Gaëtan Serré

Centre Borelli
ENS Paris-Saclay

Gaëtan Serré

PhD candidate in mathematics

About

I am a PhD student in mathematics at Centre Borelli — École Normale Supérieure Paris-Saclay since 2023, under the supervision of Nicolas Vayatis and Argyris Kalogeratos.

Currently, I am building a framework in where a probabilistic program is written once, then both executed as a sampler and interpreted as a probability measure, so that theorems can be proved about it. I am also interested in the study of global optimization algorithms, especially those modeled as systems of stochastic differential equations. I contribute to and to Mathlib, its community-driven library of formalized mathematics.

You can find details on my academic background in my CV.

Gaëtan Serré giving a talk
Budding Maths Institut des Hautes Études Scientifiques (IHES), France

Contact

GitHub
@gaetanserre
The curved metal facade of Dongdaemun Design Plaza
Dongdaemun Design Plaza Seoul, South Korea

Publications

For a complete list of my publications, please visit my Google Scholar profile.

  1. arXiv2026

    Enhancing Exploration in Global Optimization by Noise Injection in the Probability Measures Space

    Gaëtan Serré, Pierre Germain, Samuel Gruffaz & Argyris Kalogeratos

    arXiv

    McKean-Vlasov (MKV) systems provide a unifying framework for recent state-of-the-art particle-based methods for global optimization. While individual particles follow stochastic trajectories, the probability law evolves deterministically in the mean-field limit, potentially limiting exploration in multimodal landscapes. We introduce two principled approaches to inject noise directly into the probability law dynamics: a perturbative method based on conditional MKV theory, and a geometric approach leveraging tangent space structure. While these approaches are of independent interest, the aim of this work is to apply them to global optimization. Our framework applies generically to any method that can be formulated as a MKV system. Extensive experiments on multimodal objective functions demonstrate that both our noise injection strategies enhance consistently the exploration and convergence across different configurations of dynamics, such as Langevin, Consensus-Based Optimization, and Stein Boltzmann Sampling, providing a versatile toolkit for global optimization.

  2. arXiv2025

    A Unifying Framework for Global Optimization: From Theory to Formalization

    Gaëtan Serré, Argyris Kalogeratos & Nicolas Vayatis

    arXiv

    We introduce an abstract measure‑theoretic framework that serves as a tool to rigorously study stochastic iterative global optimization algorithms as a unified class. The framework is formulated in terms of probability kernels, which, via the Ionescu–Tulcea theorem, induce probability measures on the space of sequences of algorithm iterations, endowed with two intuitive properties. This framework answers the need for a general, implementation‑independent formalism in the analysis of such algorithms, providing a starting point for formalizing global optimization results in proof-assistants. To illustrate the relevance of our tool, we show that common algorithms fit naturally in the framework, and we also use it to give a rigorous proof of a general consistency theorem for stochastic iterative global optimization algorithms (Proposition 3 of [1]). This proof and the entire framework are formalized in the proof assistant. This formalization both ensures the correctness of the definitions and proofs, and provides a basis for future machine-assisted formalizations in the field.

  3. AISTATS2025

    Stein Boltzmann Sampling: A Variational Approach for Global Optimization

    Gaëtan Serré, Argyris Kalogeratos & Nicolas Vayatis

    AISTATS

    In this paper, we present a deterministic particle-based method for global optimization of continuous Sobolev functions, called Stein Boltzmann Sampling (SBS). SBS initializes uniformly a number of particles representing candidate solutions, then uses the Stein Variational Gradient Descent (SVGD) algorithm to sequentially and deterministically move those particles in order to approximate a target distribution whose mass is concentrated around promising areas of the domain of the optimized function. The target is chosen to be a properly parametrized Boltzmann distribution. For the purpose of global optimization, we adapt the generic SVGD theoretical framework allowing to address more general target distributions over a compact subset of Rd, and we prove SBS’s asymptotic convergence. In addition to the main SBS algorithm, we present two variants: the SBS-PF that includes a particle filtering strategy, and the SBS-HYBRID one that uses SBS or SBS-PF as a continuation after other particle- or distribution-based optimization methods. A detailed comparison with state-of-the-art methods on benchmark functions demonstrates that SBS and its variants are highly competitive, while the combination of the two variants provides the best trade-off between accuracy and computational cost.

  4. SETN2024

    LIPO+: Frugal Global Optimization for Lipschitz Functions

    Gaëtan Serré, Perceval Beja-Battais, Sophia Chirrane, Argyris Kalogeratos & Nicolas Vayatis

    SETN

    In this paper, we propose simple yet effective empirical improvements to the algorithms of the LIPO family, introduced in [1], that we call LIPO+ and AdaLIPO+. We compare our methods to the vanilla versions of the algorithms over standard benchmark functions and show that they converge significantly faster. Finally, we show that the LIPO family is very prone to the curse of dimensionality and tends quickly to Pure Random Search when the dimension increases. We give a proof for this, which is also formalized in the programming language. Source codes and a demo are provided online.

Projects

Here is a non-exhaustive list of personal projects I have worked on.

· Mathlib

Kernel-Hom

A library that provides tactics to simplify kernel equalities by leveraging categorical reasoning. It automatically translates kernel equalities into equalities in a monoidal category, where powerful tactics from the category theory part of Mathlib can be applied. This project lead to several PRs (#36779; #38211; #38212; #37851) in Mathlib.

Python · C++

GLOBe

GLOBe (Global Optimization Benchmark) is a Python package to benchmark global optimization algorithms over a wide range of test functions. It includes C++ implementations of many algorithms as well as various benchmark functions.

· Formalization

LipoCons

LipoCons is the formalization of the abstract definition of global optimization algorithms presented in [1]. It also includes the formalization of the equivalence between consistency and sampling the whole search space, a proposition introduced in [2].

Worst-case analysis

GPEP

GPEP (Generalized Performance Estimation Problems) is a computer-assisted worst-case analyses of first-order optimization methods. It uses symbolic computation to automatically derive worst-case guarantees for any deterministic first-order method on various classes of functions.

A person in a red coat walking on a wet beach at dusk
Cabourg France · 49°17'38.8"N 0°07'05.7"W

Talks

  1. 2026

    Institut des Hautes Études Scientifiques

    Budding Maths slides

  2. 2025

    AISTATS

    Stein Boltzmann Sampling

  3. 2024

    Collège de France

    1st prize challenge Accenta

  4. 2022

    NeurIPS

    AutoML Decathlon

  5. 2022

    IEEE WCCI IJCNN

    L2RPN competition

Teaching

  • Introduction to Statistical Learning

    M.Sc. Mathématique, Vision, Apprentissage

  • Analyse & Convergence

    Double B.Sc. Computer Science & Mathematics

  • Préparation oraux X (Math380X)

    Double B.Sc. Mathematics

  • Inférence Statistique

    Double B.Sc. Computer Science & Mathematics

A large red playground structure with slides under a pale sky
Near Simose Art Museum Hiroshima, Japan · 34°14'22.8"N 132°13'36.6"E

Internships

  1. 2023

    Centre Borelli — École Normale Supérieure Paris-Saclay

    Pre-PhD on stochastic global optimization and sampling methods

  2. 2021

    Laboratoire Méthodes Formelles

    Deductive program checking using Why3

Education

  1. 2022— 2023

    Centre Borelli — École Normale Supérieure Paris-Saclay

    M.Sc. Mathématiques, Vision, Apprentissage

  2. 2021— 2022

    Université Paris-Saclay

    M.Sc. Artificial Intelligence

  3. 2018— 2021

    Université Paris-Saclay

    Double B.Sc. Mathematics & Computer Science

Miscellaneous

Website
This website is inspired by the sites of Justin Asher and NYC Lean. The cross-stitched name is a nod to the poster of the exhibition Extraordinary — 시간이 쌓이는 순간 (Seoul Museum, 2026), and the color palette, the buttons and the needle to Henry Selick's Coraline (2009). The previous design was largely inspired by Chloé Antoine's.
Handy tools
Typst: a modern LaTeX alternative; Lazygit: a simple terminal UI for git
Play & learn
Game Server: games to learn about and its mathematical library; Learn Git Branching: an interactive way to learn git
Non-academic interests
I enjoy travel photography (you can find some on this site), cataloging and commenting on films, TV shows and video games on SensCritique, collecting audio equipment (currently on repeat: Dire Straits, Telegraph Road), and cheering for my favorite LoL esports team.
A field at sunset, lined with birch trees and a stone wall
Biollet France · 46°00'08.3"N 2°42'28.7"E