Fri, 09 May 2025
16:00
L1

Fridays@4 – From research to market: lessons from an academic founder

Professor Ali El Kaafarani and Sami Walter
Abstract

Please join us for a fireside chat, hosted by OSE, between PQShield founder and visiting professor, Dr Ali El Kaafarani, and Sami Walter, associate at Oxford Sciences Enterprises (OSE). 

Dr Ali El Kaafarani is the founder and CEO of PQShield, a post-quantum cryptography (PQC) company empowering organisations, industries and nations with quantum-resistant cryptography that is modernising the vital security systems and components of the world's technology supply chain.  

In this chat, we’ll discuss Dr Ali El Kaafarani’s experience founding PQShield and lessons learned from spinning a company out from the Oxford ecosystem.

Mon, 26 May 2025

13:00 - 14:00

Mathematrix: Crafts and Chill

Abstract

It’s a busy and stressful term for a lot of us so come and take a break and do some colouring and origami with us. Venting is very much encouraged.

Algebraically hyperbolic groups
Kielak, D Logan, A Gardam, G Groups, Geometry, and Dynamics
Mon, 16 Jun 2025
16:00
C3

Counting solutions to (some) homogeneous quadratic forms in eight prime variables

Aleksandra Kowalska
(University of Oxford)
Abstract
In 2014, Lilu Zhao counted the solutions to non-degenerate, homogeneous quadratic forms in at least nine prime variables, using the circle method. However, while the suggested formula for the number of solutions is believed to hold for forms in at least five variables, his method seems to break for general forms in less than nine variables.
In 2021, Ben Green solved the problem for forms in eight prime variables (using a very different approach), satisfying a 'genericity' condition. The aim of my project was to solve some forms in eight variables not satisfying this condition.
In the talk, I will describe my findings, which allowed me to count the number of solutions to forms in eight prime variables with off-diagonal rank 3 (i.e., which have an invertible 3x3 submatrix without diagonal entries), which is a subset of non-generic forms.
Mon, 09 Jun 2025
16:00
L6

TBC

Alexandra Kowalska
(Univesity of Oxford)
Abstract

TBC

Mon, 02 Jun 2025
16:00
L6

On the largest $k$-product-free subsets of the Alternating Groups

Anubhab Ghosal
(University of Oxford)
Abstract

A subset $A$ of $A_n$ is $k$-product-free if for all $a_1,a_2,\dots,a_k\in A$, $a_1a_2\dots a_k$ $\notin A$.
We determine the largest $3$-product-free and $4$-product-free subsets of $A_n$ for sufficiently large $n$. We also obtain strong stability results and results on multiple sets with forbidden cross products. The principal technical ingredient in our approach is the theory of hypercontractivity in $S_n$. Joint work with Peter Keevash.

Mon, 26 May 2025
16:00
L6

Large values of Dirichlet polynomials with characters

Vishal Gupta
(University of Oxford)
Abstract

Dirichlet polynomials are useful in the study of the Riemann zeta function & Dirichlet L functions, serving as approximations to them via the approximate functional equation. Understanding how often they can be large gives bounds on the number of zeroes of these functions in vertical strips - known as zero density estimates - which are relevant to the distribution of primes in short intervals. Based on Guth-Maynard, we study large values of Dirichlet polynomials with characters, relevant to Dirichlet L functions. Joint work with Yung Chi Li. 

Mon, 19 May 2025
16:00
L6

On derived deformations of Galois representations (after Galatius-Venkatesh)

Samuel Moore
(University of Oxford)
Abstract


Given a mod $p$ Galois representation, one often wonders whether it arises by reducing a $p$-adic one, and whether these lifts are suitably 'well-behaved'. In this talk, we discuss how ideas from homotopy theory aid the study of Galois deformations, reviewing work of Galatius-Venkatesh.

Mon, 12 May 2025
16:00
L6

The moduli space of Bohr sets in R^n

Yaël Dillies
(Stockholm University)
Abstract

The arithmetic regularity lemma says that any dense set A in F_p^n can be cut along cosets of some small codimension subspace H <= F_p^n such that on almost all cosets of H, A is either random or structured (in a precise quantitative manner). A standard example shows that one cannot hope to improve "almost all" to "all", nor to have a good quantitative dependency between the constants involved. Adding a further combinatorial assumption on A to the arithmetic regularity lemma makes its conclusion so strong that one can essentially classify such sets A. In this talk, I will use use the analogous problem with F_p^n replaced with R^n as a way the motivate the funny title.

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