Oct 16 (Fri)
13:00 MCS2068 HEPMJoaquin Liniado (Edinburgh University): Holography for integrable field theories
Since its introduction, four-dimensional ChernSimons theory has offered a unifying origin for classically integrable field theories in two dimensions. However, the quantum aspects of this construction have remained largely mysterious. In this talk, I will present a first step in exploring this direction, based on a holographic construction in topological string theory.
Venue: MCS2068
Oct 19 (Mon)
13:00 MCS2068 ProbLoren Coquille (Université de Grenoble Alpes): Extremal Ising Gibbs States on non amenable graphs
On Z^2, the set of extremal states of the subcritical Ising model consists of the two pure « plus » and « minus » phases. On Z^3 is conjectured to be at most countable at low temperature. On a regular tree, it is known to be uncountable at low temperature. I will explain how to exhibit an uncountable family of extremal (non-automorphism invariant) Gibbs measures of the low temperature Ising model on non-amenable graphs. These states arise as low temperature perturbations of local ground states having a sparse enough set of frustrated edges, the sparseness being measured in terms of the isoperimetric constant of the graph. On regular tilings of the hyperbolic plane, our techniques allow to deduce extremality of uncountably many Series-Sinai states (having one interface along a continuous geodesic of H^2), and lead to the study of nice questions about hyperbolic billiards.
Based on joint works with Matteo DAchille, Christof Kuelske, Arnaud Le Ny and Jean Vereecke.
Venue: MCS2068
Oct 20 (Tue)
14:00 MCS2068 APDEOfelia Bonesini (London School of Economics): Continuous-time persuasion by filtering
We frame dynamic persuasion in a partial observation stochastic control Leader-Follower game with an ergodic criterion. The Receiver controls the dynamics of a multidimensional unobserved state process. Information is provided to the Receiver through a device designed by the Sender that generates the observation process. The commitment of the Sender is enforced. We develop this approach in the case where all dynamics are linear and the preferences of the Receiver are linear-quadratic. We prove a verification theorem for the existence and uniqueness of the solution of the HJB equation satisfied by the Receiver's value function. An extension to the case of persuasion of a mean field of interacting Receivers is also provided. We illustrate this approach in two applications: the provision of information to electricity consumers with a smart meter designed by an electricity producer; the information provided by carbon footprint accounting rules to companies engaged in a best-in-class emissions reduction effort. In the first application, we link the benefits of information provision to the mispricing of electricity production. In the latter, we show that even in the absence of information cost, it might be optimal for the regulator to blur information available to firms to prevent them from coordinating on a higher level of carbon footprint to reduce their cost of reaching a below average emission target. This is a joint work with René Aïd, Giorgia Callegaro and Luciano Campi.
Venue: MCS2068
Oct 23 (Fri)
13:00 MCS2068 HEPMEnoch Leung (Durham University): Resolving Continuous Symmetries in Holography
We study topological operators that generate continuous symmetries in the context of holography. Such operators can be modeled as solitonic branes in the supergravity bulk, whose ends are anchored on the conformal boundary with a finite separation. This holographic realization mirrors the field-theoretic regularization of symmetry operators in terms of objects with finite thickness and tension. We further discuss how these objects measure the charge of Wilson lines ending on the boundary. Despite sharing similar low-energy physics, the top-down descriptions of such hanging branes generally differ, depending on the UV completion of the bulk theory, and on the geometric origins of the symmetries involved.
Venue: MCS2068
14:00 MCS2068 G&TYuri Santos Rego (Lincoln): Measuring the width of annuli in groups of isometries of
Euclidean space
The classical isoperimetric inequality led us to investigate
'filling area functions' on manifolds. But when looking at free
homotopies between loops, calculating the width of annuli bounded by
simple closed curves is the geometric problem analogous to the
computation of filling functions. In Poincaré's spirit of doing geometry
by studying fundamental groups, the Dehn function plays the role of the
filling area function. As it turns out, the "annuli width" function also
has a group-theoretic counterpart: the Conjugator Length Function (CLF).
In this talk we shall discuss the growth rate of CLF for locally compact
groups, along with some basic properties and the current state of
knowledge (focusing on discrete groups). We shall see examples showing
that the width of annuli changes wildly even under quasi-isometries,
along with a classification of (the growth rate of) CLF for locally
compact split groups of isometries of Euclidean space.
Based on joint work with Petra Schwer.
Venue: MCS2068
Click on title to see abstract.
Back to Homepage
These events are hosted in and/or organised by members of the Department (follow links for details):
Oct 16 [Kenworthy Hall, St Mary's] Willmore Day 2026
Speakers: A Barber, L Dahlmeier, D Disney, S Mohapatra, J Quijas, F Salerno, S Shepherd
Venue: Kenworthy Hall, St Mary's at/from 09:30
Oct 19 [CB0011] LMS Tropical Mathematics and its Applications
Click on series to expand.
Usual Venue: MCS2068
Contact: yohance.a.osborne@durham.ac.uk
Oct 20 14:00 Ofelia Bonesini (London School of Economics): Continuous-time persuasion by filtering
We frame dynamic persuasion in a partial observation stochastic control Leader-Follower game with an ergodic criterion. The Receiver controls the dynamics of a multidimensional unobserved state process. Information is provided to the Receiver through a device designed by the Sender that generates the observation process. The commitment of the Sender is enforced. We develop this approach in the case where all dynamics are linear and the preferences of the Receiver are linear-quadratic. We prove a verification theorem for the existence and uniqueness of the solution of the HJB equation satisfied by the Receiver's value function. An extension to the case of persuasion of a mean field of interacting Receivers is also provided. We illustrate this approach in two applications: the provision of information to electricity consumers with a smart meter designed by an electricity producer; the information provided by carbon footprint accounting rules to companies engaged in a best-in-class emissions reduction effort. In the first application, we link the benefits of information provision to the mispricing of electricity production. In the latter, we show that even in the absence of information cost, it might be optimal for the regulator to blur information available to firms to prevent them from coordinating on a higher level of carbon footprint to reduce their cost of reaching a below average emission target. This is a joint work with René Aïd, Giorgia Callegaro and Luciano Campi.
Venue: MCS2068
Oct 27 14:00 Dante Kalise (Imperial College London): Stabilising Feedback Laws for Mean-Field Control and Global Optimisation
We look at feedback control of large systems of interacting particles. In the mean-field limit, this becomes the stabilisation of McKeanVlasov PDEs. When the free energy is non-convex, the target states may be unstable or reached only very slowly. We linearise the Wasserstein gradient flow around the target and act on its finitely many slow or unstable modes. This gives a Riccati feedback law that locally exponentially stabilises the full nonlinear dynamics, and it can be seen as a local convexification of the free energy.
The same idea applies to consensus-based optimisation (CBO), which is itself a McKeanVlasov particle system whose target is the global minimiser. We treat global optimisation as an optimal stabilisation problem and add a stabilising feedback, obtained from the associated HJB equation, to the CBO dynamics. Convergence becomes faster and more robust, including in high dimensions.
Based on joint works with M. Herty, Y. Huang, N. Kantas, H. Kouhkouh, L. Moschen and G. A. Pavliotis.
Venue: MCS2068
Usual Venue: MCS3070
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: OC218
Contact: mohamed.anber@durham.ac.uk
For more information, see HERE.
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS3052
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS3070
Contact: yi-lok-enoch.leung@durham.ac.uk
Oct 28 13:00 Oscar Lewis (University of Oxford): TBA
Nov 23 10:00 Benjamin Muntz (University of Nottingham): TBA
Dec 09 13:00 Alonso Perez-Lona (Max Planck Institute for Mathematics in the Sciences): TBA
Usual Venue: MCS2068
Contact: martin.p.kerin@durham.ac.uk
Oct 23 14:00 Yuri Santos Rego (Lincoln): Measuring the width of annuli in groups of isometries of
Euclidean space
The classical isoperimetric inequality led us to investigate
'filling area functions' on manifolds. But when looking at free
homotopies between loops, calculating the width of annuli bounded by
simple closed curves is the geometric problem analogous to the
computation of filling functions. In Poincaré's spirit of doing geometry
by studying fundamental groups, the Dehn function plays the role of the
filling area function. As it turns out, the "annuli width" function also
has a group-theoretic counterpart: the Conjugator Length Function (CLF).
In this talk we shall discuss the growth rate of CLF for locally compact
groups, along with some basic properties and the current state of
knowledge (focusing on discrete groups). We shall see examples showing
that the width of annuli changes wildly even under quasi-isometries,
along with a classification of (the growth rate of) CLF for locally
compact split groups of isometries of Euclidean space.
Based on joint work with Petra Schwer.
Venue: MCS2068
Oct 30 14:00 Dirk Schütz (Durham): TBA
Nov 06 14:00 David Lanners (Durham): TBA
Nov 13 14:00 Michael Kohn (Durham): \( \mathfrak{sl}_p \)-homology over \( \mathbb{F}_p \)
\( \mathfrak{sl}_N \) homology is a quantum invariant of
knots and links, generalising Khovanov homology. In this talk we will
provide a brief introduction to how this is defined via objects called
foams. We will also introduce s-invariants, which have applications in
4-manifold topology. We will then show that for the case of N a prime p,
and working over \( \mathbb{F}_p \), the chain complex that this theory
associates to a link diagram has a remarkably simple decomposition. From
this, we can deduce new results and reprove existing results regarding
s-invariants and the structure of \( \mathfrak{sl}_p \) homology.
Venue: MCS2068
Nov 20 14:00 Luke Jeffreys (Bristol): TBA
Nov 20 15:00 Philipp Bartmann (Potsdam): TBA
Nov 27 14:00 Emily Roff (Edinburgh): TBA
Dec 04 14:00 Simon Willerton (Sheffield): TBA
Jan 29 14:00 Marco Radeschi (Torino): TBA
Feb 12 14:00 Kasia Wyczesany (Leeds): TBA
Usual Venue: MCS2068
Contact: p.e.dorey@durham.ac.uk,parita.r.shah@durham.ac.uk,tobias.p.hansen@durham.ac.uk
Oct 16 13:00 Joaquin Liniado (Edinburgh University): Holography for integrable field theories
Since its introduction, four-dimensional ChernSimons theory has offered a unifying origin for classically integrable field theories in two dimensions. However, the quantum aspects of this construction have remained largely mysterious. In this talk, I will present a first step in exploring this direction, based on a holographic construction in topological string theory.
Venue: MCS2068
Oct 23 13:00 Enoch Leung (Durham University): Resolving Continuous Symmetries in Holography
We study topological operators that generate continuous symmetries in the context of holography. Such operators can be modeled as solitonic branes in the supergravity bulk, whose ends are anchored on the conformal boundary with a finite separation. This holographic realization mirrors the field-theoretic regularization of symmetry operators in terms of objects with finite thickness and tension. We further discuss how these objects measure the charge of Wilson lines ending on the boundary. Despite sharing similar low-energy physics, the top-down descriptions of such hanging branes generally differ, depending on the UV completion of the bulk theory, and on the geometric origins of the symmetries involved.
Venue: MCS2068
Oct 30 13:00 Ruth Gregory (Kings College London): TBA
Nov 06 13:00 Hugh Osborn (Cambridge University): TBA
Nov 13 13:00 Anton Kapustin (Caltech): Locality, higher symmetries, and anomalies: an operator-algebraic approach
In the usual Euclidean path-integral picture, higher symmetries are represented by invertible topological defects, and ’t Hooft anomalies are described by anomaly inflow from a topological action in one dimension higher. Is there a corresponding construction that starts directly from the algebra of local operators and its symmetries? To address this question, I will describe a mathematically precise framework based on localized symmetry transformations and their commutators. To each spatial region U, one associates a group of transformations localized in U. Locality implies that the commutator of transformations localized in regions U and V is localized in their intersection. From these data one can extract a system of higher groups, one per cover of space. Both anomalies and higher symmetries are encoded in this system of higher groups. The framework is designed to treat algebraic QFT and quantum lattice systems in a common language. The guiding idea is that topology emerges from the interplay of symmetry and locality.
Venue: MCS2068
Nov 20 13:00 Prahar Mitra (Southampton University): TBA
Nov 27 13:00 Mariana Carrillo Gonzalez (Southampton University): TBA
Dec 04 13:00 Daniel Brennan (University of Birmingham): TBA
Dec 11 13:00 Alessandro Georgoudis (Queen Mary University of London): TBA
Usual Venue: MCS2068
Contact: tyler.helmuth@durham.ac.uk,oliver.kelsey-tough@durham.ac.uk
Oct 19 13:00 Loren Coquille (Université de Grenoble Alpes): Extremal Ising Gibbs States on non amenable graphs
On Z^2, the set of extremal states of the subcritical Ising model consists of the two pure « plus » and « minus » phases. On Z^3 is conjectured to be at most countable at low temperature. On a regular tree, it is known to be uncountable at low temperature. I will explain how to exhibit an uncountable family of extremal (non-automorphism invariant) Gibbs measures of the low temperature Ising model on non-amenable graphs. These states arise as low temperature perturbations of local ground states having a sparse enough set of frustrated edges, the sparseness being measured in terms of the isoperimetric constant of the graph. On regular tilings of the hyperbolic plane, our techniques allow to deduce extremality of uncountably many Series-Sinai states (having one interface along a continuous geodesic of H^2), and lead to the study of nice questions about hyperbolic billiards.
Based on joint works with Matteo DAchille, Christof Kuelske, Arnaud Le Ny and Jean Vereecke.
Venue: MCS2068
Usual Venue: MCS2068
Contact: alexander.mangerel@durham.ac.uk
Nov 02 16:00 Francesco Lin (Columbia): TBA
Nov 24 13:00 Giannis Platis (Patras): TBA
Dec 01 13:00 Rob Kurinczuk (Sheffield): TBA
Jan 27 13:00 Marco Radeschi (Torino): TBA
Feb 09 13:00 Tim Browning (UCL): TBA
Feb 23 13:00 Tara Brendle (Glasgow): TBA
Mar 16 13:00 Rémi Coulon (Dijon): TBA
Usual Venue: MCS3070
Contact: joe.thomas@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
