Wed, 06 Mar 2024

16:00 - 17:00
L6

Anosov Flows and Topology

Michael Schmalian
(University of Oxford)
Abstract

We will give a relaxed introduction to some of the most classical dynamical systems - Anosov flows. These flows were highly influential in the development of ideas which the audience might be more familiar with. For example, Anosov flows give rise to exponential group growth and taut foliations, both of which we will discuss. Finally, we will talk about some recent work obstructing Anosov flows and their combinatorial analogs - veering triangulations

Wed, 28 Feb 2024

16:00 - 17:00
L6

Revisiting property (T)

Ismael Morales
(University of Oxford)
Abstract

Property (T) was introduced by Kazhdan in the sixties to show that lattices in higher rank semisimple Lie groups are finitely generated. We will discuss some classical examples of groups that satisfy this property, with a particular focus on SL(3, R).

Wed, 07 Feb 2024

16:00 - 17:00
L6

Relationships between hyperbolic and classic knot invatiants

Colin McCulloch
(University of Oxford)
Abstract

For a hyperbolic knot there are two types of invariants, the hyperbolic invariants coming from the geometric structure and the classical invariants coming from the topology or combinatorics. It has been observed in many different cases that these seemingly different types of invariants are in fact related. I will give examples of these relationships and discuss in particular a link by Stoimenow between the determinant and volume.  

Wed, 31 Jan 2024

16:00 - 17:00
L6

Distinguishing free-by-(finite cyclic) groups by their finite quotients

Paweł Piwek
(University of Oxford)
Abstract
Finitely generated free-by-(finite cyclic) groups turn out to be distinguished from each other by their finite quotients - and this is thanks to being very constrained by their finite subgroups and their centralisers. This has a consequence to distinguishing in the same way the free-by-cyclic groups with centre. This is joint work with Martin Bridson.
Wed, 17 Jan 2024

16:00 - 17:00
L6

Spectra of surfaces and MCG actions on random covers

Adam Klukowski
(University of Oxford)
Abstract

The Ivanov conjecture is equivalent to the statement that every covering map of surfaces has the so-called Putman-Wieland property. I will discuss my recent work with Vlad Marković, where we prove it for asymptotically all coverings as the degree grows. I will give some overview of our main tool: spectral geometry, which is related to objects like the heat kernel of a hyperbolic surface, or Cheeger connectivity constant.

Fri, 26 Jan 2024

12:00 - 13:00
Quillen Room

Coadmissible modules over Fréchet-Stein algebras

Finn Wiersig
(University of Oxford)
Abstract

Let K be a non-archimedean field of mixed characteristic (0,p), and let L be a finite extension of
the p-adic numbers contained in K. The speaker is interested in the continuous representations of a
given L-analytic group G in locally convex (usually infinite dimensional) topological vector spaces over K.
This is, up to technicalities, equivalent to studying certain topological modules over the locally
analytic distribution algebra D(G,K) of G. But doing algebra with topological objects is hard!
In this talk, we present an excellent remedy, found by Schneider and Teitelbaum in the early 2000s.

Thu, 18 Jan 2024
16:00
Lecture Room 4, Mathematical Institute

Traces of random matrices over F_q, and short character sums

Ofir Gorodetsky
(University of Oxford)
Abstract
Let g be a matrix chosen uniformly at random from the GL_n(F_q), where F_q is the field with q elements. We consider two questions:
1. For fixed k and growing n, how fast does Tr(g^k) converge to the uniform distribution on F_q?
2. How large can k be taken, as a function of n, while still ensuring that Tr(g^k) converges to the uniform distribution on F_q?
We will answer these two questions (as well as various variants) optimally. The questions turn out to be strongly related to the study of particular character sums in function fields.
Based on joint works with Brad Rodgers (arXiv:1909.03666) and Valeriya Kovaleva (arXiv:2307.01344).
Thu, 29 Feb 2024
16:00
Lecture Room 4

A new approach to modularity

Andrew Wiles
(University of Oxford)
Abstract

In the 1960's Langlands proposed a generalisation of Class Field Theory. I will review this and describe a new approach using the trace formua as well as some analytic arguments reminiscent of those used in the classical case. In more concrete terms the problem is to prove general modularity theorems, and I will explain the progress I have made on this problem.

Mon, 04 Mar 2024
16:00
L2

The dispersion method and beyond: from primes to exceptional Maass forms

Alexandru Pascadi
(University of Oxford)
Abstract
The dispersion method has found an impressive number of applications in analytic number theory, from bounded gaps between primes to the greatest prime factors of quadratic polynomials. The method requires bounding certain exponential sums, using deep inputs from algebraic geometry, the spectral theory of GL2 automorphic forms, and GLn automorphic L-functions. We'll give a broad outline of this process, which combines various types of number theory; time permitting, we'll also discuss the key ideas behind some new results.
 
Mon, 26 Feb 2024
16:00
L2

The Metaplectic Representation is Faithful

Christopher Chang, Simeon Hellsten, Mario Marcos Losada, and Sergiu Novac.
(University of Oxford)
Abstract

Iwasawa algebras are completed group rings that arise in number theory, so there is interest in understanding their prime ideals. For some special Iwasawa algebras, it is conjectured that every non-zero such ideal has finite codimension and in order to show this it is enough to establish the faithfulness of the modules arising from the completion of highest weight modules. In this talk we will look at methods for doing this and apply them to the specific case of the metaplectic representation for the symplectic group.

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