News

HOL-CSP: A Comprehensive Process Theory for Semantics and Proc-Omata Reasoning

Dec 18 14:00 ₂₀₂₅

Abstract: CSP (Concurrent Sequential Processes) is a theory for concurrent computations and interaction. HOL-CSP is a conservative embedding of CSP into Higher-order logic (HOL); this gives rise to an environment that allows formal, machine-assisted proof of behaviour which is rich in data. A particular class of processes can be seen as symbolic automata whose finite instances can be treated by a model-checker. HOL-CSP is very

expressive and allows for representing finite automata and their infinite extensions as occurring for dense time, physical systems, and parameterized process architectures. Read more...

Precise and Efficient Memory Analysis of Low-level Languages

Dec 17 14:00 ₂₀₂₅

Wednesday 17 December 2025 at 14h00
ENS Paris-Saclay, Room 1Z61 and online

Abstract: Memory safety is crucial for systems like embedded software and operating systems, where errors such as buffer overflows or use-after-free can lead to serious security issues. This thesis presents a sound, automated, and practical static analysis to prove spatial memory safety in binary code or C programs. The method builds on a novel dependent type system called TypedC which extends C's types to express complex memory properties. It works without modifying source code and uses abstract interpretation to check types and ensure spatial memory safety. A second contribution is a new framework for building relational compositional abstract domains called AADT. It enables precise analysis of complex data types like arrays, structs, and unions. The approach is implemented in the Codex platform and tested on real-world low-level code, showing strong results in verifying memory safety. Read more...

Contributions to FHE security against CCA adversaries

Dec 10 14:00 ₂₀₂₅

Wednesday 10 December 2025 at 14h00
CEA Nano-Innov (Building 862, Amphi 33-34) and online

Abstract: Homomorphic encryption (FHE) is a cryptographic tool allowing the delegation of computations over sensitive data while preserving its confidentiality. Unfortunately, what makes the power of FHE, its malleability (the ability to perform computations over ciphertexts), is also one weak point. On their own, homomorphic schemes only provide a relatively low security guarantee (CPA security, which models passsive adversaries) in comparison to what is usually expected (CCA2 security, which models active adversaries) from more "classical" cryptosystems. Read more...

Permutation equivariant and permutation invariant reinforcement learning for multi-agent systems

Dec 11 9:00 ₂₀₂₅

Thursday 11 December 2025 at 9h00
ENS Paris-Saclay, Room 1Z25 and online

Abstract: Deep Reinforcement Learning (DRL) has achieved remarkable success in sequential decision-making tasks, from games to robotics. Extending DRL to Multi-Agent Reinforcement Learning (MARL) introduces additional challenges: agents must coordinate in high-dimensional environments, training becomes unstable due to non-stationarity, and learned strategies often fail to generalize across team sizes or tasks.

Read more...

Causal graph rewriting: Space-time determinism and reversibility

Dec 2 10:30 ₂₀₂₅

Tuesday 2 December 2025 at 10h30
Amphi building 660 and online

Abstract: We study non-terminating graph rewriting models, whose local rules are applied non-deterministically---and yet enjoy a strong form of determinism, namely space-time determinism. For terminating computation, it is well-known that the property of confluence may ensure a deterministic end result. In the context of distributed, non-terminating computation however, confluence alone is too weak a property. In this thesis we provide sufficient conditions so that asynchronous local rule applications produce well-determined events in the space-time unfolding of the graph, regardless of their application orders.

Read more...

Programming language and formally verified compiler for low-level numerical libraries

Nov 25 14:00 ₂₀₂₅

Tuesday 25 November 2025 at 14h00
ENS Paris-Saclay, Room 1Z76 and online

Abstract: Low-level numerical libraries like GMP and BLAS are widely used. They are mostly written in C, Fortran, and Assembly, and make a heavy use of arrays and pointers. These languages are well-suited for writing efficient code but they are not safe, that is, they have many undefined behaviors, which increase the chance for bugs. Read more...

The CNRS blog Focus Sciences recently published an article, “The art of modelling complex computing systems”, featuring the work of the ANR project NARCO (Non-Aggregative Resource COmpositions). The project explores new logic-based methods to model and verify complex computing systems by capturing the real interactions—sharing, dependencies and coordination—between their components. At LMF, Mihaela Sighireanu leads the lab’s contribution, focusing on verification techniques grounded in extended separation logics. This approach promises more expressive yet automatable analyses of evolving systems. Learn more on the project presentation and discover its partners: LIG, VERIMAG and LORIA.

Le blog Focus Sciences du CNRS consacre un article, « L’art de modéliser des systèmes informatiques complexes », au projet ANR NARCO (Non-Aggregative Resource COmpositions). Ce projet développe de nouvelles approches logiques pour modéliser et vérifier des systèmes informatiques complexes, en tenant compte des interactions réelles entre leurs composants : partage, dépendances et coordination. Au LMF, Mihaela Sighireanu pilote la contribution du laboratoire, centrée sur des techniques de vérification fondées sur des logiques de séparation étendues. Cette approche vise une analyse à la fois plus expressive et plus automatisable des systèmes en évolution. Pour en savoir plus, consultez la présentation du projet et les sites de ses partenaires : LIG, VERIMAG et LORIA.

Raghda El Shehaby (TU Wien, Institute of Computer Engineering), Matthias Függer (LMF, CNRS, ENS Paris-Saclay), Florian Huemer (TU Wien, Institute of Computer Engineering) and Andreas Steininger (TU Wien, Institute of Computer Engineering) received the Best IEEE ASYNC Paper Award in 2025. Read more...

C'est avec une immense tristesse que nous avons appris le décès de notre collègue Gilles Dowek, survenu le 21 juillet 2025.

Directeur de recherche chez Inria, professeur attaché à l’ENS Paris-Saclay, fondateur de l’équipe Deducteam et membre du Laboratoire Méthodes Formelles, Gilles Dowek a contribué de manière exceptionnelle à l'essor scientifique de la discipline informatique. Read more...

Mickaël Laurent, ancien doctorant du LMF et de l'IRIF, encadré par Giuseppe Castagna et Kim Nguyễn, a reçu le prix de thèse du GdR Génie de la Programmation et du Logiciel, décerné le 19 juin lors des journées nationales du GdR.

Sa thèse est intitulée Inférence de types polymorphes pour des langages dynamiques : reconstruction de types pour des systèmes combinant polymorphisme paramétrique, surcharge et sous-typage”. Félicitations à Mickaël pour son excellent travail !

(photo avec l'autorisation des personnes, de gauche à droite Anouck Chan, première accessit, Pascal Poizat, co-président du jury et Mickaël)

Plus d'informations sur le site du GdR.

A New Scientist column  entitled "Where does time actually come from?" discusses the recent contribution by Pablo Arrighi and Gilles Dowek from LMF and Amélia Durbec from IEMN, to the somewhat fundamental questions about the nature of Time.

Read more...