Interdisciplinary seminar

Since January 2022, discover monthly the interdisciplinary research activities of ITI IRMIA++ members.

The sessions will usually take place on the 3rd Thursday of each month at 9:00 (excepted during university breaks).
You can attend both at University (usually in IRMA conference room) and by visioconference.


Next sessions

22/09/2022 - Pierre Py (IRMA)  Morse theory and finiteness properties of groups and spaces


 IRMA Conference room and online :

Abstract: We will start the talk by recalling classical facts from Morse theory. In other words we will discuss the following classical question: what do the critical points of a function on a manifold tell us about the topology of the manifold? After that we will discuss the following question. Given a manifold M and a smooth map f from M to the circle, can we deform f to a map which has no critical points? Or a minimal number of critical points ?

About the speaker: Pierre Py is a CNRS junior researcher at IRMA. He graduated from ENS Lyon with a Ph.D. degree in 2008. After a postdoctoral stay at the University of Chicago, he joined IRMA as a CNRS researcher in 2011. His research interests evolved over time from the study of symplectic diffeomorphism groups towards Kähler geometry and its interactions with topology and geometric group theory.

20/10/2022 - Julien Narboux (ICube)  TBA



Abstract: TBA

About the speaker: TBA

24/11/2022 - Pierre Ocvirk (ObAS)  TBA



Abstract: TBA

About the speaker: TBA

Past sessions

23/06/2022 - Hubert Baty (ObAS)  Challenges in numerical modeling of magnetic reconnection in astrophysical/space plasmas

Abstract: I will present the state of the art on theoretical/numerical modelling of the magnetic reconnection process that is believed to be the central mechanism at work to explain magnetic eruptions in many astrophysical plasmas. In particular, I will highlight the main limitations when using standard numerical schemes to integrate the relevant set of partial differential equations in the magnetohydrodynamic framework. Finally, I will present hope for future numerical strategy based on machine/deep learning trough physics-informed neural networks.


About the speaker: Hubert Baty is Maître de Conférences at the University of Strasbourg, and pursues his research at the Observatoire astronomique de Strasbourg. His research focuses on instabilities and magnetic reconnection in magnetically-dominated plasmas with applications to solar/stellar corona and astrophysical jets.

19/05/2022 - Jonathan Sarton (ICube)  High performance visualization for large scale volume data

Abstract: Numerical simulations inevitably requires the use of modern visualization methods at different stages to analyze datasets, extract information from them, to guide phenomenon modeling, to validate or invalidate models or as a tool for evaluating experimental results. The access to increasingly powerful computing machines enables scientists to simulate ever larger and more complex phenomena. Large-scale simulations generally output time-varying multivariate volumetric data, modeled by volume meshes of increasingly complex size, topology, geometry, composition, ... Direct volume rendering (DVR) is a well known method for visualizing volume data and its implementation on graphics processors (GPU), based on volume ray-casting algorithm, offers good rendering quality combined to good performance. However, such an implementation on simulated data presenting above-mentioned characteristics is a difficult problem that remains open. A key challenge of research is to make visualization techniques follow up with this drastically increasing complexity.


After an introduction to volume rendering on GPU and its adaptation to large datasets, I will address the challenges of in-situ visualization of large and complex unstructured meshes from numerical simulation through the presentation of the ANR LUM-Vis project.

About the speaker: Jonathan Sarton is an associate professor at the University of Strasbourg in the computer science department, and the ICube Laboratory in the Computer Graphics and Geometry team (IGG).  His research focuses on high performance scientific visualization, volume rendering on GPU, parallel rendering, and in-situ visualization in HPC environment. He is the scientific leader of the LUM-Vis ANR project.

28/04/2022 - Semyon Klevtsov (IRMA)  Geometric test for topological phases of quantum matter

Abstract: Strongly-correlated quantum systems are often extremely fragile and notoriously hard to control, which poses challenges for possible technological applications. That is why a certain subclass of quantum states, the so-called topological phases of matter, recently attracted much attention. These are characterised by a certain degree of stability and robustness under perturbations, rooted in their special mathematical properties. Apriori, it is not always clear whether a given quantum state of matter is topological or not. We propose a mathematical criterion, which we call “the geometric test", to tell whether a state of matter is in a topological phase. We then apply our test to strongly-interacting states of matter in Quantum Hall effect, observed in certain 2d materials (Gallium-arsenide, graphene, ...) at low temperatures and in strong magnetic fields. I will explain the idea of the test (which works pretty well) and the results, based on recent work with Dimitri Zvonkine (CNRS, Versailles Mathematics Laboratory, Paris-Saclay University, France).


About the speaker:  Semyon Klevtsov obtained his PhD in 2009 at Rutgers University (USA), working on mathematical aspects of string theory. After a post-doctoral stays in Brussels and Cologne, he joined the Institute for Advanced Mathematical Research (IRMA) at the University of Strasbourg, as professor of mathematical physics. His most recent research is focused on mathematical aspects of the strongly correlated electron systems in condensed matter physics.

17/03/2022 - Vincent Loechner (ICube)  Modern Compiler Technology to Optimize Code from ODEs

Abstract: The MLIR compiler framework is a novel compiler infrastructure that eases the process of developing new interacting compiler passes, built on top of the LLVM compiler. According to, it especially "significantly reduces the cost of building domain specific compilers". I will shortly introduce MLIR and explain how to generate optimized compiled code using this framework.


Then, I will present our experience in the MICROCARD European project (, in collaboration with INRIA Bordeaux and KIT among other partners. Our aim is to write software to simulate cardiac electrophysiology using whole-heart models with sub-cellular resolution, on future exascale supercomputers. It builds on the existing open source openCARP project (, a cardiac electrophysiology simulator for in-silico experiments. OpenCARP includes a solver and the ionic model component describing ionic transmembrane currents, as ordinary differential equations (ODEs). They are provided using a DSL (domain specific language) for ODEs named easyML. The easyML input is analyzed and transformed into code by a python parser, which we modified to plug it to MLIR and generate OpenMP and vectorized efficient code. MLIR can also be used to generate GPU code, and we plan to experiment with this in the near future.

About the speaker: Vincent Loechner is assistant professor at University of Strasbourg in the computer science department, and the ICube Laboratory in the parallelism team (ICPS). He is also part of the INRIA CAMUS team. He is in charge of the compilation and code optimization work-package of the MICROCARD European project.

24/02/2022 - Jonathan Freundlich (ObAS)  Scaling relations as keys to unfold the complex physics of galaxies

Abstract: The physical processes driving galaxy formation and evolution span a vast range of scales, from the large scale structures of the universe to the turbulent interstellar medium and the interactions between light and matter. In this talk, I will present some of the empirical scaling relations that guide our understanding of these complex physical processes, focussing notably on the fate of gas within galaxies, star formation, and the relation between galaxies and their surrounding dark matter haloes.


About the speaker: Jonathan Freundlich did his Ph.D. between 2012 and 2015 at the Paris Observatory, probing star formation across cosmic time and modelling the influence of baryons on dark matter haloes. He was afterwards a postdoc at the Hebrew University of Jerusalem, where he gained experience in analysing cosmological simulations. He became Maître de Conférences at the Strasbourg Observatory in 2021, within the Galaxies, High Energy, Cosmology, Compact Objects & Stars (GALHECOS) research group.

20/01/2022 - Emmanuel Franck (IRMA)  Learning, geometry and PDEs, a promising interaction?

Abstract: In this talk, we want to introduce different examples or problems of interaction between deep learning, geometry, PDEs and numerical methods. We will start by illustrating the ability of deep learning to deal with physical problems starting from a classical problem in fluid mechanics: the closure. In a second step, we will introduce recent works mixing learning and differential geometry which allow to tackle unstructured data. We will illustrate this with simple examples from PDEs. Finally, we will show how ideas from analytical mechanics (and symplectic geometry) can interact with machine learning and numerical simulations of PDEs.

About the speaker: Emmanuel Franck did his Ph.D. thesis from 2009 to 2012 at the CEA on the numerical approximation of the radiative transfer equation. After that he did a 2 year post-doc at the Max Planck Institute for Plasma Physics in Munich on numerical methods for MHD in nuclear fusion. He is an INRIA young researcher since 2014 and his work focuses on the numerical approximation of PDEs in fluid mechanics and plasma physics. He is a member of the Modelling and Control (MOCO) research group at IRMA, Strasbourg. 

UFR de mathématique et d'informatique
Faculté de physique et ingénierie
Observatoire astronomique de Strasbourg