Meetings Archive

Heilbronn Annual Conference 2025

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. We have been fortunate to attract excellent speakers to our Annual Conferences since the Institute’s inception in 2005.

Registration opens Monday 17 March 2025

 

Contact information

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

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Heilbronn Distinguished Lecture Series 2025: Nalini Joshi (Sydney)

We are delighted to welcome Nalini Joshi, Payne-Scott Professor of Mathematics & the Chair of Applied Mathematics at the University of Sydney, who will deliver the next Distinguished Lecture Series (DLS) on 3 – 5 March 2025.

Nalini will be hosting three talks during her visit, including a colloquium-style lecture on Monday 3rd March which will be followed by a drinks reception. Talk titles and abstracts can be found below.

Registration is necessary, so please ensure to complete the registration form to secure your place.


Lecture 1: Monday 3 March 2025 at 16:15 [Colloquium] – followed by drinks reception.

Venue: Seminar Room 2.04, School of Mathematics, Fry Building, Woodland Road, Bristol BS8 1UG

Dynamics on and off elliptic curves (I)

Felix Klein said that the study of new transcendental functions defined by differential equations was “the central problem of the whole of modern mathematics”. The beginnings of this study lay in elliptic functions, which were generalised by the Painlevé transcendents. The analytic theory of their governing differential equations has a counterpart in the theory of the algebraic curves. The most famous examples are elliptic curves. What is not widely known is that the evolution of a solution of a Painlevé equation changes the underlying elliptic curve and points move from one such curve to another under its time evolution.  I will give an introductory overview of how this connects with their asymptotic behaviours and a simple model to describe how Boutroux (1913) initiated such asymptotic descriptions.

 

Lecture 2: Tuesday 4 March 2025 at 15:00

Venue: Seminar Room 2.04, School of Mathematics, Fry Building, Woodland Road, Bristol BS8 1UG

Dynamics on and off elliptic curves (II)

Starting with the simple model from the last lecture, I will describe behaviours in the limit as the independent variable approaches infinity, which are analogous to those seen in the Painlevé equations. Next, we give an overview of asymptotic results for the first Painlevé equation before describing how we deduced global results from a geometric description of the regularized projective space of initial values. The latter were carried out in collaboration with many co-authors: Duistermaat and Joshi (2011), Howes and Joshi (2014), Joshi and Radnovic (2016-2019), and Heu, Joshi and Radnovic (2023).

 

Lecture 3: Wednesday 5 March 2025 at 15:00

Venue: Seminar Room 2.04, School of Mathematics, Fry Building, Woodland Road, Bristol BS8 1UG

On q-difference Painlevé equations and their Riemann-Hilbert problems

A widely used method of studying such transcendental functions is through their formulation as Riemann-Hilbert problems, i.e., given functions in certain domains and jumps across their common boundaries, the problem of finding a global function that agrees with the given information. The formulation of a Riemann problem for difference equations was initiated by Birkhoff in 1913. In this talk, I will outline some recent results for q-Riemann-Hilbert problems and their ramifications for special functions that solve q-difference Painlevé equations.

About the Speaker: Nalini Joshi received her PhD from Princeton University with Martin Kruskal as her advisor. Her research focuses on integrable systems,  including the Painlevé equations, lattices and geometric asymptotics. Nalini was elected to the Australian Academy of Science as a Fellow in 2008, awarded a Georgina Sweet Australian Laureate Fellowship in 2012 and appointed Officer of the Order of Australia in 2016. She was President of the Australian Mathematical Society, Vice-President of the International Mathematical Union and is currently a member of its Executive Committee.

In the 2016 Queen’s Birthday honours, Nalini was appointed an Officer of the Order of Australia for distinguished service to mathematical science and tertiary education as an academic, author and researcher, to professional societies, and as a role model and mentor of young mathematicians.

Contact information

For practical information please email: heilbronn-coordinator@bristol.ac.uk

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Heilbronn Seminar – Professor Jesús María Sanz-Serna

Title: Split Hamiltonian Monte Carlo revisited

Abstract: Hamiltonian Monte Carlo (HMC) algorithms are widely used to generate samples from a given probability distribution. They are based on numerically integrating a Hamiltonian differential system, with the leapfrog/Verlet integrator being the integrator of choice. This integrator is based on splitting the Hamiltonian into its potential and kinetic parts. Often, probability distributions may be seen as a perturbation of a Gaussian. When using HMC algorithms to sample from those targets, it is tempting to alternatively split the Hamiltonian $H$ as $H_0(\theta,p)+U_1(\theta)$, where $H_0$ is quadratic and $U_1$ small and perform the required numerical integrations of the Hamiltonian dynamics by combining integrations for $H_0$ and integrations for $U_1$. This idea is appealing because, if $U_1$ were to vanish, the integration would be exact so that it may be hoped that for small $U_1$ the integration would be easy to perform. We will show that, unfortunately, samplers based on the $H_0+U_1$ splitting suffer from stepsize stability restrictions similar to those of algorithms based on the standard leapfrog integrator. The good news is that those restrictions may be circumvented by preconditioning the dynamics. Numerical experiments show that,  when the $H_0(\theta,p)+U_1(\theta)$ splitting is combined with preconditioning, it is possible to construct samplers far more efficient than  standard leapfrog HMC.

Biography

J.M. Sanz-Serna is an emeritus professor at Universidad Carlos III de Madrid. He has contributed to numerical analysis, approximation theory, functional analysis, Monte Carlo methods and other areas. His main interest has been in the numerical analysis of stochastic and deterministic, ordinary or partial differential equations. He served as Universidad of Valladolid Vicechancellor 1998-2006 and as President of the Royal Academy of Sciences of Spain 2018-2024.


The seminar will be held in room 2.04, Fry Building, 3pm – 4pm.

Professor Sanz-Serna will also host a colloquium talk on Wednesday 18th September. Further details can be found here.

For further information, please email the Heilbronn events team at  heilbronn-coordinator@bristol.ac.uk.
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Heilbronn Colloquium 2024: Professor Jesús María Sanz-Serna

Title: The Hamiltonian Monte Carlo method and Geometric Integration

Abstract: Generating samples from a given, possibly high-dimensional, probability distribution is a task that appears often in several sciences. The literature contains a high number of methods to perform that task and the talk will focus in one of them: the Hamiltonian Monte Carlo (HMC) algorithm. This widely used technique is remarkable in that it uses ideas from very many scientific fields, including classical mechanics, statistical physics and the theory of structure preserving discretizations of differential equations. The talk, which is aimed at a general audience and requires little background, will explore the connections between HMC and those different fields.

Biography

J.M. Sanz-Serna is an emeritus professor at Universidad Carlos III de Madrid. He has contributed to numerical analysis, approximation theory, functional analysis, Monte Carlo methods and other areas. His main interest has been in the numerical analysis of stochastic and deterministic, ordinary or partial differential equations. He served as Universidad of Valladolid Vicechancellor 1998-2006 and as President of the Royal Academy of Sciences of Spain 2018-2024.


The talk will be held in room 2.04, Fry Building. Registration is free, but required. Please register via the following form.

The colloquium will be followed by a drinks reception, 4pm – 5pm in the School of Mathematics common room.

Professor Sanz-Serna will also give a seminar on Monday 16th September. Further details can be found here.

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

 

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Heilbronn Colloquium 2024: Simon Foucart

Simon Foucart, Professor of Mathematics, Texas A & M University, USA
Heilbronn Distinguished Visiting Fellow, Isaac Newton Institute for Mathematical Sciences, UK

School of Mathematics, Woodland Road, Bristol BS8 1UG

Tuesday 2nd July 2024

4pm to 5pm

Room 2.04, Fry Building

Colloquium Title: Optimal Recovery as a Worst-Case Learning Theory

This talk showcases the speaker’s recent results in the field of Optimal Recovery, viewed as a trustworthy Learning Theory focusing on the worst case. At the core of several results presented here is a scenario, resolved in the global and the local settings, where the model set is the intersection of two hyperellipsoids. This has implications in optimal recovery from deterministically inaccurate data and in optimal recovery under a multifidelity-inspired model. In both situations, the theory becomes richer when considering the optimal estimation of linear functionals. This particular case also comes with additional results in the presence of randomly inaccurate data.

About the Speaker: Simon Foucart earned a Masters of Engineering from the Ecole Centrale Paris and a Masters of Mathematics from the University of Cambridge in 2001. He received his Ph.D. in Mathematics at the University of Cambridge in 2006, specializing in Approximation Theory. After two postdoctoral positions at Vanderbilt University and University of Paris 6, he joined Drexel University in 2010 before moving to the University of Georgia in 2013. He joined Texas A & M University in 2015 as an associate professor and he is currently a professor of Mathematics. His current work focuses on the modern field of Compressive Sensing, whose theory is exposed in the book ‘A Mathematical Introduction to Compressive Sensing‘ he co-authored with Holger Rauhut.

Simon’s research was recognised by the Journal of Complexity, from which he received the 2010 Best Paper Award. His interests also include the mathematical aspects of metagenomics.

Please  register here attend.

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

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

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Heilbronn Annual Conference 2024

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

Tara Brendle (University of Glasgow, UK)

Chaim Goodman-Strauss (Arkansas, USA)

Barbara M. Terhal (TU Delft, The Netherlands)

Richard Samworth (University of Cambridge, UK)

Josephine Yu (Georgia Institute of Technology, USA)

Christophe Breuil (Université Paris-Saclay, France)

Tim Austin (University of Warwick, UK)

Dipendra Prasad (Indian Institute of Technology Bombay, India)

 

Registration opens Monday 20th May 2024

Click here for more information

Email  heilbronn-coordinator@bristol.ac.uk

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Distinguished Visiting Professor 2024: Romain Tessera

Heilbronn colloquium: Romain Tessera

Romain Tessera, Senior Researcher, Université Paris Cité, France

Wednesday 8 May 2024 4pm to 5pm

Venue Lecture Theatre G.10, Fry Building

Followed by drinks reception 5-6pm in the Staff Common Room, Fry Building

Quantitative Ergodic Theory

Ergodic theory is the study of measure preserving actions of groups on a probability space. These may be studied from two different angles: up to isomorphism, or up to “orbit equivalence”. For the latter we merely require an isomorphism between the probability spaces that preserves the orbits of the group actions, but the groups themselves may no longer be isomorphic.

Orbit equivalence has been intensively studied since the eighties, and one of the most impressive results, due to Ornstein and Weiss, says that any two free ergodic actions of infinite amenable groups (such as Z^d for instance) are orbit equivalent. In other words, all information on the (amenable) groups is lost under orbit equivalence. We shall present a new theory, which emerged from the need to nuance Orstein-Weiss’ theorem. Roughly, one defines a way to measure how “good” an orbit equivalence map is in order to restore some information on the group.

Short biography

Romain Tessera defended his PhD in 2006 under the co-direction of Thierry Coulhon and Alain Valette. He then spent 2 years as a postdoctoral researcher at Vanderbilt University. Romain has been a researcher in CRNS (France) since 2008, first at École Normale Supérieure de Lyon, then at University of Orsay, and finally as a senior researcher at Université Paris Cité (since 2018). His research focuses on geometric group theory, with incursions in other fields such as ergodic theory, topological rigidity, non-commutative geometry.

 

Please register here to attend

Organised in collaboration with the School of Mathematics, University of Bristol, UK

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

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Heilbronn Colloquium 2024: Anna Frishman

Friday 12 April 2024 3pm to 4pm                                                                                                                                 

Anna Frishman, Distinguished Visiting Fellow, Cambridge University, UK and Physics Department, Technion, Israel

Lecture Theatre LG.02, Fry Building,  School of Mathematics, Woodland Road, Bristol BS8 1UG

Followed by a drinks reception 4pm to 5pm in the Staff Common Room, Fry Building.

Title: Universality of Satellite Formation During Breakup of a Fluid Bridge

The breakup of a fluid object is a remarkably singular process. Beautifully, the approach to this singularity can give rise to universal dynamics, occurring around the pinch off points. When breakup is driven by inertia in a symmetric configuration, the pinch off occurs symmetrically at two points, sealing off a satellite fluid drop.

Contrary to the dynamics at pinch off points, not much is known about universal dynamics for satellite formation.

Here we demonstrate the existence of such dynamics, leading to robust satellite sizes. Specifically, we consider the breakup of a slowly stretched fluid bridge, which we realize experimentally using a soap-film bubble suspended between two plates. Combining experiments and one-dimensional simulations, we show that a main satellite bubble always forms as the bridge breaks. We discover that the satellite size is a simple function of two non-dimensional control parameters, one dynamical and the other geometrical. These observations can be explained by tracing the bridge evolution over a series of dynamical stages in which the bridge: (i) closely follows a sequence of equilibrium bridge configurations; (ii) stretches as it begins to breakup after reaching an unstable equilibrium; and (iii) follows a universal breakup solution, occurring over a finite spatial region. We explain how stretching in stage (ii) controls the satellite volume, which varies with the control parameters over two orders of magnitude, and the universality of the dynamics makes it highly reproducible.

About the Speaker: Anna Frishman mainly works on turbulence, viewed as an out-of-equilibrium system at the intersection of fluid mechanics and statistical physics. From time to time, she works on problems in fluid mechanics without turbulence, and in statistical mechanics without fluids. Anna did her PhD in physics at the Weizmann Institute of Science under the supervision of Professor Gregory Falkovich, then moved to Princeton University for an independent postdoc at the PCTS. She has been a faculty member in the physics department at the Technion, Israel, since 2019.

Please register here to attend. 

 

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Heilbronn Seminar 2024: Daniel Wise

Daniel Wise, Department of Mathematics & Statistics, McGill University, Montreal, Canada

Friday 15 March 2024 at 13:00

[Lunch will be served at 12:00 in the Fry Building, Staff Common Room]

Venue: Lecture Theatre 2.41, Fry Building, School of Mathematics, University of Bristol, Bristol BS8 1UG

Organised in collaboration with the School of Mathematics, University of Bristol, UK

Registration is free, but required. Please register using this form.

A Small Contribution to the Kervaire Conjecture

I will give a quick survey of the known results and methods towards the Kervaire conjecture in combinatorial group theory. Then I will offer a small but pretty result that offers a new paradigm. This is joint work with Andy Ramirez-Côté.

 

 

Short Biography: Dani Wise grew up in New York and received his BA from Yeshiva University and his PhD from Princeton (1996). After stimulating postdocs and visiting positions at Berkeley, Cornell, and Brandeis, he moved to McGill in 2001, where he is a James McGill Professor. His primary research agenda has been to explore and promulgate the utility and ubiquity of non-positively curved cubical geometry in group theory and topology. He has received an AMS Veblen Prize, the CRM-Fields-PIMS Prize, a Guggenheim Fellowship, a Lobachevsky Medal, and is a Fellow of the Royal Society of London. Dani Wise is currently on Sabbatical at the Weizmann Institute of Science in Israel.

Professor Daniel Wise is also giving a Colloquium on Monday 11 March at 16:00 in Lecture Theatre 4, School of Chemistry.

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

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Heilbronn Colloquium 2024: Daniel Wise

Daniel Wise, Department of Mathematics & Statistics, McGill University, Montreal, Canada

Monday 11 March 2024 at 16:00

Venue: Lecture Theatre 4, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS

Organised in collaboration with the School of Mathematics, University of Bristol, UK

Registration is free, but required. Please register using this form

The Cubical Route to Understanding Groups

Cube complexes have come to play an increasingly central role within geometric group theory, as their connection to right-angled Artin groups provides a powerful combinatorial bridge between geometry and algebra. This talk will introduce nonpositively curved cube complexes, and then describe the developments that culminated in the resolution of the virtual Haken conjecture for 3-manifolds, and simultaneously dramatically extended our understanding of many infinite groups.

 

Short Biography: Dani Wise grew up in New York and received his BA from Yeshiva University and his PhD from Princeton (1996). After stimulating postdocs and visiting positions at Berkeley, Cornell, and Brandeis, he moved to McGill in 2001, where he is a James McGill Professor. His primary research agenda has been to explore and promulgate the utility and ubiquity of non-positively curved cubical geometry in group theory and topology. He has received an AMS Veblen Prize, the CRM-Fields-PIMS Prize, a Guggenheim Fellowship, a Lobachevsky Medal, and is a Fellow of the Royal Society of London. Dani Wise is currently on Sabbatical at the Weizmann Institute of Science in Israel.

Professor Daniel Wise is also giving a Seminar on Friday 15 March at 13:00 in Lecture Theatre 2.41, Fry Building.

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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