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Séminaire des Doctorantes et Doctorants du laboratoire J. A. Dieudonné

Organizers/Organisateurs :  Cassandre Trioux (cassandre.trioux at univ-cotedazur.fr) Anton Baeza (anton.baeza at univ-cotedazur.fr)
 

--- English Version ---

The Doctoral Seminar will take place this year once or twice a month between October 2025 and June 2026. It is aimed at all young members of the laboratory, as well as motivated M2 students. This seminar consists of a 50 min presentation related to his research, then 10 min of questions.

  • To attend : the schedule of upcoming presentations is below and many email reminders will be sent.

  • To exhibit : please contact Cassandre or Anton. As the public comes from various horizons of mathematics, an effort must be made to make the presentation as accessible as possible. The presentations are validated and counted as training hours by the EDSFA.

 

--- French Version ---

Le séminaire des Doctorants aura lieu cette année une ou deux fois par mois entre Septembre 2025 et Juin 2026. Il s'adresse à tous les jeunes membres du laboratoire, ainsi qu'aux étudiants de M2 motivés. Ce séminaire consiste en une présentation de 50 min en lien avec sa recherche, puis de 10 min de questions.

  • Pour assister : le calendrier des exposés à venir est ci-dessous et de nombreux rappels par mails seront effectués.

  • Pour exposer : veuillez contacter Cassandre ou Anton. Comme le public vient d'horizons divers des mathématiques, il faut faire un effort pour que l'exposé soit le plus accessible possible. Les présentations sont validées et comptées comme heures de formation par l'EDSFA.

 

Calendar of upcoming talks / Calendrier des prochains exposés : 

DateHours/HeureRoom/SalleSpeaker/OrateurTitle/Titre
17 April 202610:30AMSalle de conférencesGregorio RebecchiEstimation of Synaptic connectivity in brain organoids
January 2026TBATBALuis BottraudTBA

 

 

 

 

 

 

 

Past talks / Exposés passés (2023/2025) :

DateHours/HeureRoom/SalleSpeaker/OrateurTitle/Titre
31 March 20262:00PMSalle de conférencesAugustin PuelDrift Estimation for N Particle Mean-Field Models with Fractional Noise under Discrete Observations
Abstract : The parametric estimation of mean field models driven by Brownian motion has been widely studied in recent years. In this vein, we extend this study to models driven by fractional Brownian motion. In this presentation we will introduce a new estimator of the drift parameter based on discrete observations of an N particles mean field model with additive noise driven by a fractional Brownian motion. Because the process lacks both martingale and Markov properties, our analysis relies on pathwise arguments. We investigate the asymptotic properties of the model and of the estimator in for the Hurst parameter H>1/3. Moreover, we explain how to jointly estimate the diffusion coefficient and the Hurst parameter along with the drift.
16 March 20262:00PMSalle 1Fabrizio CurtoRationality Problems in Algebraic Geometry
Wednesday 4 march 20262:00PMSalle de conférencesLiqingjing WangDeformation of canonical line bundle in smooth Kähler family
Monday 9 February 20263:30 PMSalle de séminaireAntoine Dolozilek FillaireInvariant geometric structures
Thursday 29 January 20262:00 PMSalle réunion FizeauThomas JacuminCompression d'image par EDP
December 10th 202510:30 AMSalle de conférencesClément MariotSearching for Keplerian turbulence using optimal control
Samuel GallayRegularization by noise with fractional Brownian motion
Abstract : The non-linear stability and possible route to hydrodynamic turbulence in Keplerian flows remains an open question, with implications for the transport of angular momentum in cold accretion disks. We propose to use adjoint based optimal control to track pertubations yielding subcritical transitions in such flows. To that end we have developed a numerical framework based on Tchebycube, a new HPC spectral solver, handling both the direct and adjoint problems. This approach identifies initial conditions that locally extremize a quantity of interest (a marker of turbulence), potentially revealing transition-prone structures and amplification mechanisms.
Abstract : When an ordinary differential equation is ill-posed, meaning that it has no or multiple solutions, it may happen that adding a (small) noise term to the equation restores its well-posedness. That is the phenomenon that we call regularization by noise, and that we will discuss in this short talk. As the noises we are considering are not necessarily Markovian, the proofs are not using tools from stochastic calculus, and you won't even need to know the Itô formula to follow this talk. This work was done in collaboration with Oleg Butkovsky (WIAS Berlin).

More precisely, we study a multidimensional stochastic differential equation with additive noise:
dXt = b(t, Xt)dt + dξt,
where the drift b is integrable in space and time, and ξ is either a fractional Brownian motion or an α-stable process. We show weak existence of solutions to this equation under the optimal condition on the integrability indices of b, going beyond the subcritical Krylov-Röckner (Prodi-Serrin-Ladyzhenskaya) regime. This extends the recent results of Krylov (2020) to the fractional Brownian and Lévy cases. We also construct a counterexample to demonstrate the optimality of this condition. Our methods are built upon a version of the stochastic sewing lemma of Lê and the John–Nirenberg inequality.
November 26th 202510:30 AMSalle réunion FizeauLorenzo PoggioniA new class of finite difference methods : the zigzag schemes
November 12th 202510:30 AMSalle de conférenceMeriem BahhiEtude mathématique d'une équation quasi-linéaire de type Schrödinger
November 5th 202510:30AMSalle de conférencesLucas BabetRandom matrices and graph limits
October 15th 202511:00 AMSalle réunion FizeauSebastian BaudeletRate of chaos propagation of the stochastic coalescence process
 
2023-2024
 
June 26th 20242:00PMRoom 2Thomas BouchetCourbes de genre 4 : invariants et reconstruction
June 2024  Antoine CommaretHomological persistence.
April 2024  Sophie JaffardSpiking Neural Networks : learning as Hawkes processes
March 2024  Bruno DewerApparences of the Farey sequence in Algebra and Geometry
January 2024  Alex MorianiGlobal Geometry in nonpositive curvature
December 2023  Meriem BahhiA mathematical study of a quasi linear Schrodinger-type equation
December 2023  Zakaria OuarasModuli space of vector bundles