Mon, 27 Feb 2023
15:30
L4

SL(2,C)-character varieties of knots and maps of degree 1

Raphael Zentner
(Durham University)
Abstract

We ask to what extend the SL(2,C)-character variety of the
fundamental group of the complement of a knot in S^3 determines the
knot. Our methods use results from group theory, classical 3-manifold
topology, but also geometric input in two ways: the geometrisation
theorem for 3-manifolds, and instanton gauge theory. In particular this
is connected to SU(2)-character varieties of two-component links, a
topic where much less is known than in the case of knots. This is joint
work with Michel Boileau, Teruaki Kitano, and Steven Sivek.

Unsung heros of science
Ghilencea, D Sarkar, S Proceedings of Science volume 406 (23 Nov 2022)
Indirect neural-based finite-time integral sliding mode control for trajectory tracking guidance of Mars entry vehicle
Yao, Q Jahanshahi, H Moroz, I Bekiros, S Alassafi, M Advances in Space Research volume 71 issue 9 3723-3733 (06 Dec 2022)
Fri, 10 Mar 2023

12:00 - 13:00
N3.12

Introduction to Relative Algebraic Geometry

Rhiannon Savage
(University of Oxford)
Abstract

In the theory of relative algebraic geometry, our affines are objects in the opposite category of commutative monoids in a symmetric monoidal category $\mathcal{C}$. This categorical approach simplifies many constructions and allows us to compare different geometries. Toën and Vezzosi's theory of homotopical algebraic geometry considers the case when $\mathcal{C}$ has a model structure and is endowed with a compatible symmetric monoidal structure. Derived algebraic geometry is recovered when we take $\mathcal{C}=\textbf{sMod}_k$, the category of simplicial modules over a simplicial commutative ring $k$.

In Kremnizer et al.'s version of derived analytic geometry, we consider geometry relative to the category $\textbf{sMod}_k$ where $k$ is now a simplicial commutative complete bornological ring. In this talk we discuss, from an algebraist's perspective, the main ideas behind the theory of relative algebraic geometry and discuss briefly how it provides us with a convenient framework to consider derived analytic geometry. 

Fri, 03 Mar 2023

12:00 - 13:00
N3.12

Automorphisms of Quantum Toroidal Algebras and an Action of The Extended Double Affine Braid Group

Duncan Laurie
(University of Oxford)
Abstract

Quantum toroidal algebras $U_{q}(\mathfrak{g}_{\mathrm{tor}})$ are certain Drinfeld quantum affinizations of quantum groups associated to affine Lie algebras, and can therefore be thought of as `double affine quantum groups'.

In particular, they contain (and are generated by) a horizontal and vertical copy of the affine quantum group. 

Utilising an extended double affine braid group action, Miki obtained in type $A$ an automorphism of $U_{q}(\mathfrak{g}_{\mathrm{tor}})$ which exchanges these subalgebras. This has since played a crucial role in the investigation of its structure and representation theory.

In this talk I shall present my recent work -- which extends the braid group action to all types and generalises Miki's automorphism to the ADE case -- as well as potential directions for future work in this area.

Fri, 24 Feb 2023

12:00 - 13:00
N3.12

Flops and Cluster Categories

Charlotte Llewellyn
(University of Glasgow)
Abstract

The crepant resolutions of a singular threefold are related by a finite sequence of birational maps called flops. In the simplest cases, this network of flops is governed by simple combinatorics. I will begin the talk with an overview of flops and crepant resolutions. I will then move on to explain how their underlying combinatorial structure can be abstracted to define the notion of a cluster category.

Fri, 10 Feb 2023

12:00 - 13:00
N3.12

Localisation of locally analytic representations (work in progress).

Arun Soor
(University of Oxford)
Abstract

Let $G$ be a $p$-adic Lie group. From the perspective of $p$-adic manifolds, possibly the most natural $p$-adic representations of $G$ to consider are the locally analytic ones.  Motivated by work of Pan, when $G$ acts on a rigid analytic variety $X$ (e.g., the flag variety), we would like to geometrise locally analytic $G$-representations, via a covariant localisation theory which should intertwine Schneider-Teitelbaum's duality with the $p$-adic Beilinson-Bernstein localisation. I will report some partial progress in the simplified situation when we replace $G$ by its germ at $1$. The main ingredient is an infinite jet bundle $\mathcal{J}^\omega_X$ which is dual to $\widehat{\mathcal{D}}_X$. Our "co"localisation functor is given by a coinduction to $\mathcal{J}^\omega_X$. Work in progress.

Fri, 27 Jan 2023

12:00 - 13:00
N3.12

The Pro-Étale Topology for Representation Theorists

Jonas Antor
(University of Oxford)
Abstract

Perverse sheaves are an indispensable tool in geometric representation theory that can be used to construct representations and compute composition multiplicities. These ‘sheaves’ live in a certain $\ell$-adic derived category. In this talk we will discuss a beautiful construction of this category based on the pro-étale topology and explore some applications in representation theory.

Estimating the probability that a given vector is in the convex hull of a random sample
Hayakawa, S Lyons, T Oberhauser, H Probability Theory and Related Fields volume 185 issue 3-4 705-746 (07 Jan 2023)
Mon, 20 Feb 2023
15:45

Factorization homology of braided tensor categories

Adrien Brochier
(Paris)
Abstract

Factorization homology is an arguably abstract formalism which produces
well-behaved topological invariants out of certain "higher algebraic"
structures. In this talk, I'll explain how this formalism can be made
fairly concrete in the case where this input algebraic structure is a
braided tensor category. If the category at hand is semi-simple, this in
fact essentially recovers skein categories and skein algebras. I'll
present various applications of this formalism to quantum topology and
representation theory.
 

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