Fri, 01 Mar 2024

12:00 - 13:00
Quillen Room

Algebra is Hard, Combinatorics is Simple(r)

Zain Kapadia
(Queen Mary University London)
Abstract

Questions in algebra, while deep and interesting, can be incredibly difficult. Thankfully, when studying the representation theory of the symmetric groups, one can often take algebraic properties and results and write them in the language of combinatorics; where one has a wide variety of tools and techniques to use. In this talk, we will look at the specific example of the submodule structure of 2-part Specht modules in characteristic 2, and answer which hook Specht modules are uniserial in characteristic 2. We will not need to assume the Riemann hypothesis for this talk.

Mon, 15 Jan 2024

13:00 - 14:00
N3.12

Mathematrix: Interview Discussion

Abstract

Join us for a discussion about preparing for PhD and PostDoc Interviews. We will be talking to Melanie Rupflin and Mura Yakerson.

Mon, 26 Feb 2024
14:15
L4

Hessian geometry of $G_2$-moduli spaces

Thibault Langlais
(Oxford)
Abstract

The moduli space of torsion-free $G_2$-structures on a compact $7$-manifold $M$ is a smooth manifold, locally diffeomorphic to an open subset of $H^3(M)$. It is endowed with a natural metric which arises as the Hessian of a potential, the properties of which are still poorly understood. In this talk, we will review what is known of the geometry of $G_2$-moduli spaces and present new formulae for the fourth derivative of the potential and the curvatures of the associated metric. We explain some interesting consequences for the simplest examples of $G_2$-manifolds, when the universal cover of $M$ is $\mathbb{R}^7$ or $\mathbb{R}^3 \times K3$. If time permits, we also make some comments on the general case.

Mon, 29 Jan 2024
14:15
L4

Floer cohomology for symplectic ${\mathbb C}^*$-manifolds

Alexander Ritter
(Oxford)
Abstract

In this joint work with Filip Zivanovic, we construct symplectic cohomology for a class of symplectic manifolds that admit ${\mathbb C}^*$-actions and which project equivariantly and properly to a convex symplectic manifold. The motivation for studying these is a large class of examples known as Conical Symplectic Resolutions, which includes quiver varieties, resolutions of Slodowy varieties, and hypertoric varieties. These spaces are highly non-exact at infinity, so along the way we develop foundational results to be able to apply Floer theory. Motivated by joint work with Mark McLean on the Cohomological McKay Correspondence, our goal is to describe the ordinary cohomology of the resolution in terms of a Morse-Bott spectral sequence for positive symplectic cohomology. These spectral sequences turn out to be quite computable in many examples. We obtain a filtration on ordinary cohomology by cup-product ideals, and interestingly the filtration can be dependent on the choice of circle action.

Heterotic twistor-string theory
Mason, L Skinner, D (17 Aug 2007)
Gravity, Twistors and the MHV Formalism
Mason, L Skinner, D (28 Aug 2008)
Dual Superconformal Invariance, Momentum Twistors and Grassmannians
Mason, L Skinner, D (01 Sep 2009)
Twistor-Strings, Grassmannians and Leading Singularities
Bullimore, M Mason, L Skinner, D (03 Dec 2009)
Amplitudes at Weak Coupling as Polytopes in AdS_5
Mason, L Skinner, D (20 Apr 2010)
MHV Diagrams in Momentum Twistor Space
Bullimore, M Mason, L Skinner, D (09 Sep 2010)
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