Fri, 24 Oct 2025
13:00
L6

Generalized Persistent Laplacians and Their Spectral Properties

Arne Wolf
(Imperial College)
Abstract
Laplacian operators are classical objects that are fundamental in both pure and applied mathematics and are becoming increasingly prominent in modern computational and data science fields such as applied and computational topology and application areas such as machine learning and network science. In our recent paper, we introduce a unifying operator-theoretic framework of generalized Laplacians as invariants that encompasses and extends all existing constructions, from discrete combinatorial settings to de Rham complexes of smooth manifolds. Within this framework, we introduce and study a generalized notion of persistent Laplacians. While the classical persistent Laplacian fails to satisfy the desirable properties of monotonicity and stability - both crucial for robustness and interpretability - our framework allows to isolate and analyze these properties systematically.  We demonstrate that their component maps, the up- and down-persistent Laplacians, satisfy these properties individually. Moreover, we provide a condition for full monotonicity and show that the spectra of these separate components fully determine the spectra of the full Laplacians, making them not only preferable but sufficient for analysis. We study these questions comprehensively, in both the finite and infinite dimensional settings. Our work expands and strengthens the theoretical foundation of generalized Laplacian-based methods in pure, applied, and computational mathematics.


 

Tue, 04 Nov 2025
16:00

TBA

Sean Hartnoll
Further Information

(joint with number theory)

Persistent homology classifies parameter dependence of patterns in Turing systems
spector, R Harrington, H Gaffney, E Bulletin of Mathematical Biology
Tue, 21 Oct 2025

16:00 - 17:00
L6

Randomness in the Spectrum of the Laplacian: From Flat Tori to Hyperbolic Surfaces of High Genus

Prof. Jens Marklof
(University of Bristol )
Abstract

I will report on recent progress on influential conjectures from the 1970s and 1980s (Berry-Tabor, Bohigas-Giannoni-Schmit), which suggest that the spectral statistics of the Laplace-Beltrami operator on a given compact Riemannian manifold should be described either by a Poisson point process or by a random matrix ensemble, depending on whether the  geodesic flow is integrable or “chaotic”. This talk will straddle aspects of analysis, geometry, probability, number theory and ergodic theory, and should be accessible to a broad audience. The two most recent results presented in this lecture were obtained in collaboration with Laura Monk and with Wooyeon Kim and Matthew Welsh. 

On the generalized Ramanujan and Arthur conjectures over function fields
Ciubotaru, D Harris, M Annals of Mathematics
Thu, 20 Nov 2025

12:00 - 12:30
Lecture Room 4

TBA

Ganghui Zhang
(Mathematical Institute (University of Oxford))
Abstract

TBA

Thu, 27 Nov 2025

12:00 - 13:00
L3

OCIAM TBC

Karel Devriendt
((Mathematical Institute University of Oxford))
Thu, 06 Nov 2025
17:00
L3

TBA

Vincenzo Mantova
(University of Leeds)
Abstract
TBA
Thu, 04 Dec 2025
17:00
L3

Sharply k-homogeneous actions on Fraïssé structures

Robert Sullivan
(Charles University, Prague)
Abstract
Given an action of a group G on a relational Fraïssé structure M, we call this action *sharply k-homogeneous* if, for each isomorphism f : A -> B of substructures of M of size k, there is exactly one element of G whose action extends f. This generalises the well-known notion of a sharply k-transitive action on a set, and was previously investigated by Cameron, Macpherson and Cherlin. I will discuss recent results with J. de la Nuez González which show that a wide variety of Fraïssé structures admit sharply k-homogeneous actions for k ≤ 3 by finitely generated virtually free groups. Our results also specialise to the case of sets, giving the first examples of finitely presented non-split infinite groups with sharply 2-transitive/sharply 3-transitive actions.
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