Journées annuelles de la fédération occimath

Liste des Contributions

1. Energy-consistent modeling and simulation of stents in arterial tissues

Francesco BONALDI

27/05/2026 14:00

In this talk, we focus on the modeling and simulation of large-strain (hyperelastic) elasticity problems, with particular application to the study of soft biological tissues. We also consider frictional contact between two hyperelastic bodies, with application to the deployment of a stent in an arterial tissue. For the numerical approximation, the key idea is to design a time integration...

2. Événements exceptionnels en géométrie aléatoire convexe

Pierre CALKA

27/05/2026 15:00

Dans cet exposé, nous construisons des objets géométriques aléatoires à partir de la donnée d'un processus ponctuel de Poisson dans l'espace euclidien et cherchons à estimer la probabilité d'événements rares, c'est-à-dire de configurations géométriques exceptionnelles. Nous décrivons trois exemples : tout d'abord, nous générons une partition aléatoires de l'espace en polyèdres convexes, dite...

3. A mathematician's view on symmetries of quantum fields

David JORDAN

27/05/2026 16:30

The past four decades have witnessed a vibrant and profound dialog between mathematics and quantum physics. The fundamental driving challenge here is how to reconcile the rigid algebraic structures of quantum physics with the geometric fluidity of relativistic spacetime. It turns out that such questions, and their as yet woefully incomplete answers, are as illuminating within pure...

4. Spectral diagonalization in high dimensions and its implications for learning dynamics

Bilel BENSAID

28/05/2026 09:00

We study the spectral structure of Gram matrices arising in high-dimensional learning problems and its implications for optimization dynamics. First, we prove that for independent, centered, anisotropic vectors, the normalized Gram matrix converges to the identity in operator norm, under mild assumptions on intrinsic dimension and tail behavior. This extends classical isotropic results to a...

5. Geometric properties of optimizers for the maximum gradient of the torsion function via probabilistic approaches

Ilias FTOUHI

28/05/2026 09:50

We consider the shape optimization problem of looking for the shape that maximizes the maximal norm of the gradient of the torsion function among planar convex sets with a prescribed measure (or perimeter). We prove the existence of such a shape and prove that its boundary is C^1 regular. Then, we show that its boundary contains a segment. The proofs are mainly based on probabilistic arguments...

6. Un tour d’horizon des résultats récents sur les algorithmes inertiels dans un cadre déterministe

Aude RONDEPIERRE

28/05/2026 11:00

7. Cross-Modality Alignment for Integration of Spatial Omics Data

Benjamin CHARLIER

28/05/2026 14:00

Abstract: Advances in spatial omics sequencing now enable acquisition of massive subcellular-scale datasets (millions of reads with hundreds of detectable genes). However, heterogeneity in measured features, spatial resolution, and physical sampling scope across technologies and experimental protocols introduces significant challenges for integrating these datasets within reference coordinate...

8. Optimizing prior knowledge integration in regression-based gene network inference

Sophie LEBRE

28/05/2026 14:50

The growing availability of diverse omics datasets motivates integrative approaches for gene regulatory network inference.
Regression-based methods for gene regulatory network inference (Inferelator, GENIE3, DynGENIE3, IRafNet) identify key regulators and can incorporate prior knowledge to guide variable selection.
We propose a method to tune the strength of prior knowledge integration in...

9. Time series forecasting with hybrid physics-data models: application to lake thermal stratification

David METIVIER

28/05/2026 16:00

Forecasting the future state of a dynamical system from observed time series is a central problem across science and engineering.
Classical autoregressive models offer simplicity and interpretability but struggle with complex nonlinear dynamics.
Deep learning architectures such as Recurrent Neural Networks overcome this limitation yet offer no physical guarantees, leading to unphysical...

10. Extreme value inference for heterogeneous heavy-tailed data: A derandomization theory

Joseph Hachem (Toulouse School of Economics)

29/05/2026 09:00

When assessing extreme risks, several risk measures depend on extreme value parameters that can be estimated via empirical mean excesses. A key mathematical challenge in studying these estimators is their reliance on high-order statistics above a random threshold. In this talk, we use simple yet novel derandomization arguments to derive the joint asymptotic distribution of these tail empirical...

11. Efficient estimation of Sobol' indices of any order from a single input/output sample

Agnès LAGNOUX

29/05/2026 09:50

12. An alternative ranking system for biathlon pursuit races

Rémi SERVIEN

29/05/2026 11:00

Biathlon is an Olympic sport combining cross-country skiing with rifle shooting, giving a penalty for each target miss. The biathletes ran different race formats, including the pursuit race. During this race, the biathletes chase the leader with a start time identical to the result of the sprint race previously achieved. So, pursuit involves different skills (such as tactics or management of...