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Pierre-Cyril Aubin-Frankowski

Researcher/Associate professor in Optimization and Machine learning

CERMICS, ENPC, IPP

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Biography

I am an associate professor at Ecole des Ponts ParisTech and a researcher at CERMICS, in the Optimization team. I am interested in the relations between optimization algorithms in finite and infinite dimensions, their convergence properties and the associated notions of convexity. My main playfield is optimization in the space of probability measures, in connection with optimal transport theory and optimal control. We develop applications of these methods with Axel Parmentier for operations research, working in particular with Air France.

My latest focus is on optimization problems where the notion of distance is replaced by a generic cost function (slides), e.g., Bregman divergences. The natural algorithm here is alternating minimization (article) and the convergence assumptions and limit flow are related to Evolution Variational Inequalities (article). I also work on the characterization of order isomorphisms with Stéphane Gaubert (article and slides). Both directions unite in article on novel inf-representations for entropic optimal transport.

I was a post-doctoral researcher in 2023-24 at TU Wien VADOR with Aris Daniilidis; in 2021-23 at INRIA SIERRA, with Alessandro Rudi. I obtained my PhD in July 2021 from École des Mines Paris – PSL (Paris), at the CAS laboratory, working on shape/state constraints in optimal control and nonparametric regression through kernel methods (manuscript, slides). I graduated from École polytechnique (X2013) in 2017, then obtained my Master degree (MVA, Mathematics-Vision-Learning) with Highest Honours after an internship on gene network inference (based on single-cell RNA sequencing).

Follow-ups on my PhD tackle the links between kernel methods, optimal control, Kalman filtering and optimization in measure spaces. So far I have shown that kernels appear in linear-quadratic optimal control because of Hilbertian vector spaces of trajectories, while, for estimation problems, they appear through covariances of Gaussian processes. It is this dual, deterministic and stochastic, nature of kernels which underlies the duality between optimal control and estimation in the Linear-Quadratic case (see arXiv, slides with Alain Bensoussan). Kernels even extend to mean-field control (article).

  • If you want an overview of some of my research up to July 2023 concerning optimization and kernels, here are some (slides).

  • If you want an overview of some of my research up to November 2025 concerning gradient flows with general costs, here is a video.

My research and my lyricomania, a passion I share within the association Juvenilia, do not leave me so much time to spare, but I occasionnaly paint.

Contact: pierre-cyril[dot]aubin(at)enpc[dot]fr

Interests

  • Optimization with general costs
  • Flows on measure spaces
  • Kernel Methods
  • Optimal Control

Education

  • Postdoc in Optimization, 2023-2024

    TU Wien

  • Postdoc in Machine Learning, 2021-2023

    INRIA Paris

  • PhD in Machine Learning & Control Theory, 2018-2021

    MINES ParisTech

  • MS (M2) in Machine Learning, 2016-2017

    ENS Paris-Saclay

  • MS (M1) in Applied Maths, 2013-2016

    École polytechnique

Publications

  1. (submitted) PCAF, Virginie Ehrlacher, Gabriele Todeschi, Debiasing optimal transport: classical and entropic, April 2026, arXiv

  2. PCAF, Giacomo Enrico Sodini, Ulisse Stefanelli, Evolution variational inequalities with general costs, May 2025, Journal of Function Analysis, arXiv, article, slides

  3. Clément Bonet, Théo Uscidda, Adam David, PCAF, Anna Korba, Mirror and Preconditioned Gradient Descent in Wasserstein Space, June 2024, NeurIPS 2024 (spotlight), arXiv, article, slides (long)

  4. (submitted) PCAF, Yohann de Castro, Axel Parmentier, Alessandro Rudi, Generalization Bounds of Surrogate Policies for Combinatorial Optimization Problems, July 2024, arXiv, slides

  5. PCAF, Alain Bensoussan, Reproducing Kernel Approach to Linear-Quadratic Mean Field Control Problems with Additive Noise, July 2024, article, CDC 2024

  6. PCAF, Stéphane Gaubert, Order isomorphisms of sup-stable function spaces: continuous, Lipschitz, c-convex, and beyond, April 2024, Communications in Contemporary Mathematics, arXiv, articleslides

  7. (submitted) PCAF, Alain Bensoussan, Reproducing kernel approach to linear quadratic mean field control problems, August 2023, arXiv

  8. PCAF, Alain Bensoussan, S. Joe Qin, Alternating minimization for simultaneous estimation of a latent variable and identification of a linear continuous-time dynamic system, August 2023, Communications in Optimization Theory, arXiv, article

  9. (submitted) Flavien Léger, PCAF, Gradient descent with a general cost, May 2023, arXiv, slides

  10. PCAF, Alessandro Rudi, Approximation of optimization problems with constraints through kernel Sum-Of-Squares, Optimization, February 2024, article, arXiv, slides

  11. PCAF, Stéphane Gaubert, Tropical reproducing kernels and optimization, Integral Equations and Operator Theory, December 2022, article, arXiv, slides

  12. PCAF and Zoltán Szabó, Handling Hard Affine SDP Shape Constraints in RKHSs, November 2022, JMLR, article, arXiv, HAL, code

  13. PCAF, Alain Bensoussan, The reproducing kernel Hilbert spaces underlying linear SDE Estimation, Kalman filtering and their relation to optimal control, August 2022, Pure and Applied Functional Analysis, arXiv, slides

  14. PCAF, Anna Korba, Flavien Léger, Mirror Descent with Relative Smoothness in Measure Spaces, with application to Sinkhorn and EM, December 2022, NeurIPS 2022, arXiv, slides (short), slides (long), poster

  15. PCAF, Alain Bensoussan, Operator-valued Kernels and Control of Infinite dimensional Dynamic Systems, June 2022, CDC 2022, article, arXiv, slides

  16. PCAF, Stability of solutions for controlled nonlinear systems under perturbation of state constraints, June 2022, IFAC CAO 2022, article, arXiv, slides

  17. Anna Korba, PCAF, Szymon Majewski and Pierre Ablin, Kernel Stein Discrepancy Descent, ICML 2021 (long oral), July 2021, article, arXiv, code/website, pdf, slides, poster

  18. PCAF, Linearly-constrained Linear Quadratic Regulator from the viewpoint of kernel methods, SIAM Journal on Control and Optimization, February 2021, article, arXiv, HAL, pdf, code, slides

  19. PCAF, Interpreting the dual Riccati equation through the LQ reproducing kernel, Comptes Rendus - Mathématique, January 2021, article, arXiv, HAL, pdf, slides

  20. PCAF and Zoltán Szabó, Hard Shape-Constrained Kernel Machines, NeurIPS 2020, December 2020, article, arXiv, HAL, pdf, code

  21. PCAF, Nicolas Petit and Zoltán Szabó, Kernel Regression for Trajectory Reconstruction of Vehicles under Speed and Inter-Vehicular Distance Constraints, Proceedings IFAC WC 2020, July 2020, article, pdf, slides, video

  22. PCAF and Jean-Philippe Vert, Gene regulation inference from single-cell RNA-seq data with linear differential equations and velocity inference, Bioinformatics, June 2020, article, biorXiv, pdf, supp, code

  23. PCAF and Nicolas Petit, Data-driven approximation of differential inclusions and application to detection of transportation modes, Proceedings ECC 2020, May 2020, article, pdf, slides, video

  24. PCAF, Lipschitz regularity of the minimum time function of differential inclusions with state constraints, Systems & Control Letters, April 2020, article, pdf

Recent & Upcoming

 
 
 
 
 

Jan 2025 – Present
  • Gilles Févry start his internship on diffusion models in combinatorial optimization at CERMICS in May!
  • Clotilde Cantini start her internship on revenue management for Air France at CERMICS in May!
  • Talk at Séminaire du CMAP, Saclay, April
  • Invited talk at Journées SMAI MODE 2026 in Nice, March
  • Attended CJC-CMA 2026, ENPC, March
  • Talk at PDE afternoon in Vienna, January
  • Teaching assistant on Convex Optimization at ENPC Feb-June
  • Lecturing course on Decision in Uncertainty (Markov chains, Bellman equations) at ENPC Feb-March
 
 
 
 
 

Jan 2025 – Dec 2025
 
 
 
 
 

Jan 2024 – Dec 2024
 
 
 
 
 

Jan 2023 – Dec 2023
 
 
 
 
 

Jan 2022 – Dec 2022
  • Talk in invited session at CDC22 on LQ kernel for PDE control, December
  • Talk in invited session at NeurIPS22 on mirror descent in measure spaces, December
  • Talk in invited session at MTNS22 on stability of trajectories under constraint perturbation, September
  • Talk in invited session at ORCOS-VC22 on LQ kernel for state constraints, July
  • Talk in invited session at IFAC-CAO on stability of trajectories under constraint perturbation, July
  • Talk in invited session at EURO22 on handling with kernels infinitely many constraints through a finite number, July
  • Talk in invited session at FGP2022, May
  • Talk at Séminaire Parisien d’Optimisation, February
  • Talk at GdT Contrôle on LQ kernel for state constraints, January
  • Award of best post-doc presentation at Lifting Inference with Kernel Embeddings LIKE22 Bern, January
 
 
 
 
 

Jan 2021 – Dec 2021
 
 
 
 
 

Jan 2020 – Dec 2020