Tue, 03 Feb 2026
16:00
L6

L-functions and conformal field theory (Joint String/RMT seminar, SPECIAL TIME 4pm)

Dalmil Mazáč
(Institut de Physique Théorique of CEA-Saclay)
Abstract

Recently, a close parallel emerged between conformal field theory in general dimension and the theory of automorphic forms. I will review this connection and explain how it can be leveraged to make rigorous progress on central open problems of number theory, using methods borrowed from the conformal bootstrap. In particular, I will use the crossing equation to prove new subconvex bounds on L-functions. Based on work with Adve, Bonifacio, Kravchuk, Pal, Radcliffe, and Rogelberg: https://arxiv.org/abs/2508.20576.

Thu, 05 Mar 2026

12:00 - 13:00
C5

Macroscopic PDEs for Spiking Neurons: After Blow-up

Xu'an Dou
(Peking University)
Abstract

Neurons interact via spikes, which is a pulse-like, discontinuous mechanism. Their mean-field PDE description gives Fokker-Planck equations with novel nonlinearities. From a probability point of view, these give rise to Mckean-Vlasov equations involving hitting times. Similar mechanisms also arise in models for systemic risk in mathematical finance, and the supercooled Stefan problem. In this talk, we will first present models for spiking neurons: both microscopic particle models and macroscopic PDE models, with an emphasis on the general mathematical structure. A central question for these equations is the finite-time blow-up of the firing rate, which scientifically corresponds to the synchronization of a neuronal network. We will discuss how to continue the solution physically after the blow-up, by introducing a new timescale. The new timescale also helps us to understand the long term behavior of the equation, as it reveals a hidden contraction structure in the hyperbolic case. Finally, we will present a recently developed numerical solver based on this framework. Numerical tests show that during the synchronization the standard microscopic solver suffers from a rather demanding time step requirement, while our macro-mesoscopic solver does not.

Massada Public Seminar @Worcester College 

Itay Glazer (Technion, Israeli Institute of Technology)  -  The Mathematics of Shuffling

Mon 9 Feb 2026 5:15 - 7:00 pm, Sultan Nazrin Shah Centre, Worcester College

Book here

Thu, 15 Jan 2026
14:00
C1

Igusa stacks and the cohomology of Shimura varieties

Pol van Hoften
(Zhejiang University)
Abstract
Associated to a modular form $f$ is a two-dimensional Galois representation whose Frobenius eigenvalues can be expressed in terms of the Fourier coefficients of $f$, using a formula known as the Eichler--Shimura congruence relation. This relation was proved by Eichler--Shimura and Deligne by analyzing the mod p (bad) reduction of the modular curve of level $\Gamma_0(p)$. In this talk, I will discuss joint work with Patrick Daniels, Dongryul Kim and Mingjia Zhang, where we give a new proof of this congruence relation that happens "entirely on the rigid generic fibre". More precisely, we prove a compatibility result between the cohomology of Shimura varieties of abelian type and the Fargues--Scholze semisimple local Langlands correspondence, generalizing the Eichler--Shimura relation of Blasius--Rogawski. Our proof makes crucial use of the Igusa stacks that we construct, generalizing earlier work of Zhang, ourselves, and Kim.
 
Quantization of the Willmore energy in Riemannian manifolds
Michelat, A Mondino, A Advances in Mathematics
Thu, 12 Feb 2026

12:00 - 12:30
Lecture Room 4, Mathematical Institute

Sharp error bounds for approximate eigenvalues and singular values from subspace methods

Irina-Beatrice Haas
((Mathematical Institute University of Oxford))
Abstract

Irina-Beatrice Haas will talk about; 'Sharp error bounds for approximate eigenvalues and singular values from subspace methods'
 

Subspace methods are commonly used for finding approximate eigenvalues and singular values of large-scale matrices. Once a subspace is found, the Rayleigh-Ritz method (for symmetric eigenvalue problems) and Petrov-Galerkin projection (for singular values) are the de facto method for extraction of eigenvalues and singular values. In this work we derive error bounds for approximate eigenvalues obtained via the Rayleigh-Ritz process. Our bounds are quadratic in the residual corresponding to each Ritz value while also being robust to clustered Ritz values, which is a key improvement over existing results. We apply these bounds to several methods for computing eigenvalues and singular values, including Krylov methods and randomized algorithms.

 

 

 

Thu, 29 Jan 2026

12:00 - 12:30
Lecture Room 4, Mathematical Institute

The latent variable proximal point algorithm for variational problems with inequality constraints

Dr John Papadopoulos
((Mathematical Institute University of Oxford))
Abstract
Dr John Papadopoulos is going to talk about: 'The latent variable proximal point algorithm for variational problems with inequality constraints'
 
The latent variable proximal point (LVPP) algorithm is a framework for solving infinite-dimensional variational problems with pointwise inequality constraints. The algorithm is a saddle point reformulation of the Bregman proximal point algorithm. Although equivalent at the continuous level, the saddle point formulation is significantly more robust after discretization.
 
LVPP yields simple-to-implement numerical methods with robust convergence and observed mesh-independence for obstacle problems, contact, fracture, plasticity, and others besides; in many cases, for the first time. The framework also extends to more complex constraints, providing means to enforce convexity in the Monge--Ampère equation and handling quasi-variational inequalities, where the underlying constraint depends implicitly on the unknown solution. Moreover the algorithm is largely discretization agnostic allowing one to discretize with very-high-order $hp$-finite element methods in an efficient manner. In this talk, we will describe the LVPP algorithm in a general form and apply it to a number problems from across mathematics.


 

Further Information
Thu, 22 Jan 2026

12:00 - 12:30
Lecture Room 4, Mathematical Institute

General Matrix Optimization

Casey Garner
((Mathematical Institute University of Oxford))
Abstract

Casey Garner will talk about; 'General Matrix Optimization'

Since our early days in mathematics, we have been aware of two important characteristics of a matrix, namely, its coordinates and its spectrum. We have also witnessed the growth of matrix optimization models from matrix completion to semidefinite programming; however, only recently has the question of solving matrix optimization problems with general spectral and coordinate constraints been studied. In this talk, we shall discuss recent work done to study these general matrix optimization models and how they relate to topics such as Riemannian optimization, approximation theory, and more.

Search for dark matter in association with a Higgs boson at the LHC: A model independent study
Baradia, S Bhattacharyya, S Datta, A Dutta, S Roy Chowdhury, S Sarkar, S Nuclear Physics B volume 1022 (01 Jan 2026)
Mon, 09 Mar 2026
14:15
L4

Gromov-Witten theory of K3 surfaces

Rahul Pandharipande
(ETH Zurich)
Abstract
The missing piece of a formally complete solution of the
reduced Gromov-Witten of K3 surfaces is the proof of a
multiple cover formula conjectured with Oberdieck  more than a
decade ago. After introducing the problem, I will explain 
work in progress with Oberdieck where the full formula is
deduced from (at the moment) conjectural GW/PT properties
for families. The geometry is related also to the study of tautological classes on the moduli of K3 surfaces.  
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