Mon, 06 Mar 2023
14:15
L4

Phase transitions with Allen-Cahn mean curvature bounded in $L^p$.

Shengwen Wang
(Queen Mary University)
Abstract

We consider the varifolds associated to phase transitions whose first variation of Allen-Cahn energy is $L^p$ integrable with respect to the energy measure. We can see that the Dirichlet and potential part of the energy are almost equidistributed. After passing to the phase field limit, one can obtain an integer rectifiable varifold with bounded $L^p$ mean curvature. This is joint work with Huy Nguyen.

Mon, 27 Feb 2023
14:15
L4

Equivariant Fukaya categories at singular values

Yankı Lekili
((Imperial College, London))
Abstract

It is well understood by works of Fukaya and Teleman that the Fukaya category of a symplectic reduction at a regular value of the moment map can be computed before taking the quotient as an equivariant Fukaya category. Informed by mirror calculations,  we will give a new geometric interpretation of the equivariant Fukaya category corresponding to a singular value of the moment map where the equivariance is traded with wrapping.

Joint work in progress with Ed Segal.

Mon, 13 Feb 2023
14:15
L4

Some glueing constructions in Lagrangian mean curvature flow

Wei-Bo Su
(University of Warwick)
Abstract

Glueing construction has been used extensively to construct solutions to nonlinear geometric PDEs. In this talk, I will focus on the glueing construction of solutions to Lagrangian mean curvature flow. Specifically, I will explain the construction of Lagrangian translating solitons by glueing a small special Lagrangian 'Lawlor neck' into the intersection point of suitably rotated Lagrangian Grim Reaper cylinders. I will also discuss an ongoing joint project with Chung-Jun Tsai and Albert Wood, where we investigate the construction of solutions to Lagrangian mean curvature flow with infinite time singularities.

Mon, 30 Jan 2023
14:15
L4

Mirror symmetry and big algebras

Tamas Hausel
(IST Austria)
Abstract

First we recall the mirror symmetry identification of the coordinate ring of certain very stable upward flows in the Hitchin system and the Kirillov algebra for the minuscule representation of the Langlands dual group via the equivariant cohomology of the cominuscule flag variety (e.g. complex Grassmannian). In turn we discuss a conjectural extension of this picture to non-very stable upward flows in terms of a big commutative subalgebra of the Kirillov algebra, which also ringifies the equivariant intersection cohomology of the corresponding affine Schubert variety.

Mon, 23 Jan 2023
14:15
L4

Compactified Universal Jacobians over $\overline{\mathcal{M}}_{g,n}$ via GIT

George Cooper
((Oxford University))
Abstract

Associated to any smooth projective curve C is its degree d Jacobian variety, parametrising isomorphism classes of degree d line bundles on C. Letting the curve vary as well, one is led to the universal Jacobian stack. This stack admits several compactifications over the stack of marked stable curves $\overline{\mathcal{M}}_{g,n}$, depending on the choice of a stability condition. In this talk I will introduce these compactified universal Jacobians, and explain how their moduli spaces can be constructed using Geometric Invariant Theory (GIT). This talk is based on arXiv:2210.11457.

Mon, 16 Jan 2023
14:15
L4

Trivector fields on moduli spaces

Nigel Hitchin
((Oxford University))
Abstract

The moduli space M of stable bundles on a Riemann surface possesses a natural family of holomorphic trivector fields. The talk will introduce these objects with examples and then use them to gain information about the Hochschild cohomology of M.

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In this Oxford Mathematics Christmas Public Lecture we look at a variety of delicious delights through a lens of fluid dynamics and mathematical modelling. From perfect roast potatoes to sweet sauces, mathematics gets everywhere!

Helen Wilson is Head of the Department of Mathematics at UCL. She is best known for her work on the chocolate fountain (which features in this lecture) but does do serious mathematical modelling as well.

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