Wed, 03 Dec 2025
11:00
L4

What future for mathematics?

Ivan Nourdin
(University of Luxembourg)
Abstract

In this talk, we will explore the emerging role of generative AI in mathematical research. Building on insights from the “Malliavin–Stein experiment”, carried out in collaboration with Charles-Philippe Diez and Luis Da Maia, we will discuss our experience and reflect on how AI might influence the way mathematics is conceived, proven, and created.

Tue, 04 Nov 2025
12:00
L4

Lean tutorial (part 1)

Remy Degenne
(INRIA LILLE)
Abstract
This tutorial will be a hands-on introduction to proving theorems in Lean, using its mathematical library Mathlib. It will not assume any previous knowledge about formal theorem provers. We will discover the Lean language, learn how to read a statement and a proof, and learn the essential "tactics" one can use to prove theorems in Lean.
Participants should come with a computer, and it would be best if they could install Lean before the tutorial by following the instructions at https://lean-lang.org/install/ . The installation should be easy and takes only a few minutes.
Tue, 25 Nov 2025

14:00 - 15:00
L4

Poset Saturation - From the Diamond to the General Case

Maria-Romina Ivan
(University of Cambridge, Stanford University)
Abstract

Given a finite poset $P$ we ask how small a family of subsets of $[n]$ can be such that it does not contain an induced copy of the poset, but adding any other subset creates such a copy. This number is called the saturation number of $P$, denoted by $\operatorname{sat}^*(n,P)$. Despite the apparent similarity to the saturation for graphs, this notion is vastly different. For example, it has been shown that the saturation numbers exhibit a dichotomy: for any poset, the saturation number is either bounded, or at least $2 n^{1/2}$. In fact, it is believed that the saturation number is always bounded or exactly linear. In this talk we will be discussing the most recent advances in this field, with the focus on the diamond poset, whose saturation number was unknown until recently.

Joint with Sean Jaffe.

Wed, 22 Oct 2025
11:00
L4

Two partition-function approaches to non-symmetric random tensor eigenvalues

Giacomo La Scala
(Oxford University)
Abstract
At large N, random matrices with Gaussian distributed entries follow the Wigner semicircular law for the distribution of their eigenvalues. Random tensors are of interest in contexts of d > 2 dimensional quantum theories but do not enjoy simple generalisations of eigenvalues. Work has recently been done by Gurau to extend Wigner’s law to totally symmetric random tensors, with an approach inspired by the partition function of a Gaussian p-spin model. Starting from Gurau’s approach, I will motivate and introduce two new attempts to define and study eigenvalues of non-symmetric random tensors through partition functions, at finite and large N. One approach, based on a definition of a characteristic function, will be related to Gurau’s distribution. The other, based on a permuted definition of eigenvalues, will hint at a universality with differently-computed distributions for symmetric and complex random tensors.
Thu, 04 Dec 2025
14:00
L4

On the Categorical ’t Hooft Expansion

Niklas Garner
Abstract

The ’t Hooft expansion is a powerful organizational framework for understanding QFTs as perturbations away from the large N limit and has deep connections to string theory and holography. In this talk, I will discuss categorical aspects of the ’t Hooft expansion, i.e. what one learns about topological defects from the ’t Hooft expansion and, correspondingly, topological strings and twisted holography. This talk is based off the paper arXiv:2411.00760 from last year as well as the more recent review paper arXiv:2511.19776.

Thu, 27 Nov 2025
14:00
L4

Super-(conformal) monodromy defects

Andrea Conti (University of Oviedo)
Abstract
Recently, there has been an increasing interest in the study of defects in quantum field theories, with holography providing a powerful framework to explore various aspects of these super-(conformal) gauge theories.
In this talk, I will discuss supergravity solutions that are dual to codimension-2 superconformal monodromy defects. These solutions are obtained using gauged supergravities in D=4,5,6 and 7 dimensions. I will present a prescription to compute the defect entanglement entropy, outlining the renormalization procedure needed to regularise its divergencies, which I will discuss in detail. In some cases, we are also able to express this quantity in terms of the free energy/Weyl anomaly  and the conformal weight of the defect. In addition, we examine whether the defect entanglement entropy obeys a monotonicity theorem under RG flows.
If time allows, I will also discuss some new results for non-conformal monodromy defects.
Thu, 13 Nov 2025
14:00
L4

Thermal correlators, QNMs and signatures of bulk black holes

Robin Karlsson
Abstract

I will discuss some of my work on thermal correlators in AdS/CFT. In particular, given a thermal correlator, how are the characteristic properties of bulk black holes encoded in such correlators? This includes exploring the spectrum of QNMs, the so-called thermal product formula, the photon ring, and geodesics bouncing off the black hole singularity. I will discuss how the latter might change when finite string effects are considered.

Thu, 06 Nov 2025
14:00
L4

Journal Club Cancelled

Abstract

There will be no journal club this week to avoid conflicting with FPUK.

Thu, 30 Oct 2025
14:00
L4

Sine dilaton gravity: wormholes, finite matrices and q-holography

Jacopo Papalini (Ghent University)
Abstract

I will discuss a two-dimensional dilaton gravity theory with a sine potential. At the disk level, this theory admits a microscopic holographic realization as the double-scaled SYK model. Remarkably, in the open channel canonical quantization of the theory, the momentum conjugate to the length of two-sided Cauchy slices becomes periodic. As a result, the ERB length in sine dilaton gravity is discretized upon gauging this symmetry. For closed Cauchy slices, a similar discretization occurs in the physical Hilbert space, corresponding to a discrete spectrum for the length of the necks of trumpet geometries. By appropriately gluing two such trumpets together, one can then construct a wormhole geometry in sine dilaton gravity, whose amplitude matches the spectral correlation functions of a one-cut matrix integral. This correspondence suggests that the theory provides a path integral formulation of q-deformed JT gravity, where the matrix size is large but finite. Finally, I will describe how this theory of gravity can be regarded as a realization of q-deformed holography and propose a possible implementation of this framework to study the near-horizon dynamics of near-extremal de Sitter black holes.

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