Tue, 07 Mar 2017

12:00 - 13:15
L4

Approaches to quantization

Graeme Segal
Abstract

Quantization is the study of the interface between commutative and
noncommutative geometry. There are myriad approaches to it, mostly presented
as ad hoc recipes. I shall discuss the motivating ideas, and the relations
between some of the methods, especially the relation between 'deformation'
and 'geometric' quantization.

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, 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.

Tue, 28 Feb 2017

12:00 - 13:15
L4

Critical L-values from multi-loop Feynman diagrams

David Broadhurst
(Open University)
Abstract


I shall report on recent progress, in Australia and Germany, on the empirical evaluation of special values of L-functions by minors of period matrices whose elements include Feynman integrals from diagrams with up to 20 loops. Previously such relations were known only for diagrams with up to 6 loops.
 

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