Mon, 02 Jun 2025
13:00
C6

Supersymmetry is dying. Should we save it? (Debate Session, ALL ARE WELCOME)

Zhenghao Zhong
Abstract

The rise to fame of supersymmetry since the 1970s shook the world. It held much promise—from explaining naturalness, unifying fundamental forces, to being the ideal candidate for dark matter. But since the LHC (arguably even a bit before that), many of these dreams have been shattered by experiments. Today, the pursuit of supersymmetric theories by the physics community is a mere shadow of its former self.

This symposium is not to discuss whether supersymmetry is useful in the fields of physics and mathematics—it clearly is. Rather, this is a debate about whether its death is natural. We’ve had a crack at it for half a century. Is this the limit of what we can do? Are we any closer to achieving the original goals we set out? Is the death premature, accelerated by a negative campaign from SUSY critics? Or is it the other way around—has it been at death’s door for decades, kept alive only because authoritative figures cannot let go?

Twenty years ago, this wouldn’t even be a debate. Twenty years from now, there may not be any young people working on SUSY at all. This seems like the right time to talk.

Fri, 30 May 2025
14:30
L5

Minimal tension holography from a String theory in twistor space

Nathan McStay
(Cambridge )
Abstract

Explicit examples of the AdS/CFT correspondence where both bulk and boundary theories are tractable are hard to come by, but the minimal tension string on AdS_3 x S^3 x T^4  is one notable example. In this paper, we discuss how one can construct sigma models on twistor space, with a particular focus on applying these techniques to the aforementioned string theory. We derive novel incidence relations, which allow us to understand to what extent the minimal tension string encodes information about the bulk. We identify vertex operators in terms of bulk twistor variables and a map from twistor space to spacetime is presented. We also demonstrate the presence of a partially broken global supersymmetry algebra in the minimal tension string and we argue that this implies that there exists an N=2 formulation of the theory. The implications of this are studied and we demonstrate the presence of an additional constraint on physical states. This is based on work with Ron Reid-edwards https://arxiv.org/abs/2411.08836.

Fri, 30 May 2025
13:00
L5

A unified theory of topological and classical integral transforms

Vadim Lebovici

Note: we would recommend to join the meeting using the Teams client for best user experience.

Abstract

Alesker's theory of generalized valuations unifies smooth measures and constructible functions on real analytic manifolds, extending classical operations on measures. Therefore, operations on generalized valuations can be used to define integral transforms that unify both classical Radon transforms and their topological analogues based on the Euler characteristic, which have been successfully used in shape analysis. However, this unification is proven under rather restrictive assumptions in Alesker's original paper, leaving key aspects conjectural. In this talk, I will present a recent result obtained with A. Bernig that significantly closes this gap by proving that the two approaches indeed coincide on constructible functions under mild transversality assumptions. Our proof relies on a comparison between these operations and operations on characteristic cycles.

Fri, 30 May 2025
12:00
L4

Celestial symmetries of black hole horizons

Celine Zwikel
(Perimeter Institute)
Abstract

I will present a novel correspondence between the gravitational phase space at null infinity and the subleading phase space for finite-distance null hypersurfaces, such as black hole horizons. Utilizing the Newman-Penrose formalism and an off-shell Weyl transformation, this construction transfers key structures from asymptotic boundaries to null surfaces in the bulk—for instance, a notion of radiation. Imposing self-duality conditions, I will identify the celestial symmetries and construct their canonical generators for finite-distance null hypersurfaces. This framework provides new observables for black hole physics.

Fri, 30 May 2025

12:00 - 13:00
Quillen Room

Weight part of Serre's conjecture

Calle Sonne
(London School of Geometry & Number Theory)
Abstract

In the 1970s, Serre conjectured that any continuous, irreducible and odd mod p representation of the absolute Galois group G_Q is modular. Serre furthermore conjectured that there should be an explicit minimal weight "k" such that the Galois representation is modular of this weight, and that this weight only depends on the restriction of the Galois representation to the inertial subgroup I_p. This is often called the weight part of Serre's conjecture. Both the weight part, and the modularity part, of the Serre's conjecture are nowadays known to be true. In this talk, I want to explain how to rephrase the conjecture in representation theoretic terms (for k >= 2), so that the weight k is replaced by a certain (mod p) irreducible representation of GL_2(F_p), and how upon rephrasing the conjecture one can realize it as a statement about local-global compatibility with the mod p local Langlands correspondence.

Fri, 30 May 2025

11:00 - 12:00
L4

Modelling the rheology of biological tissue

Professor Suzanne Fielding
(Dept of Physics Durham University)
Abstract

The rheological (deformation and flow) properties of biological tissues  are important in processes such as embryo development, wound healing and 
tumour invasion. Indeed, processes such as these spontaneously generate  stresses within living tissue via active process at the single cell level. 
Tissues are also continually subject to external stresses and deformations  from surrounding tissues and organs. The success of numerous physiological 
functions relies on the ability of cells to withstand stress under some conditions, yet to flow collectively under others. Biological tissue is 
furthermore inherently viscoelastic, with a slow time-dependent mechanics.  Despite this rich phenomenology, the mechanisms that govern the 
transmission of stress within biological tissue, and its response to bulk deformation, remain poorly understood to date.

This talk will describe three recent research projects in modelling the rheology of biological tissue. The first predicts a strain-induced 
stiffening transition in a sheared tissue [1]. The second elucidates the interplay of external deformations applied to a tissue as a whole with 
internal active stresses that arise locally at the cellular level, and shows how this interplay leads to a host of fascinating rheological 
phenomena such as yielding, shear thinning, and continuous or discontinuous shear thickening [2]. The third concerns the formulation of 
a continuum constitutive model that captures several of these linear and nonlinear rheological phenomena [3].

[1] J. Huang, J. O. Cochran, S. M. Fielding, M. C. Marchetti and D. Bi, 
Physical Review Letters 128 (2022) 178001

[2] M. J. Hertaeg, S. M. Fielding and D. Bi, Physical Review X 14 (2024) 
011017.

[3] S. M. Fielding, J. O. Cochran, J. Huang, D. Bi, M. C. Marchetti, 
Physical Review E (Letter) 108 (2023) L042602.

Thu, 29 May 2025
17:00
L3

The hierarchy of consistency strengths for membership in a computably enumerable set

Joel David Hamkins
(University of Notre Dame)
Abstract
For a given computably enumerable set W, consider the spectrum of assertions of the form n ∈ W. If W is c.e. but not computably decidable, it is easy to see that many of these statements will be independent of PA, for otherwise we could decide W by searching for proofs of n ∉ W. In this work, we investigate the possible hierarchies of consistency strengths that arise. For example, there is a c.e. set Q for which the consistency strengths of the assertions n ∈ Q are linearly ordered like the rational line. More generally, I shall prove that every computable preorder relation on the natural numbers is realized exactly as the hierarchy of consistency strength for the membership statements n∈W of some computably enumerable set W. After this, we shall consider the c.e. preorder relations. This is joint work with Atticus Stonestrom.
Thu, 29 May 2025
16:00
L5

Sovereign debt default and climate risk

Emilio Barucci
(Politecnico di Milano)
Abstract
We explore the interplay between sovereign debt default and climate risk. Pollution  (e.g., pollution from land use, natural resource exploitation) contributes to the likelihood of natural disasters and influences economic growth rates. The country can default on its debt at any time while also deciding whether to invest in pollution abatement. The framework provides insights into the credit spreads of sovereign bonds and explains the observed relationship between bond spread and country's climate vulnerability. Through calibration for developing and low-income countries, we show that there is limited incentive for these countries to address climate risk, and the sensitivity of bond spreads to climate vulnerability is limited. Climate risk does not play a relevant role on the decision to default on sovereign debt. Financial support for climate abatement expenditures can effectively foster climate adaptation actions, instead renegotiation conditional upon pollution abatement does not produce any effect. 


 

Thu, 29 May 2025

14:00 - 15:00
Lecture Room 3

On the data-sparsity of the solution of Riccati equations with quasiseparable coefficients

Stefano Massei
(Universita di Pisa)
Abstract

Solving large-scale continuous-time algebraic Riccati equations is a significant challenge in various control theory applications. 

This work demonstrates that when the matrix coefficients of the equation are quasiseparable, the solution also exhibits numerical quasiseparability. This property enables us to develop two efficient Riccati solvers. The first solver is applicable to the general quasiseparable case, while the second is tailored to the particular case of banded coefficients. Numerical experiments confirm the effectiveness of the proposed algorithms on both synthetic examples and case studies from the control of partial differential equations and agent-based models. 

Thu, 29 May 2025

12:00 - 12:30
L4

Low-rank approximation of parameter-dependent matrices via CUR decomposition

Taejun Park
(Mathematical Institute (University of Oxford))
Abstract

Low-rank approximation of parameter-dependent matrices A(t) is an important task in the computational sciences, with applications in areas such as dynamical systems and the compression of series of images. In this talk, we introduce AdaCUR, an efficient randomised algorithm for computing low-rank approximations of parameter-dependent matrices using the CUR decomposition. The key idea of our approach is the ability to reuse column and row indices for nearby parameter values, improving efficiency. The resulting algorithm is rank-adaptive, provides error control, and has complexity that compares favourably with existing methods. This is joint work with Yuji Nakatsukasa.

Thu, 29 May 2025

12:00 - 13:00
L3

Pressure-driven fracture in elastic continuum materials

Peter Stewart
(University of Glasgow)
Further Information

Short Bio
Peter S. Stewart is a Professor of Applied Mathematics at the University of Glasgow. His research applies continuum mechanics to physiological and industrial problems. He previously held postdoctoral positions at the University of Oxford and Northwestern University, and earned his PhD from the University of Nottingham with a thesis on flows in flexible channels and airways. http://www.maths.gla.ac.uk/~pstewart

Abstract
Experiments indicate that a monolayer of gas-liquid foam confined within a Hele-Shaw cell can exhibit brittle fracture when subject to an applied driving pressure. In this talk we characterise this brittle fracture mode by considering the propagation of an internally pressurised crack though a slab of elastic continuum material with low resistance to shear, extending the classical description of pressure-driven fracture in a linearly elastic material to a slab of finite-width. We employ a novel matched eigenfunction expansion approach to formulate the stress field, incorporating a global penalty term which we isolate by solving a Fredholm integral equation. We recover the well-known stress singularity in the neighbourhood of the crack tip, but demonstrate that the spatial extent of this stress field in the direction of the crack is set by the domain width irrespective of the shear modulus of the material. The versatility of this approach allows for considerable modifications in the physical properties of the fracturing material, including those characteristic of foams, where out-of-plane deflection of the structural elements and accompanying viscous resistance to motion over the plates of the Hele-Shaw cell are important. These modifications facilitate a solution of the continuum model in the limit of zero shear modulus, where the stress singularity is entirely absent and the lengthscale of the stress-field in the direction of the crack is instead set by the dissipation coefficients. We exploit this mis-match in lengthscales to construct an asymptotic description for a slender domain, analytically characterising the critical conditions for crack propagation as a function of the driving pressure and the domain width. Furthermore, we show that this outer asymptotic solution can be extended to describe materials with low but finite shear modulus, where the accompanying stress singularity around the crack tip is confined within a boundary layer adjacent to the crack surface.
 
 
 
 
Thu, 29 May 2025

11:00 - 12:00
C5

Fields with the absolute Galois group of Q

Jochen Koenigsmann
(University of Oxford)
Abstract
This is a report on work in progress aiming to prove the conjecture that if the absolute Galois group of a field K is isomorphic to that of \Q then K admits a (possibly trivial) henselian valuation with divisible value group and residue field \Q. What I can prove is that such a field K has a unique ordering and unique p-adic valuations, and that K satisfies Cebotarev's density theorem, Kronecker-Weber, Hasse-Minkowski, quadratic reciprocity etc.
We will show that our conjecture is equivalent to the birational version of Grothendieck's Section Conjecture over \Q, and we will discuss a model theoretic strengthening of our conjecture.
Wed, 28 May 2025
16:00
L6

Instanton homology for $\mathfrak{gl}_2$ webs and foams

Alex Epelde Blanco
(Harvard University)
Abstract

In the definition of the skein lasagna module of a $4$-manifold $X$, it is essential that the input TQFT be fully functorial for link cobordisms in $S^3 \times [0, 1]$. I will describe an approach to resolve existing sign ambiguities in Kronheimer and Mrowka's spectral sequence from Khovanov homology to singular instanton link homology. The goal is to obtain a theory that is fully functorial for link cobordisms in $S^3 \times [0,1]$, and where the $E_2$ page carries a canonical isomorphism to Khovanov-Rozansky $\mathfrak{gl}_2$ link homology. Possible applications include non-vanishing theorems for $4$-manifold Khovanov skein lasagna modules à la Ren-Willis.

Wed, 28 May 2025
11:00
L5

A central limit theorem and large deviations principle for the generalised Dean--Kawasaki equation with truncated noise on a bounded domain

Shyam Popat
(Mathematical Institute)
Abstract

We begin with motivation on how the study of SPDEs are relevant when interested in fluctuations of particle systems. 

We then present a law of large numbers, central limit theorem and large deviations principle for the generalised Dean--Kawasaki SPDE with truncated noise. 

Our main contribution is the ability to consider the equation on a general $C^2$-regular, bounded domain with Dirichlet boundary conditions. On the particle level the boundary condition corresponds to absorption and injection of particles at the boundary.

The work is based on discussions with Benjamin Fehrman and can be found at https://arxiv.org/pdf/2504.17094 

 

Tue, 27 May 2025
16:00

Topological Invariants for G-kernels and Group Actions

Ulrich Pennig
Abstract

A G-kernel is a group homomorphism from a (discrete) group G to Out(A), the outer automorphism group of a C*-algebra A. There are cohomological obstructions to lifting such a G-kernel to a group action. In the setting of von Neumann algebras, G-kernels on the hyperfinite II_1-factor have been completely understood via deep results of Connes, Jones and Ocneanu. 

In the talk I will explain how G-kernels on C*-algebras and the lifting obstructions can be interpreted in terms cohomology with coefficients in crossed modules. G-kernels, group actions and cocycle actions then give rise to induced maps on classifying spaces. For strongly self-absorbing C*-algebras these classifying spaces turn out to be infinite loop spaces creating a bridge to stable homotopy theory.

The talk is based on joint work with S. Giron Pacheco and M. Izumi, and with my PhD student V. Bianchi.
 

Tue, 27 May 2025
16:00

Resurgence and arithmetic of q-series: from quantum operators to quantum modular forms

Claudia Rella
(Institut des Hautes Etudes Scientifiques)
Abstract

Perturbative expansions in quantum theory, particularly in quantum field theory and string theory, are typically factorially divergent due to underlying non-perturbative sectors. Resurgence provides a universal toolbox to access the non-perturbative effects hidden within the perturbative series, producing a collection of exponentially small corrections. Under special assumptions, the non-perturbative data extracted via resurgent methods exhibit intrinsic number-theoretic structures that are deeply rooted in the symmetries of the theory. The framework of modular resurgence aims to formalise this observation. In this talk, I will first introduce the systematic, algebraic approach of resurgence to the problem of divergences and describe the emerging bridge between the resurgence of q-series and the analytic and number-theoretic properties of L-functions and quantum modular forms. I will then apply it to the spectral theory of quantum operators associated with toric Calabi-Yau threefolds. Here, a complete realisation of the modular resurgence paradigm is found in the study of the spectral trace of local P^2, where the asymptotics at weak and strong coupling are captured by certain q-series, and is generalised to all local weighted projective planes. This talk is based on arXiv:2212.10606, 2404.10695, 2404.11550, and work to appear soon.



 

Tue, 27 May 2025
15:30
L4

Cored perverse sheaves

Vidit Nanda
(Oxford)
Abstract

I will describe some recent efforts to recreate the miraculous properties of perverse sheaves on complex analytic spaces in the setting of real stratified spaces.

Tue, 27 May 2025
15:00
L6

Coarse geometry of planar groups

Joe MacManus
Abstract

Virtually planar groups (that is, those groups with a finite-index subgroup admitting a planar Cayley graph) exhibit many fairly unique coarse geometric properties. Often, we find that any one of these properties completely characterises this class of groups. 

In this talk, I will survey some characterisations of virtually planar/virtual surface groups. Among other things, I will sketch why any group which is QI to a planar graph is necessarily virtually planar. Time permitting, I will discuss an upcoming new characterisation of virtual surface groups in terms of their coarse geometry. 

Tue, 27 May 2025
14:00
L6

Differential graded algebras with entire functional calculus

Jon Pridham
(Edinburgh University)
Abstract

(EFC-DGAs) lead to an algebraic approach to derived analytic geometry, pioneered for more general Fermat theories by Carchedi and Roytenberg.
 
They are well-suited to modelling finite-dimensional analytic spaces, and classical theorems in analysis ensure they give a largely equivalent theory to Lurie's more involved approach via pregeometries. DG dagger affinoid spaces provide a well-behaved class of geometric building blocks whose homotopy theory is governed by the underlying EFC-DGAs. 

Time permitting, I might also say a little about non-commutative generalisations.
 

Tue, 27 May 2025
13:00
L5

Monopoles, Dirac Strings and Generalised Symmetries

Chris Hull
(Imperial)
Abstract

Dirac’s quantum theory of magnetic monopoles requires a Dirac string attached to each monopole, and it is important that the field equations do not depend on the positions of the Dirac strings, provided that they comply with the Dirac veto: they must not intersect the worldliness of electrically charged particles. This theory is revisited, and it is shown that it has generalised symmetries related to the freedom of moving the Dirac strings. The Dirac veto is interpreted as an anomaly and the possibility of cancelling the anomaly by embedding in a higher-dimensional theory will be discussed. 

This talk is based on arXiv:2411.18741.

Tue, 27 May 2025

10:30 - 17:30
L3

One-Day Meeting in Combinatorics

Multiple
Further Information

The speakers are Yuval Wigderson (ETH Zurich), Liana Yepremyan (Emory), Dan Kráľ (Leipzig University and MPI-MiS), Marthe Bonamy (Bordeaux), and Agelos Georgakopoulos (Warwick). Please see the event website for further details including titles, abstracts, and timings. Anyone interested is welcome to attend, and no registration is required.

Mon, 26 May 2025
16:30
L4

Are $L^\infty$ solutions to hyperbolic systems of conservation laws unique?

Sam Krupa
(ENS Paris)
Abstract

For hyperbolic systems of conservation laws in 1-D, fundamental questions about uniqueness and blow up of weak solutions still remain even for the apparently “simple” systems of two conserved quantities such as isentropic Euler and the p-system. Similarly, in the multi-dimensional case, a longstanding open question has been the uniqueness of weak solutions with initial data corresponding to the compressible vortex sheet. We address all of these questions by using the lens of convex integration, a general method of constructing highly irregular and non-unique solutions to PDEs. Our proofs involve computer-assistance. This talk is based on joint work with László Székelyhidi, Jr.
 

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, 26 May 2025
15:30
L5

Relative Invertibility and Full Dualizability of Finite Braided Tensor Categories

Thibault Décoppet
(Harvard University)
Abstract

I will discuss an enriched version of Shimizu's characterizations of non-degeneracy for finite braided tensor categories. Using these characterizations, it follows that an enriched finite braided tensor category is invertible as an object of the Morita 4-category of enriched braided tensor categories if and only if it is non-degenerate. As an application, I will explain how to extend the full dualizability result of Brochier-Jordan-Synder by showing that a finite braided tensor category is fully dualizable in the Morita 4-category of braided tensor categories if its symmetric center is separable.
 

Mon, 26 May 2025
15:30
L3

Transport of Gaussian measures under the flow of semilinear (S)PDEs: quasi-invariance and singularity.

Dr. Leonardo Tolomeo
(University of Edinburgh)
Abstract

In this talk, we consider the Cauchy problem for a number of semilinear PDEs, subject to initial data distributed according to a family of Gaussian measures.  

We first discuss how the flow of Hamiltonian equations transports these Gaussian measures. When the transported measure is absolutely continuous with respect to the initial measure, we say that the initial measure is quasi-invariant. 

In the high-dispersion regime, we exploit quasi-invariance to build a (unique) global flow for initial data with negative regularity, in a regime that cannot be replicated by the deterministic (pathwise) theory.  

In the 0-dispersion regime, we discuss the limits of this approach, and exhibit a sharp transition from quasi-invariance to singularity, depending on the regularity of the initial measure. 

We will also discuss how the same techniques can be used in the context of stochastic PDEs, and how they provide information on the invariant measures for their flow. 

This is based on joint works with  J. Coe (University of Edinburgh), J. Forlano (Monash University), and M. Hairer (EPFL).

Mon, 26 May 2025
14:15
L5

Towards a gauge-theoretic approximation of codimension-three area

Alessandro Pigati
(Bocconi University)
Abstract

In the last three decades, a fruitful way to approximate the area functional in low codimension is to interpret submanifolds as the nodal sets of maps (or sections of vector bundles), critical for suitable physical energies or well-known lagrangians from gauge theory. Inspired by the situation in codimension two, where the abelian Higgs model has provided a successful framework, we look at the non-abelian SU(2) model as a natural candidate in codimension three. In this talk we will survey the new key difficulties and some recent partial results, including a joint work with D. Parise and D. Stern and another result by Y. Li.

Mon, 26 May 2025
13:00
L6

QFT-universality from String Theory

Maria Nocchi
Abstract

String-inspired methods have revealed deep connections between seemingly unrelated field theories. A striking example is the double copy structure, rooted in the string theory Kawai–Lewellen–Tye (KLT) relations. In this talk, we will explore how a variety of theories—including colored scalars, pions, and gluons—emerge from a single, unifying object: the KLT kernel. We will argue that this kernel is not only a powerful computational tool, but also a conceptually rich structure worthy of independent study.

Based mainly on https://arxiv.org/abs/1610.04230 and the recent work https://arxiv.org/abs/2505.01501.

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.

Fri, 23 May 2025

16:00 - 17:00
L1

From Physics-Informed Machine Learning to Physics-Informed Machine Intelligence: Quo Vadimus?

Prof. George Em Karniadakis
(Brown University)
Further Information

The Charles Pitts Robinson and John Palmer Barstow Professor of Applied Mathematics, Brown University;
Also @MIT & Pacific Northwest National Laboratory 

https://sites.brown.edu/crunch-group/

 

George Karniadakis is from Crete. He is an elected member of the National Academy of Engineering, member of the American Academy of Arts and Sciences, and a Vannevar Bush Faculty Fellow. He received his S.M. and Ph.D. from Massachusetts Institute of Technology (1984/87). He was appointed Lecturer in the Department of Mechanical Engineering at MIT and subsequently he joined the Center for Turbulence Research at Stanford / Nasa Ames. 

He joined Princeton University as Assistant Professor in the Department of Mechanical and Aerospace Engineering and as Associate Faculty in the Program of Applied and Computational Mathematics. He was a Visiting Professor at Caltech in 1993 in the Aeronautics Department and joined Brown University as Associate Professor of Applied Mathematics in the Center for Fluid Mechanics in 1994. After becoming a full professor in 1996, he continued to be a Visiting Professor and Senior Lecturer of Ocean/Mechanical Engineering at MIT. He is an AAAS Fellow (2018-), Fellow of the Society for Industrial and Applied Mathematics (SIAM, 2010-), Fellow of the American Physical Society (APS, 2004-), Fellow of the American Society of Mechanical Engineers (ASME, 2003-) and Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA, 2006-). He received the SES GI Taylor Medal (2024), the SIAM/ACM Prize on Computational Science & Engineering (2021), the Alexander von Humboldt award in 2017, the SIAM Ralf E Kleinman award (2015), the J. Tinsley Oden Medal (2013), and the CFD award (2007) by the US Association in Computational Mechanics. His h-index is 150 and he has been cited over 130,000 times.

 

Abstract

We will review physics-informed neural networks (NNs) and summarize available extensions for applications in computational science and engineering. We will also introduce new NNs that learn functionals and nonlinear operators from functions and corresponding responses for system identification. 

These two key developments have formed the backbone of scientific machine learning that has disrupted the path of computational science and engineering and has created new opportunities for all scientific domains. We will discuss some of these opportunities in digital twins, autonomy, materials discovery, etc.

Moreover, we will discuss bio-inspired solutions, e.g., spiking neural networks and neuromorphic computing.

 

 

Fri, 23 May 2025
13:00
L5

Stratified learning, cell biophysics, and material structures

Yossi Bokor Bleile
(IST Austria)

Note: we would recommend to join the meeting using the Teams client for best user experience.

Abstract

Geometry and topology call tell us about the shape of data. In this talk, I will give an introduction to my work on learning stratified spaces from samples, look at the use of persistent homology in cell biophysics, and apply persistence in understanding material structures.

Fri, 23 May 2025
12:00
L4

Calabi-Yau Varieties in Quantum Electrodynamics

Felix Forner
(TU Munich)
Abstract

The self-energies in Quantum Electrodynamics (QED) are not only fundamental physical quantities but also well-suited for investigating the mathematical structure of perturbative Quantum Field Theory. In this talk, I will discuss the QED self-energies up to the fourth order in the loop expansion. Going beyond one loop, where the integrals can be expressed in terms of multiple polylogarithms, we encounter functions associated with an elliptic curve, a K3 surface and a Calabi-Yau threefold. I will review the method of differential equations and apply it to the scalar Feynman integrals appearing in the self-energies. Special emphasis will be placed on the concept of canonical bases and on how to generalize them beyond the polylogarithmic case, where they are well understood. Furthermore, I will demonstrate how canonical integrals may be identified through a suitable integrand analysis.

Fri, 23 May 2025

12:00 - 13:00
Quillen Room

Representations of filtered but non integer-graded infinite-dimensional Lie algebras

Girish Vishwa
(University of Edinburgh)
Abstract

This talk will be a case study on the recently discovered boundary Carrollian conformal algebra (BCCA) in theoretical physics. It is an infinite-dimensional subalgebra of an abelian extension of the Witt algebra. A striking feature of this is that it is not integer graded; this already puts us in a rather novel setting, since infinite-dimensional Lie algebras almost exclusively appear with integer grading in physics. But this means that there is new ground to be broken in this direction of research. In this talk, I will present some very early results from our attempt at studying the representations of the BCCA. Any thoughts and comments are very welcome as they could be immensely helpful for us to navigate these unfamiliar waters!

Fri, 23 May 2025

11:00 - 12:00
L2

Modelling infectious diseases within-host

Dr Ruth Bowness
(Dept. Maths Science, University of Bath)
Abstract

During the talk I will describe my research on host-pathogen interactions during lung infections. Various modelling approaches have been used, including a hybrid multiscale individual-based model that we have developed, which simulates pulmonary infection spread, immune response and treatment within in a section of human lung. The model contains discrete agents which model the spatio-temporal interactions (migration, binding, killing etc.) of the pathogen and immune cells. Cytokine and oxygen dynamics are also included, as well as Pharmacokinetic/Pharmacodynamic models, which are incorporated via PDEs. I will also describe ongoing work to develop a continuum model, comparing the spatial dynamics resulting from these different modelling approaches.  I will focus in the most part on two infectious diseases: Tuberculosis and COVID-19.

Thu, 22 May 2025

17:00 - 18:00
L3

Axioms of Quantum Mechanics in the light of Continuous Model Theory​

Boris Zilber
(University of Oxford)
Abstract

I am going to start by reviewing axioms of quantum mechanics, which in fact give a description of a Hilbert space. I will argue that the language that Dirac and his followers developed is that of continuous logic and the form of axiomatisation is that of "algebraic logic" in the sense of A. Tarski's cylindric algebras. In fact, Hilbert spaces can be seen as a continuous model theory version of cylindric algebras.

Thu, 22 May 2025
16:00
L5

Liquidity Competition Between Brokers and an Informed Trader

Ryan Donnelly
(King's College London)
Abstract

We study a multi-agent setting in which brokers transact with an informed trader. Through a sequential Stackelberg-type game, brokers manage trading costs and adverse selection with an informed trader. In particular, supplying liquidity to the informed traders allows the brokers to speculate based on the flow information. They simultaneously attempt to minimize inventory risk and trading costs with the lit market based on the informed order flow, also known as the internalization-externalization strategy. We solve in closed form for the trading strategy that the informed trader uses with each broker and propose a system of equations which classify the equilibrium strategies of the brokers. By solving these equations numerically we may study the resulting strategies in equilibrium. Finally, we formulate a competitive game between brokers in order to determine the liquidity prices subject to precommitment supplied to the informed trader and provide a numerical example in which the resulting equilibrium is not Pareto efficient.

Thu, 22 May 2025
16:00
C3

Convergence of unitary representations of discrete groups

Michael Magee
(University of Durham)
Abstract

Let G be an infinite discrete group; e.g. free group, surface groups, or hyperbolic 3-manifold group.

Finite dimensional unitary representations of G of fixed dimension are usually very hard to understand. However, there are interesting notions of convergence of such representations as the dimension tends to infinity. One notion — strong convergence — is of interest both from the point of view of G alone but also through recently realized applications to spectral gaps of locally symmetric spaces. For example, this notion bypasses (unconditionally) the use of Selberg's Eigenvalue Conjecture in obtaining existence of large area hyperbolic surfaces with near-optimal spectral gaps. 

The talk is a broadly accessible discussion on these themes, based on joint works with W. Hide, L. Louder, D. Puder, J. Thomas, R. van Handel.

Thu, 22 May 2025
16:00
Lecture Room 4

Mordell–Weil groups of elliptic curves — beyond ranks

Alex Bartel
(University of Glasgow)
Abstract

If $E/\mathbb{Q}$ is an elliptic curve, and $F/\mathbb{Q}$ is a finite Galois extension, then $E(F)$ is not merely a finitely generated abelian group, but also a Galois module. If we fix a finite group $G$, and let $F$ vary over all $G$-extensions, then what can we say about the statistical behaviour of $E(F)$ as a $\mathbb{Z}[G]$-module? In this talk I will report on joint work with Adam Morgan, in which we investigate the simplest non-trivial special case of this very general question. Our work has surprising connections to questions about frequency of failure of the Hasse principle for genus 1 hyperelliptic curves, and to work of Heath-Brown on 2-Selmer group distributions in quadratic twist families.

Thu, 22 May 2025

15:00 - 16:00
L6

Exploring the $c$ - the conformal anomaly and spaces of field theories

Ludovic Fraser-Taliente
Abstract
$c$ is pretty cool. In two-dimensional critical theories, we are surrounded by it: it appears in the Virasoro central charge, the Stefan-Boltzmann constant, the conformal 'anomaly', the entanglement entropy, and at the endpoints of the Zamolodchikov $C$-function - and, of course, it doesn't appear on the string worldsheet. I will explain these appearances and the tight relationships between them, and discuss how we might use $c$ to chart and classify the space of CFTs and QFTs.


 

Junior Strings is a seminar series where DPhil students present topics of common interest that do not necessarily overlap with their own research area. This is primarily aimed at PhD students and post-docs but everyone is welcome.

Thu, 22 May 2025

14:00 - 15:00
Lecture Room 3

When you truncate an infinite equation, what happens to the leftovers?

Geoff Vasil
(University of Edinburgh)
Abstract

Numerically solving PDEs typically requires compressing infinite information into a finite system of algebraic equations. Pragmatically, we usually follow a recipe: “Assume solutions of form X; substitute into PDE Y; discard terms by rule Z.” In contrast, Lanczos’s pioneering “tau method” prescribes modifying the PDE to form an exact finite system. Crucially, any recipe-based method can be viewed as adding a small equation correction, enabling us to compare multiple schemes independently of the solver. 

This talk also addresses a paradox: PDEs often admit infinitely many solutions, but finite systems produce only a finite set. When we include a “small” correction, the missing solutions are effectively hidden. I will discuss how tau methods frame this perspective and outline proposals for systematically studying and optimising various residuals.

Thu, 22 May 2025

12:00 - 12:30
L4

Control of multistable structures with shape optimization

Arselane Hadj Slimane
(ENS Paris-Saclay)
Abstract

Shape optimization is a rich field at the intersection of analysis, optimization, and engineering. It seeks to determine the optimal geometry of structures to minimize performance objectives, subject to physical constraints—often modeled by Partial Differential Equations (PDEs). Traditional approaches commonly assume that these constraints admit a unique solution for each candidate shape, implying a single-valued shape-to-solution map. However, many real-world structures exhibit multistability, where multiple stable configurations exist under identical physical conditions.

This research departs from the single-solution paradigm by investigating shape optimization in the presence of multiple solutions to the same PDE constraints. Focusing on a neo-Hookean hyperelastic model, we formulate an optimization problem aimed at controlling the energy jump between distinct solutions. Drawing on bifurcation theory, we develop a theoretical framework that interprets these solutions as continuous branches parameterized by shape variations. Building on this foundation, we implement a numerical optimization strategy and present numerical results that demonstrate the effectiveness of our approach.

Thu, 22 May 2025
12:00
C6

Homogenisation for compressible fluids

Pierre Gonin-Joubert
(Université Claude Bernard Lyon 1)
Abstract

Several physical models are available to understand the dynamics of fluid mixtures, including the so-called Baer-Nunziato models. The partial differential equations associated with these models look like those of Navier-Stokes, with the addition of new relaxation terms. One strategy to obtain these models is homogenisation: starting from a mesoscopic mixture, where two pure fluids satisfying the compressible Navier-Stokes equations share the space between them, a change of scale is performed to obtain a macroscopic mixture, where the two fluids can coexist at any point in space.

This problem concerns the study of the Navier-Stokes equations with strongly oscillating initial data. We'll start by explaining some results in this framework, in one dimension of space and on the torus, for barotropic fluids. We will then detail the various steps involved in demonstrating homogenisation. Finally, we'll explain how to adapt this reasoning to homogenisation for perfect gases, with and without heat conduction.

Thu, 22 May 2025

12:00 - 13:30
L6

Superconformal algebras from superconformal structures

Ingmar Saberi
(Ludwig-Maximilians-Universität München)
Abstract

The notion of a superconformal structure on a supermanifold goes back some forty years. I will discuss some recent work that shows how these structures and their deformations govern supersymmetric and superconformal field theories in geometric fashion. A superconformal structure equips a supermanifold with a sheaf of dg commutative algebras; the tangent sheaf of this dg ringed space reproduces the Weyl multiplet of conformal supergravity (equivalently, the superconformal stress tensor multiplet), in any dimension and with any amount of supersymmetry. This construction is uniform under twists, and thus provides a classification of relations between superconformal theories, chiral algebras, higher Virasoro algebras, and more exotic examples.
 

Thu, 22 May 2025

12:00 - 13:00
L3

Accelerating Predictions of Turbulent Combustion and Nonequilibrium Flows Using Solver-Embedded Deep Learning

Jonathan MacArt
(Univ. of Notre Dame)
Further Information

Short Bio
Jonathan MacArt leads the Reacting Turbulence Lab, where he and his team develop high-performance computational tools to study how flow physics interact with phenomena like chemical heat release and plasma kinetics. Their work includes large-scale DNS, LES, RANS simulations, and physics-informed machine learning, with applications ranging from gas turbines to hypersonic propulsion systems.

Abstract

Predictions of complex flows remain a significant challenge for engineering systems. Computationally affordable predictions of turbulent flows generally require Reynolds-Averaged Navier–Stokes (RANS) simulations and Large-Eddy Simulation (LES), the predictive accuracy of which can be insufficient due to non-Boussinesq turbulence and/or unresolved multiphysics that preclude qualitative fidelity in certain regimes. For example, in turbulent combustion, flame–turbulence interactions can lead to inverse-cascade energy transfer, which violates the assumptions of many RANS and LES closures. We present an adjoint-based, solver-embedded data assimilation method to augment the RANS and LES equations using trusted data. This is accomplished using Python-native flow solvers that leverage differentiable programming techniques to construct the adjoint equations needed for optimization. We present applications to shock-tube ignition delay predictions, turbulent premixed jet flames, and shock-dominated nonequilibrium flows and discuss the potential of adjoint-based approaches for future machine learning applications.

 

Thu, 22 May 2025

11:00 - 12:00
C5

Modal group theory

Wojciech Wołoszyn
(University of Oxford)
Abstract

I introduce modal group theory, where one investigates the class of all groups using embeddability as a modal operator. By employing HNN extensions, I demonstrate that the modal language of groups is more expressive than the first-order language of groups. Furthermore, I establish that the theory of true arithmetic, viewed as sets of Gödel numbers, is computably isomorphic to the modal theory of finitely presented groups. Finally, I resolve an open question posed by Sören Berger, Alexander Block, and Benedikt Löwe by proving that the propositional modal validities of groups constitute precisely the modal logic S4.2.

Wed, 21 May 2025
17:30
Lecture Theatre 1

Blueprints: how mathematics shapes creativity - Marcus du Sautoy

Marcus du Sautoy
(University of Oxford)
Further Information

Many of the artists that we encounter are completely unaware of the mathematics that bubble beneath their craft, while some consciously use it for inspiration. Our instincts might tell us that these two subjects are incompatible forces with nothing in common, mathematics being the realm of precise logic and art being the realm of emotion and aesthetics. But what if we’re wrong?

Marcus du Sautoy unpacks how we make art, why a creative mindset is vital for discovering mathematics, and how a fundamental connection to the natural world intrinsically links the two subjects. 

Marcus du Sautoy is a mathematician, author and broadcaster. He is Charles Simonyi Professor for the Public Understanding of Science in Oxford.

Please email @email to register to attend in person.

The lecture will be broadcast on the Oxford Mathematics YouTube Channel on Wednesday 11 June at 5-6pm and any time after (no need to register for the online version).

The Oxford Mathematics Public Lectures are generously supported by XTX Markets.

Wed, 21 May 2025
16:00
L2

Fat minors and where to find them

Joseph MacManus
(University of Oxford)
Abstract

Recently, much attention has been paid to the intersection between coarse geometry and graph theory, giving rise to the fresh, exciting new field aptly known as ‘coarse graph theory’. One aspect of this area is the study of so-called ‘fat minors’, a large-scale analogue of the usual idea of a graph minor.

In this talk, I will introduce this area and motivate some interesting questions and conjectures. I will then sketch a proof that a finitely presented group is either virtually planar or contains arbitrarily ‘fat’ copies of every finite graph.

No prior knowledge or passion for graph theory will be assumed in this talk.

Wed, 21 May 2025
16:00
L6

(Seminar cancelled) Generalized Tate-Shafarevich groups over function fields

Tamás Szamuely
(Università degli studi di Pisa)
Abstract

Given a smooth geometrically connected curve C over a perfect field k and a smooth commutative group scheme G defined over the function field K of C, one can consider isomorphism classes of G-torsors locally trivial at completions of K coming from closed points of C. They form a generalized Tate-Shafarevich group which specializes to the classical one in the case when k is finite. Recently, these groups have been studied over other base fields k as well, for instance p-adic or number fields. Surprisingly, finiteness can be proven in some cases but there are also quite a few open questions which I plan to discuss  in my talk.

Wed, 21 May 2025
14:00
L3

Conformal welding and probability

Prof Steffen Rhode
(University of Washington)
Further Information

Please note: this seminar will be joint with the Mathematics of Random Systems CDT Workshop.

Abstract

Conformal welding, the process of glueing together Riemann surfaces along their boundaries, has recently played a prominent role in probability theory. In this talk, I will discuss two examples, namely the welding associated with random Jordan curves (SLE(k) loops) and particularly their limit as k tends to zero, and the welding of random trees (such as the CRT).

Wed, 21 May 2025
12:00
C1

On the converse of Pansu’s differentiability theorem

Andrea Merlo
(Universidad del País Vasco)
Abstract

In this talk I will present two new results concerning differentiability of Lipschitz maps between Carnot groups. The former is a suitable adaptation of Pansu-Rademacher differentiability theorem to general Radon measures. More precisely we construct a suitable bundle associated to the measure along which Lipschitz maps are differentiable, very much in the spirit of the results of Alberti-Marchese. The latter is the converse of Pansu’s theorem. Namely, let G be a Carnot group and μ a Radon measure on G. Suppose further that every Lipschitz map between G and H, some other Carnot group, is Pansu differentiable μ-almost everywhere. We show that μ must be absolutely continuous with respect to the Haar measure of G. This is a joint work with Guido De Philippis, Andrea Marchese, Andrea Pinamonti and Filip Rindler.

This new sub-Riemannian result will be an excuse to present and discuss the techniques employed in Euclidean spaces to prove the converse of Rademacher's theorem.

Tue, 20 May 2025

16:00 - 19:00
Glen Callater Room, H B Allen Centre, Keble College

Complexity Cluster Research Workshop

Abstract

The Complexity Cluster Event Organisers Professor Gui-Qiang G. Chen, Professor Helen Byrne, and Professor Mohit Dalwadi, cordially invite you to attend a Complexity Cluster Research Workshop on Tuesday, 20th May 2025, in the Glen Callater Room, H B Allen Centre, Keble College.

Complexity Cluster Research Workshop
Venue: Glen Callater Room, H B Allen Centre, Keble College
Date: Tuesday, 20th May 2025
Organisers: 
Professor Helen Byrne
Professor Gui-Qiang G. Chen
Professor Mohit Dalwadi
 

Programme:
4.00pm ̶ 4.15pm: Coffee, Drinks & Refreshments
4:15pm ̶ 4:40pm: Professor Didier Bresch (CNRS and Universite Savoie Mont-Blanc, France): Mathematical Topics around Granular Media
4:45pm – 5:10pm: Dr. Keith Chambers (Mathematical Institute, University of Oxford): Structured Population Models to Explore Lipid-Driven Macrophage Heterogeneity in Early Atherosclerotic Plaques
5:15pm ̶ 5:40pm: Coffee, Drinks & Refreshments
5:40pm ̶ 6:05pm: Dr. Tara Trauthwein (Department of Statistics, University of Oxford): Approximation Results for Large Networks
6:05pm-6:30pm: Isaac Newell (OxPDE, Mathematical Institute, University of Oxford): The Gauss Equation for Isometric Embeddings of Regularity in W1+2/3,3∩ C1
6:35pm-7:00pm: Discussion

For abstracts please click the file here: Complexity-Cluster_Workshop_20250212_Final_0.pdf