Here's a snippet from the current series of 'Me and My Maths', excellently edited by Evan. Tommy is a visiting student. 

Covering integers by x2 + dy2
Green, B Soundararajan, K Journal of the Institute of Mathematics of Jussieu volume 24 issue 3 847-889 (18 Mar 2025)
Forty years of the Ellis–Baldwin test
Secrest, N von Hausegger, S Rameez, M Mohayaee, R Sarkar, S Nature Reviews Physics (06 Jan 2025)
On a conjecture of Marton
Gowers, T Green, B Manners, F Tao, T Annals of Mathematics volume 201 issue 2 515-549 (12 Mar 2025)
Tue, 27 May 2025
14:00
L6

TBC

Jon Pridham
(Edinburgh University)
Abstract

to follow

Green Templeton's annual Ceilidh is in our building again this year on the evening of Friday 24th January at 9.30 pm and we have been reserved 30 free tickets which you can access using the following link and access code.

Burns Night Tickets[ Code: GTCMATHS25

Please use your maths email addresses when booking tickets.

Thu, 23 Jan 2025
16:00
Lecture Room 4

Continuity of heights and complete intersections in toric varieties

Michal Szachniewicz
((University of Oxford))
Abstract

I will describe the contents of a joint project with Pablo Destic and Nuno Hultberg. In the paper we confirm a conjecture of Roberto Gualdi regarding a formula for the average height of the intersection of twisted (by roots of unity) hyperplanes in a toric variety. I will introduce the 'GVF analytification' of a variety, which is defined similarly as the Berkovich analytification, but with norms replaced by heights. Moreover, I will discuss some motivations coming from (continuous) model theory and Arakelov geometry.

Thu, 23 Jan 2025

11:00 - 12:00
L5

A new axiom for Q_p^ab and non-standard methods for perfectoid fields

Leo Gitin
(University of Oxford)
Abstract

The class of henselian valued fields with non-discrete value group is not well-understood. In 2018, Koenigsmann conjectured that a list of seven natural axioms describes a complete axiomatisation of Q_p^ab, the maximal extension of the p-adic numbers Q_p with abelian Galois group, which is an example of such a valued field. Informed by the recent work of Jahnke-Kartas on the model theory of perfectoid fields, we formulate an eighth axiom (the discriminant property) that is not a consequence of the other seven. Revisiting work by Koenigsmann (the Galois characterisation of Q_p) and Jahnke-Kartas, we give a uniform treatment of their underlying method. In particular, we highlight how this method yields short, non-standard model-theoretic proofs of known results (e.g. finite extensions of perfectoid fields are perfectoid).

Mon, 10 Mar 2025
15:30
L5

Uniform spectral gaps above the tempered gap

Vikram Giri
(ETH Zurich)
Abstract
We will explore the possibility of getting uniform spectral gaps for some invariant differential operators on hyperbolic manifolds. We will see a construction of a sequence of hyperbolic 3-manifolds with a uniform spectral gap for the 1-form Laplacian acting on coclosed forms and conclude with an application of having such gaps to torsion homology growth. Based on joint works with A. Abdurrahman, A. Adve, B. Lowe, and J. Zung.
Mon, 03 Mar 2025
15:30
L5

The Gauss-Manin connection in noncommutative geometry

Ezra Getzler
(Northwestern University and Uppsala University)
Abstract

The noncommutative Gauss-Manin connection is a flat connection on the periodic cyclic homology of a family of dg algebras (or more generally, A-infinity categories), introduced by the speaker in 1991.

The problem now arises of lifting this connection to the complex of periodic cyclic chains. Such a lift was provided in 2007 by Tsygan, though without an explicit formula. In this talk, I will explain how this problem is simplified by considering a new A-infinity structure on the de Rham complex of a derived scheme, which we call the Fedosov product; in joint work with Jones in 1990, the speaker showed that this product plays a role in a multiplicative version of the Hochschild-Kostant-Rosenberg theorem, and the point of the present talk is that it seems to be the correct product on the de Rham complex for derived geometry.

Let be an open subset of a derived affine space parametrizing a family of -algebras . We will construct a chain level lift of the Gauss-Manin connection that satisfies a new equation that we call the Fedosov equation: .

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