Keynote speakers

Alain Chenciner

Professeur émérite Université Paris 7, chercheur associé à l'Observatoire de Paris


Alain Chenciner was born in 1943 in France. He studied at Ecole Polytechnique from 1963 to 1965, and received his Doctorat d’Etat from Université Paris XI in 1971. He is currently emeritus professor at University Paris 7 and is associated to the Paris Observatory. In 1992 he created with Jacques Laskar the research group Astronomie et Systèmes Dynamiques inside the Bureau des Longitudes, now hosted by Paris Observatory..

He was an invited speaker at ICM Beijing 2002 and a plenary speaker at ICMP Lisbon 2003.

His research has been mainly devoted to bifurcation theory, and to the n-body problem.

Keynote address: n-body relative equilibria in higher dimensions

If one allows the dimension of the ambient Euclidean space to be greater than 3, the family of n-body configurations which, when submitted to Newtonian or similar attraction, admit a relative equilibrium motion (the ``balanced" configurations) becomes much richer. Also, a given balanced configuration admits a variety of relative equilibria, namely one for each choice of a Hermitian structure on the space where the motion really takes place; in general, if the configuration is not central, such relative equilibria are quasi-periodic.

I shall give an overview of balanced configurations and discuss some problems, like the one of deciding what is the smallest dimension in which a given configuration admits a relative equilibrium motion, or when bifurcations from periodic to quasi-periodic relative equilibrium may occur.

Keynote References

  • A. Albouy & A. Chenciner, Le problème des n corps et les distances mutuelles, Inventiones Mathematicae, 131, pp. 151-184 (1998)
  • A. Chenciner, The Lagrange reduction of the N-body problem: a survey, Acta Mathematica Vietnamica (2013) 38: 165-186,
  • A. Chenciner, The angular momentum of a relative equilibrium, Discrete and Continuous Dynamical Systems (dedicated to the memory of Ernesto Lacomba)  (2012), Volume 33, Number 3, March 2013, 1033-1047
  • A. Chenciner & H. Jiménez-Pérez, Angular momentum and Horn's problem,  Moscow Mathematical Journal, Volume 13, Number 4, October-December 2013, 621-630
  • A. Chenciner, Non-avoided crossings for n-body balanced configurations in R^3 near a central configuration, Arnold Math J. (2016) n°2, 213-248

Elena Celledoni

Professor at Department of Mathematical Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway


Elena Celledoni received her Master degree in mathematics from the University of Trieste in 1993, and her Ph.D in computational mathematics from the University of Padua, Italy, 1997. She held post doc positions at the University of Cambridge, UK, at the Mathematical Sciences Research Institute, Berkeley, California and at NTNU.
Her research field is in numerical analysis and in particular structure preserving algorithms for differential equations and geometric numerical integration.

Keynote Address: Structure preserving algorithms for geometric numerical integration

Keynote References

  • E Celledoni, S Eidnes, B Owren, T Ringholm, Energy preserving methods on Riemannian manifolds , arXiv preprint arXiv:1805.07578
  • Elena Celledoni, Sølve Eidnes, Brynjulf Owren, and Torbjørn Ringholm, Dissipative Numerical Schemes on Riemannian Manifolds with Applications to Gradient Flows, SIAM J. Sci. Comput., 40(6), A3789–A3806.
  • E Celledoni, S Eidnes, A Schmeding, Proceedings of the Abel Symposium 2016, Springer, Shape analysis on homogeneous spaces: a generalised SRVT framework
  • E Celledoni, M Eslitzbichler, A Schmeding, Shape Analysis on Lie Groups with Applications in Computer Animation , Journal of Geometric Mechanics (JGM). 8 (3)

Karl Friston

University College of London

Keynote Address: Free-Energy & Brain Gauge Theory (Title to be confirmed)

Gabriel Peyré

CNRS and Ecole Normale Supérieure


Gabriel Peyré is senior researcher at the Centre Nationale de Recherche Scientifique (CNRS) and professor at the Ecole Normale Supérieure, Paris. His research is focused on developing mathematical and numerical tools for imaging sciences and machine learning. He is the creator of the "Numerical tour of data sciences" (, a popular online repository of Python/Matlab/Julia/R resources to teach mathematical data sciences. His research was supported by a ERC starting grant (SIGMA-Vision, 2010-2015) and is now supported by a ERC consolidator grant (NORIA 2017-2021). He is the 2017 recipient of the Blaise-Pascal prize from the French Academy of sciences, awarded each year to a young applied mathematician.

Keynote address:  Optimal Transport for Machine Learning

Optimal transport (OT) has become a fundamental mathematical tool at the interface between calculus of variations, partial differential equations and probability. It took however much more time for this notion to become mainstream in numerical applications. This situation is in large part due to the high computational cost of the underlying optimization problems. There is a recent wave of activity on the use of OT-related methods in fields as diverse as image processing, computer vision, computer graphics, statistical inference, machine learning. In this talk, I will review an emerging class of numerical approaches for the approximate resolution of OT-based optimization problems. This offers a new perspective for the application of OT in high dimension, to solve supervised (learning with transportation loss function) and unsupervised (generative network training) machine learning problems.
Keynote References

Jean-Baptiste Hiriart-Urruty

Toulouse University

Keynote address:  Fermat, Pascal & the Geometry of Chance (Title to be confirmed)