Riccardo Brasca
Riccardo Brasca is a mathematician who works on number theory and on formalizing mathematics in the Lean proof assistant, a field that AI tools are now entering. He completed a PhD at the Università degli Studi di Milano in 2012, held postdoctoral positions at ENS Lyon and the Max Planck Institute for Mathematics, and became a maître de conférences at Université Paris Cité in 2013. He began working in formalization in 2020, contributed to the Liquid Tensor Experiment, completed in 2022, and coordinated the Lean formalization of Fermat's Last Theorem for regular primes, with papers in 2023 and 2024. In 2026, he and Chris Birkbeck formalized Kummer's criterion for regularity using LLMs, and mathlib received the 2026 Demailly Prize. He is a maître de conférences at Université Paris Cité, a maintainer of mathlib and a scientific coordinator of the ANR project FALSE.
- Now at
- Université Paris Cité
- Works
- 14
- Citations
- 49
- h-index
- 4
Publication numbers from OpenAlex, as of 22 October 2026.
Timeline
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2012
A PhD in Milan
He completes his PhD in March 2012 at the Università degli Studi di Milano under Fabrizio Andreatta. His thesis concerns p-adic modular forms.
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Since 2013
Associate professor at Paris Cité
After postdoctoral positions at ENS Lyon, where Vincent Pilloni supervises him, and at the Max Planck Institute for Mathematics in Bonn, he becomes a maître de conférences (tenured associate professor) at Université Paris Cité in 2013. He is a member of the Institut de Mathématiques de Jussieu–Paris Rive Gauche.
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Since 2020
A mathlib maintainer
In 2020, he begins working in the formalization of mathematics. He serves as a maintainer of mathlib, the Lean mathematical library, whose maintainers hold the power to give final approval to proposed changes.
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2022
The Liquid Tensor Experiment
In July 2022, the Lean community completes the Liquid Tensor Experiment, a formal verification of the main theorem of liquid vector spaces posed as a challenge by Peter Scholze. He is among the contributors to the project, which Johan Commelin leads.
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2023–2024
Fermat's Last Theorem in Lean
He coordinates the Lean project to formalize Fermat's Last Theorem for regular primes. In 2023, he and three coauthors post a formalization of the first case in Lean and mathlib. In 2024, he and five coauthors post a complete formalization that includes a proof of Kummer's lemma.
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March 2026
Synthetic differential geometry in Lean
In March 2026, he and Gabriella Clemente post "Synthetic Differential Geometry in Lean" on arXiv. They formalize a Taylor theorem for functions of several variables in Lean and mathlib, and point to the possibility of using mathlib for constructive mathematics.
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2026
A Demailly Prize for mathlib
In 2026, mathlib, the Lean library he maintains, is awarded the Demailly Prize.
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As of October 2026
Kummer's criterion with LLMs
He is a maître de conférences at Université Paris Cité whose research covers number theory and the formalization of mathematics, and a scientific coordinator of the ANR project FALSE. In May 2026, he gives a Colloquia Patavina talk in Padua, "Around Formalization: Why and How to Explain Mathematics to a Computer", that also covers how AI is beginning to transform formalization. In June 2026, he and Chris Birkbeck formalize Kummer's criterion for regularity, using LLMs.
Career
- Since 2013Université Paris CitéMaître de conférences
- 2015–2026Université Paris 8
- 2012–2013École Normale Supérieure de LyonPostdoctoral Researcher
- Max Planck SocietyPostdoctoral Researcher
Education
- 2012University of MilanPhD
Most-cited works
- p -adic modular forms of non-integral weight over Shimura curves
- Eigenvarieties for Cuspforms Over PEL Type Shimura Varieties With Dense Ordinary Locus
- Hida theory over some unitary Shimura varieties without ordinary locus
- Eigenvarieties for non-cuspidal modular forms over certain PEL Shimura varieties
- A complete formalization of Fermat's Last Theorem for regular primes in Lean
Sources and credits
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- Riccardo Brasca
- Progrès récents dans la formalisation de la théorie des nombres | Collège de France
- Colloquia Patavina for Students: Around Formalization: Why and How to Explain Mathematics to a Computer
- Mathlib maintainers | Lean Community
- Completion of the Liquid Tensor Experiment | Lean community blog
- [2305.08955] Fermat's Last Theorem for regular primes
- [2410.01466] A complete formalization of Fermat's Last Theorem for regular primes in Lean
- [2603.17457] Synthetic Differential Geometry in Lean

