sheaves on projective space

Marcos Jardim
(Campinas (visiting Edinburgh))
Abstract

Instanton bundles were introduced by Atiyah, Drinfeld, Hitchin and Manin in the late 1970s as the holomorphic counterparts, via twistor
theory, to anti-self-dual connections (a.k.a. instantons) on the sphere S^4. We will revise some recent results regarding some of the basic
geometrical features of their moduli spaces, and on its possible degenerations. We will describe the singular loci of instanton sheaves,
and how these lead to new irreducible components of the moduli space of stable sheaves on the projective space.

Thu, 16 Feb 2017
12:00
L5

The spreading speed of solutions of the non-local Fisher KPP equation

Sarah Penington
(University of Oxford)
Abstract


The non-local Fisher KPP equation is used to model non-local interaction and competition in a population. I will discuss recent work on solutions of this equation with a compactly supported initial condition, which strengthens results on the spreading speed obtained by Hamel and Ryzhik in 2013. The proofs are probabilistic, using a Feynman-Kac formula and some ideas from Bramson's 1983 work on the (local) Fisher KPP equation.

Thu, 09 Feb 2017
12:00
L5

Analyticity of Rotational Travelling Water Waves

Joachim Escher
(Gottfried Wilhelm Leibniz Universität Hannover)
Abstract
Of concern is the regularity of solutions to the classical water wave problem for two-dimensional Euler flows with vorticity. It is shown that the profile together with all streamlines beneath a periodic water wave travelling over a flat bed are real-analytic curves, provided that the vorticity function is merely integrable and that there are no stagnation points in the flow. It is furthermore exposed that the analyticity of streamlines can be used to characterise intrinsically symmetric water waves. 
Thu, 02 Feb 2017
12:00
L5

Macroscopic temperature profiles in non-equilibrium stationary states

Stefano Olla
(Université Paris Dauphine)
Abstract

Systems that have more than one conserved quantity (i.e. energy plus momentum, density etc.), can exhibit quite interesting temperature profiles in non-equilibrium stationary states. I will present some numerical experiment and mathematical result. I will also expose some other connected problems, always concerning thermal boundary conditions in hydrodynamic limits.
 

Thu, 26 Jan 2017
12:00
L5

Patlak-Keller-Segel equations

Jan Burczak
(University of Oxford)
Abstract

Patlak-Keller-Segel equations 
\[
\begin{aligned}
u_t - L u &= - \mathop{\text{div}\,} (u \nabla v) \\
v_t - \Delta v &= u,
\end{aligned}
\]
where L is a dissipative operator, stem from mathematical chemistry and mathematical biology.
Their variants describe, among others, behaviour of chemotactic populations, including feeding strategies of zooplankton or of certain insects. Analytically, Patlak-Keller-Segel equations reveal quite rich dynamics and a delicate global smoothness vs. blowup dichotomy. 
We will discuss smoothness/blowup results for popular variants of the equations, focusing on the critical cases, where dissipative and aggregative forces seem to be in a balance. A part of this talk is based on joint results with Rafael Granero-Belinchon (Lyon).

Thu, 23 Feb 2017
12:00
L5

A variational perspective on wrinkling patterns in thin elastic sheets

Peter Bella
(Universitaet Leipzig)
Abstract
Wrinkling of thin elastic sheets can be viewed as a way how to avoid compressive stresses. While the question of where the wrinkles appear is well-understood, understanding properties of wrinkling is not trivial. Considering a variational viewpoint, the problem amounts to minimization of an elastic energy, which can be viewed as a non-convex membrane energy singularly perturbed by a higher-order bending term. To understand the global minimizer (ground state), the first step is to identify its energy, in particular its dependence on the small physical parameter (thickness). I will discuss several problems where the optimal energy scaling law was identified.
 
Thu, 26 Jan 2017
14:00
L4

A Ringel duality formula inspired by Knörrer equivalences for 2d cyclic quotient singularities

Martin Kalck
(Edinburgh)
Abstract

We construct triangle equivalences between singularity categories of
two-dimensional cyclic quotient singularities and singularity categories of
a new class of finite dimensional local algebras, which we call Knörrer
invariant algebras. In the hypersurface case, we recover a special case of Knörrer’s equivalence for (stable) categories of matrix factorisations.
We’ll then explain how this led us to study Ringel duality for
certain (ultra strongly) quasi-hereditary algebras.
This is based on joint work with Joe Karmazyn.

Thu, 09 Mar 2017

16:00 - 17:00
L6

Euclidean lattices of infinite rank and Diophantine applications

Jean-Benoît Bost
(Paris-Sud, Orsay)
Abstract

I will discuss the definitions and the basic properties of some infinite dimensional generalizations of Euclidean lattices and of their invariants defined in terms of theta series. Then I will present some of their applications to transcendence theory and Diophantine geometry.

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