Archive | Meetings

Understanding the Structure of Liquids: Celebrating John Enderby’s Scientific Legacy.

About the workshop:

This Workshop, organised by the Liquids and Complex Fluids Group and the Neutron Scattering Group of the Institute of Physics, will celebrate the scientific contributions of Sir John Enderby FRS (1931-2021).

John was a pioneer in using neutrons to study the structure of disordered matter. In 1966, together with Peter Egelstaff and David North, John introduced the technique of neutron scattering with isotopic substitution which advanced fundamental understanding of multicomponent liquids, including liquid alloys, glasses, liquid semiconductors and molten salts. Different isotopes scatter neutrons in different ways allowing the correlations between different species to be unravelled. This technique, and John’s ability to exploit it using newly developed neutron sources, proved enormously productive in determining the physics of a huge variety of liquid and glassy systems. An early application by John and colleagues determined how water molecules are ordered around ions in aqueous solutions- a major step forward in chemical physics. John was an inspirational research leader and an exceptional servant to the wider scientific community. He served with distinction as Physical Secretary of the Royal Society from 1999 to 2004 and as President of the Institute of Physics from 2004 to 2006.

The meeting will feature contributions from some of John’s former colleagues and students as well as talks on current research on the structure of liquids illustrating how John’s work and the techniques he developed influence the field.

Speakers include :  A. Barnes (Bristol) , J. Drewitt (Bristol), T. Headen (RAL)  J. Finney (UCL), P. Mason (Prague), H. Mohammadi (Bath), G. Neilson (Bristol) , R. Newport (Kent) , P. Salmon (Bath), A. Soper (RAL).

Please visit the main event website for the full programme and information on how to register.

Sir John Enderby leans over some scientific equipment and smiles warmly at the camera. He is an older white man with glasses, and looks happy and excited.

Sir John Enderby

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Heilbronn Colloquium 2022: Goulnara Arzhantseva

Wednesday 13th July 2022: 16.00 – 17.00

We are delighted to welcome Professor Goulnara Arzhantseva, University of Vienna, to the University of Bristol to deliver a Heilbronn colloquium.

The colloquium with take place in Lecture theatre 2.41, Fry Building at 16:00 – 17:00 followed by a wine reception in the Fry Common Room.

Title: Approximations of infinite groups

Abstract: We discuss various still open questions on approximations of finitely generated groups, focusing on finite-dimensional approximations such as residual finiteness and soficity. We survey our results on the existence and stability of metric approximations. We suggest a few conjectures, e.g. on Gromov hyperbolic groups and their infinite monster limits. The setting is rather general and the involved concepts are transversal to various areas of mathematics.

Based on joint works with Liviu Paunescu (Bucharest).

 

The talks will be held in-person only. Spaces are limited in the room, so we ask that you please register via this form if you are intending to come in person. Once capacity is reached, we will close registration and any current remaining spaces will be allocated on a first come basis.


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Heilbronn Colloquium 2022: Tara Javidi

Wednesday 22nd June 2022: 16.00 – 17.00

University of Bristol

We are delighted to welcome Professor Tara Javidi, University of California, San Diego, to the University of Bristol to deliver a Heilbronn colloquium.

Title: Black-box Optimization in Theory and in Practice

Abstract: In this talk, we will consider the problem of maximizing a black-box function via noisy and costly queries from a theoretical perspective (a lot of it) as well as applications (an exciting bit). We motivate the problem by considering a wide variety of engineering design applications from the heuristic optimization of wireless networks to hardware acceleration to neural network architecture search.

We consider the problem in two settings where the blackbox function belongs to 1) the sample paths of a Gaussian Process or 2) a reproducing kernel Hilbert space (RKHS) with bounded norm. These settings, despite their seeming differences, rely on a Gaussian Process Bandit (GP-Bandit) interpretation of the problem. As a result, in much of prior work query point selection rule involves a bandit search over a sufficiently fine sequence of uniform discretization of the input space. In contrast, and inspired by a geometric (hypothesis testing) interpretation of optimization of continuous functions, we propose and analyze a new family of algorithms which adaptively discretize and zoom in the optimality region, resulting in a lower computational complexity, particularly when the domain is a subset of a high dimensional Euclidean space. In addition to the computational gains, sufficient conditions are identified under which the regret bounds of the new algorithm either improve upon the known results or asymptotically match the lower bound.

We end the talk by considering two important natural questions to which we provide partial answers. In particular, we quantify a lower bound on the gains obtained from a first-order oracle who in addition to zero-order oracle has access to (noisy) gradient information. Last not least, we discuss the extension of the framework to account for an instance-dependent regret analysis.

This is joint work with my former PhD student Shekhar Shubhanshu.

 

The colloquium with take place in Lecture theatre LG.02, Fry Building at 16:00 – 17:00 followed by a wine reception in the Fry Common Room.

The talks will be held in-person only. Spaces are limited in the room, so we ask that you please register via this form if you are intending to come in person. Once capacity is reached, we will close registration and any current remaining spaces will be allocated on a first come basis.


Join the Heilbronn Event mailing list to keep up to date with our upcoming events.

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Heilbronn Seminar Series 2022: Sanjay Shakkottai

IMPORTANT DATE UPDATE!

Monday 20th June 2022: 11.00 – 12.30 & 14.00 – 15.30

Tuesday 21st June 2022: 11.00 – 12.30 & 14.00 – 15.30

Friday 1st July 2022: 13.30 – 15.00

University of Bristol

We are delighted to welcome Professor Sanjay Shakkottai, University of Texas at Austin, to the University of Bristol to deliver a Heilbronn Seminar Series.

Title: Short Course on Causal Inference.

Abstract: Read more.

 

The seminars with take place in Lecture theatre 2.41, Fry Building.

The talks will be held in-person only. Spaces are limited in the room, so we ask that you please register via this form if you are intending to come in person. Once capacity is reached, we will close registration and any current remaining spaces will be allocated on a first come basis.


Join the Heilbronn Event mailing list to keep up to date with our upcoming events.

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Bristol Sequential Learning Workshop

Workshop details:

The Bristol Sequential Learning workshop is a two-day event to be held on the 23 and 24 of June, 2022. The workshop will provide an opportunity to discuss a broad range of research in the field of Sequential Learning, including Multi-Armed bandits, Reinforcement Learning, Active Learning, Sequential Hypothesis Testing and Change-point Detection.

Invited Speakers

The workshop will include talks from the following invited speakers:

  • Steffen Grunewalder (University of Lancaster)
  • Tara Javidi (University of California, San Diego)
  • Varun Kanade (University of Oxford)
  • Daniel Kious (University of Bath)
  • Tor Lattimore (DeepMind)
  • Omar Rivasplata (UCL)
  • Sanjay Shakkottai (University of Texas at Austin)
  • Vladislav Tadic (University of Bristol)
  • Sam Tickle (University of Bristol)
  • Sofia Villar (University of Cambridge)

Organisers

Ayalvadi Ganesh and Henry Reeve

Contributions

In addition, we welcome contributions from participants in the form of posters or lightning talks (including open problems). If you would like to contribute, please send an email to a.ganesh@bristol.ac.uk including the title of your contribution and whether you prefer to present a lightning talk or a poster.

Registration:

Registration is now closed.

Workshop costs:

Workshop:

  • Early career researcher (PhD student or postdoc): £25
  • Established researcher (permanent post): £25

Conference dinner (optional) -Dinner booking is now closed.

Travel

Re. Railway strikes: We are aware that the upcoming rail strikes will fall across the conference dates and are likely to cause widespread disruption (see link for details re. strike dates and lines affected). Although a reduced timetable will still be running, we would advise that, where possible, conference attendees look into alternative methods of transport or travel the day before to avoid the disruption. Attendees unable to reach the conference due to the strikes can contact the organisers to organise a refund of their registration/dinner costs.  

Accommodation

For planning purposes the workshop will be located within the Fry Building, postcode BS8 1UG. Information on accommodation options can be found by visiting the Visit Bristol website. 

Funding and support

This conference is made possible through the generous support of the Heilbronn Institute for Mathematical Research (HIMR) and the UK Research Innovation/ Engineering and Physical Sciences Research Council (UKRI/EPSRC) Additional Funding Programme for Mathematical Sciences.
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Heilbronn Annual Conference 2022

The Heilbronn Institute, University of Bristol, UK

The Heilbronn Annual Conference is the institute’s flagship event. It takes place over two days and it covers a broad range of mathematics, including algebra, combinatorics, data science, geometry, number theory, probability, quantum information. It brings together members of the Institute, distinguished visiting speakers, and other members of the UK mathematical community. This year we welcome eight distinguished speakers, to deliver lectures intended to be accessible to a general audience of mathematicians.

Invited Speakers:

Viviane Baladi (LPSM, Paris, France)
Jennifer Balakrishnan (Boston, USA)
Martin Bridson (Oxford, UK)
Toby Cubitt (UCL, UK)
Nicolas Curien (Paris-Sud Orsay, France)
Laure Saint-Raymond (ENS-Lyon, France)
Laura Schaposnik (Illinois, Chicago, USA)
Benny Sudakov (ETH, Zurich, Switzerland)

Visit the event site to register.

For more information please email the Heilbronn events team at  heilbronn-coordinator@bristol.ac.uk

Keep up to date with our upcoming events by joining the Heilbronn Event mailing list

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Heilbronn Colloquium 2022 – Andreas Strömbergsson

Tuesday 26th April 2022: 15.00 – 16.00

University of Bristol

We are delighted to welcome Andreas Strömbergsson, Uppsala University, as the Heilbronn Distinguished Visiting Professor, to deliver a Heilbronn Colloquium in person, at the University of Bristol in 2.04, Fry Building.

Title: Rational points on horospheres, random abelian Cayley graphs, and the Frobenius coin problem

Abstract: I will discuss a result about asymptotic equidistribution of certain point sets in the homogeneous space SL(d,Z)\SL(d,R), i.e. the space of lattices in the Euclidean space R^d. This result was first proved by Einsiedler, Mozes, Shah and Shapira (2016). As I will explain, the result has applications to limit laws for various metric parameters of random Cayley graphs of a large finite abelian group, and also to the so called Frobenius coin problem. I will discuss a new proof of the equidistribution result, which leads to an explicit rate of convergence. This proof makes use of tools from algebraic geometry (recent work of Erdelyi and Toth giving bounds on matrix Kloosterman sums) and tools from geometry of numbers (an integration formula by Rogers from 1955).

Joint work with Daniel El-Baz and Min Lee.

Spaces are limited in the room, so we ask that you please register via the form if you are intending to come in person. Once capacity is reached, we will close registration and any current remaining spaces will be allocated on a first come basis. The talk will be streamed via Zoom, but please note, it will be a basic stream and so not entirely interactive for those joining online. If you wish to attend via zoom please use the details below:

Join Zoom Meeting

Meeting ID: 957 5549 2327

Passcode: 826183

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Distinguished Lecture Series: Lauren Williams

11 – 13 April 2022 University of Bristol

We are very pleased to announce the 2022 Heilbronn Distinguished Lecture Series will be given by Lauren K Williams, Harvard University.

The talks will be held over three days in hybrid form at the School of Mathematics in the Fry Building:

Monday 11th April 2022 16.00, colloquium followed by a wine reception from 17.00

Tuesday 12th April 2022 16.00

Wednesday 13th April 2022 16.00

Please visit the event website to register

We are pleased to announce that we are able to consider applications for funding to support care costs*

This event is organised in collaboration with the University of Bristol

*Applies to expenses incurred exceptionally as a result of attending the lecture series. Please contact heilbronn-coordinator@bristol.ac.uk for further information.

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The charm of integrability – Honoring the scientific contributions of Alexander Its on the occasion of his 70th birthday

The goal of this conference is to bring together experts and young researchers, mathematicians and physicists, scientists with different backgrounds and different takes on integrable systems theory, to discuss the latest achievements in this dynamic field and to point at future research directions within the discipline. At the same time the meeting will serve to honour Alexander Its, a world renowned expert in the field, for his many ground-breaking contributions to the theory of integrable systems over the past 40 years, on the occasion of his 70th birthday.

The full list of invited speakers can be found below.

View the programme here.

The conference will be zoom live streamed. Please contact maths-conference-administrator@bristol.ac.uk for access details.

                           

 

Registration 

Registration has now closed.

 

Funding 

Limited funds are available for financial support, covering accommodation, and priority will be given to early career researchers, especially to those that will present a poster at the poster session. To be considered for financial support, participants are asked to complete the financial support form after completing their registration. Funding will be allocated on a first-come-first-serve basis. The last date to be considered for funding is August 26th.

 

Venue and accommodation 

The event will take place at the School of Mathematics, Fry Building, Woodland Road, Bristol. BS8 1UG.

Information on accommodation options can be found by visiting the Visit Bristol website. 

 

Invited speakers: 

Jinho Baik (University of Michigan)

Title: Multi-point distribution of (periodic) KPZ fixed points and differential equations

Abstract: The KPZ fixed point and its periodic version are two-dimensional random fields that are expected to be the universal limit of many random growth models and interacting particle systems. Their multi-point distributions were evaluated recently. We show that the involved Fredholm determinants can be expressed in terms of Its-Izergin-Korepin-Slavnov integrable operators. We then discuss the matrix integrable differential equations that these operators satisfy. These equations include matrix NLS with complex time, matrix mKdV, matrix KP, and multi-component KP hierarchy.

Estelle Basor (American Institute of Mathematics)

Title: Asymptotics of determinants of block Toeplitz matrices with symbols having jump discontinuities

Abstract: Well known classical theorems describe the asymptotics of finite Toeplitz matrices with scalar symbols of Fisher-Hartwig type. This talk will extend the classical results to the block case for symbols with jump discontinuities using an operator theory approach. 

Marco Bertola (Concordia University)

Title: Dim retrograde solitons and degenerate Riemann surfaces.

I will report on recent work with Alexander Tovbis and Bob Jenkins on how to compute effective formulas for the partial degeneration of Theta functions on nodal surfaces. As an application we provide the study of solitons on stationary  cnoidal background of the KdV equation. Some interesting physical phenomena include the fact that the “solitons” are now more like wave-packets with distinct group and phase velocities. The group velocity may be positive  (as usual) or negative (retrograde solitons). Moreover the explicit formula allows for the study of the soliton-on-soliton scattering matrix. 

Pavel Bleher (IUPUI School of Science)

Title: Ensembles of Random Matrices with Complex Potentials:Phase Diagrams and Topological Expansion

Abstract: We will discuss recent rigorous results on ensembles of random matrices withcomplex potentials, including topological expansion and phase diagrams in these ensembles inthe complex phase space of parameters. This is an ongoing project with Ahmad Barhoumi,Marco Bertola, Alfredo Dea ̃no, Roozbeh Gharakhloo, Ken McLaughlin, Alex Tovbis, andMaxim Yattselev.

Alexander Bobenko (Technische Universität Berlin)

Title: Integrability for geometry: Is a surface characterized by its metric and curvatures?

Abstract: We consider a classical problem in differential geometry, known as the Bonnet problem, whether a surface in three space is characterized by its metric and mean curvature function. Generically, the answer is yes. Special cases when it is not the case are classified. In the first part we consider Bonnet surfaces, which are surfaces (with non-constant mean curvature) possessing continuous families of isometries preserving mean curvature. Their global classification is given using the theory of Painleve equations. In the second part, which is a recent joint work with Tim Hoffmann and Andrew Sageman-Furnas, we explicitly construct a pair of immersed tori that are related by a mean curvature preserving isometry. Integrable systems play a crucial role in this construction. This resolves a longstanding open problem on whether the metric and mean curvature function determine a unique compact surface.

Mattia Cafasso (Université Angers)

Title:The finite temperature discrete Bessel kernel and integrable equations

Abstract: Using the theory of discrete integrable operators and discrete Riemann-Hilbert problems, I will show that the largest particle distribution of the point process associated to the finite-temperature discrete Bessel kernel satisfies some interesting integrable equations such as, for example, the cylindrical Toda equation. This is a joint work with Giulio Ruzza.

Tom Claeys (UCLouvain)

Title:Weak and strong confinement in the Freud random matrix ensemble

Abstract: Eigenvalues of unitary invariant random matrices confined by a Freud weight $|x|^\beta$ exhibit a transition between classical random matrix statistics and Poisson statistics as $\beta$ decreases. We describe the gap probabilities in this ensemble as a function of $\beta$. The talk will be based on joint work with I. Krasovsky and A. Minakov.

Peter Clarkson (University of Kent)

Title: Orthogonal Polynomials and Symmetric Sextic Freud weights

Abstract: In this talk I will discuss orthogonal polynomials associated with symmetric sextic Freud weights. In particular I will describe properties of the recurrence coefficients in the three-term recurrence relation associated with these orthogonal polynomials. These recurrence coefficients satisfy a fourth-order discrete equation which is the second member of the first discrete Painleve hierarchy, also known as the string equation, and also satisfies a coupled system of second-order, nonlinear differential equations. The weight arises in the context of Hermitian matrix models and random matrices.This is joint work with Kerstin Jordaan (University of South Africa) and Ana Loureiro (University of Kent).

Tamara Grava (University of Bristol)

Title: Gibbs ensemble for Integrable Systems and random matrices

We consider discrete integrable systems with random initial data and connect them with the theory of random matrices. We will consider the Toda lattice whose Gibbs ensemble has been connected by H. Spohn to the Gaussian beta-ensemble at high temperature. We then consider the defocusing nonlinear Schrodinger equation in its integrable version, that is called Ablowitz Ladik lattice. In the random initial data setting the Lax matrix of the Ablowitz Ladik lattice turns into a random matrix that is related to the circular beta-ensemble at high temperature. We obtain the density of states of the random Lax matrix, when the size of the matrix goes to infinity, by establishing a mapping to the one-dimensional log-gas. The density of states is obtained via a particular solution of the double-confluent Heun equation.

Jon Keating (University of Oxford)

Title: Multifractal eigenfunctions in intermediate systems

Abstract: I will discuss two systems that are intermediate between integrability and chaos, and for which the quantum eigenfunctions exhibit multifractal scaling. This is joint work with Henrik Ueberschär.

Vladimir Korepin (Stony Brook University)

Title: Lattice Nonlinear Schrodinger Equation

Abstract: History, applications and open problems will be considered.  We shall mainly pay attention to the quantum case.

Igor Krasovsky (Imperial College London)

Title: Asymptotics of the sine- and Airy-kernel determinants on two large intervals

Abstract: We consider the probability of 2 large gaps without eigenvalues in the local scaling limits in the bulk and at the edge of the spectrum of the Gaussian Unitary Ensemble of random matrices. We determine the multiplicative constants in the relevant asymptotics. In the bulk, the asymptotics without determination of the constant were found in 1997 by Deift, Its, and Zhou (in the general case of n gaps).

To obtain our results, we used a differential identity with respect to the gap edges and the observation that when the gaps are far apart, they are asymptotically independent, and so we can make use of the known constant for the one-gap asymptotics. The integration of the differential identity was the most challenging task due to theta-functions involved in the formulae. This is a joint work with Benjamin Fahs (sine-kernel) and Theo-Harris Maroudas (Airy-kernel).

Arno Kuijlaars (KU Leuven)

Title: Critical measures on higher genus Riemann surface

Abstract:I will report on recent work with Marco Bertola and Alan Groot on the definition and properties of critical measures on compact Riemann surfaces.

Our work is inspired by random tilings with periodic weights  that can be analyzed via matrix valued orthogonal polynomials. The matrix valued orthogonality can be viewed as scalar orthogonality on a Riemann surface, and the critical measures provide a step towards an understanding of their asymptotic behavior.

Oleg Lisovyy (Université de Tours)

Title: Perturbative connection formulas for Heun equations

Abstract: Connection formulas relating Frobenius solutions of linear ODEs at different Fuchsian singular points can be expressed in terms of the large order asymptotics of the corresponding power series. We demonstrate that for the usual, confluent and reduced confluent Heun equation, the series expansion of the relevant asymptotic amplitude in a suitable parameter can be systematically computed to arbitrary order. This allows to check a recent conjecture of Bonelli-Iossa-Panea Lichtig-Tanzini expressing the Heun connection matrix in terms of quasiclassical Virasoro conformal blocks.

Peter Miller (University of Michigan)

Title: On the algebraic solutions of the Painlev\’e-III (D$_7$) equation

Abstract: The D$_7$ degeneration of the Painlev\’e-III equation has solutions that are rational functions of $x^{1/3}$ for certain parameter values. We apply the isomonodromy method to obtain a Riemann-Hilbert representation of these solutions. We demonstrate the utility of this representation by analyzing rigorously the behavior of the solutions in the large parameter limit.  This is joint work with Robert Buckingham (Cincinnati).  If time permits, we will describe an interesting related calculation that we learned about 10 years ago from Alexander Its.

Beatrice Pelloni (Heriot Watt University)

Title: Novelty and surprises in the theory of third-order boundary value problems.

Abstract: I will review the results for differential operators an integrable PDEs of odd-order, when posed on bounded domains. The original  motivation for this work was the desire to understand the solution of a famous integrable PDE, the Kortweg-deVries equation.  The doors to these results  have been unlocked by the  understanding of the behaviour of linear third-order boundary values problems, that have been studied over the last 20 years by means of the Unified Transform. In some non-self-adjoint cases, this approach yields a spectral diagonalisation of the operator. More generally, I will highlight the  dependence of these problems on the specific boundary conditions and how this differs fundamentally from the even-order case. Novel and surprising examples arise for “Dirichlet-type” boundary conditions, as well as for quasi-periodic and time-periodic ones. I will also comment on some results for the nonlinear KdV case.

Nicolai Reshetikhin (University of California, Berkeley)

Title: Superintegrable systems on moduli spaces of flat connections.

Abstract: After a short review of superintegrability I will focus on superintegrable systems on moduli spaces of flat connections and on quantization of  these systems. Quantum Hamiltonians of such systems have simple meaning in terms of corresponding topological quantum field theory.

Nina Snaith (University of Bristol)

Title: A stochastic model for the spacing of replication origins on chromosomes

Abstract: In joint work with Huw Day we probe the statistical distribution of origins of DNA replication on eukaryotic chromosomes and develop a stochastic model for the replication process.

Leon Takhtajan (Stony Brook University)

Title: New supersymmetric localization principle

Abstract: I will present a new supersymmetric localization principle, with application to trace formulas for a full partition function. Unlike the standard localization principle, this new principle allowsto compute the supertrace of non-supersymmetric observables, and is based on the existence of fermionic zero modes. This is a joint work with Changha Choi, arXiv:2112.07942.

Self-similar fractal structures in tri-diagonal random matrices.

Self-similar fractal structure                                                                                                

Self-similar fractal structures in tri-diagonal random matrices.

Images of fractal structures courtesy of  Henry Taylor

Contacts 

Please contact Louisa Bartoszewicz regarding any administrative aspects of the conference. 

 

Organising committee:  

Thomas Bothner (University of Bristol) 

Tamara Grava (University of Bristol; International School for Advanced Studies (SISSA/IAS) 

Ken McLaughlin (Colorado State University) 

Andrei Prokhorov (University of Michigan) 

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Heilbronn Annual Conference 2021

The Heilbronn Institute for Mathematical Research welcomes eight distinguished speakers, to deliver lectures intended to be accessible to a general audience of mathematicians.

Invited speakers:

Caucher Birkar, University of Cambridge

Jon Brundan, University of Oregon

Ana Caraiani, Imperial College London

Heather Harrington, University of Oxford

Gil Kalai, Hebrew University of Jerusalem

Peter Keevash, University of Oxford

Jeremy Quastel, University of Toronto

Tatiana Smirnova-Nagnibeda, University of Geneva


To register please visit the event website. For more information email heilbronn-coordinator@bristol.ac.uk .

Join the Heilbronn Event mailing list to keep up to date with our upcoming events.

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