The Laboratoire Méthodes Formelles (LMF) was founded on 1 January 2021 as a joint research centre of University Paris-Saclay, CNRS, ENS Paris-Saclay, Inria, and CentraleSupélec with a main focus on formal methods. The new laboratory combines the expertise of about 100 members from the former Laboratoire Spécification et Vérification (LSV) and the VALS team of Laboratoire de Recherche en Informatique (LRI).

In our mission to enlighten the digital world through Mathematical Logic, we rely on formal methods as a tool to analyse, model, and reason about computing systems, such as computer programs, security protocols, and hardware designs. Our research targets a wide range of computational paradigms, from classical to emerging ones such as biological and quantum computing.

LMF is structured around three hubs: Proofs and Models, which lie at the heart of our historical background, and Interactions, that is aimed at fostering cross-fertilisation between formal methods and other domains in computing science and beyond.

Patricia Bouyer (LMF, CNRS), B Srivathsan (CMI and ReLaX, India) and Vaishnavi Vishwanath (CMI, India) received the Best ETAPS Paper Award in 2025, which is given to the best theoretical paper at ETAPS, the International Joint Conferences on Theory and Practice of Software. Read more...

Learn Programming with OCaml is a new book by Sylvain Conchon and Jean-Christophe Filliâtre. This is an English translation (by Urmila Nair) of the French edition Apprendre à programmer avec OCaml.

The book is available as a PDF file, under the CC-BY-SA license. The source code for the various programs contained in the book is available for download, under the same license.

The book is structured in two parts. The first part is a tutorial-like introduction to OCaml through 14 small programs, covering many aspects of the language. The second part focuses on fundamental algorithmic concepts, with data structures and algorithms implemented in OCaml.

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.

Since the laws of Physics are time-reversible, what makes the difference between past and future? Entropy may increase, but how come it was low to begin with? And by-the-way, what happened even before it was at its lowest? And what if... working with toy model graph dynamics, could suggest simple CompSci answers to big Physics questions?

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.

Synthesis for Games of Imperfect Information under Full-Information Protocols

Jul 7 14:00 ₂₀₂₅

Monday 7 July 2025 at 14h00
ENS Paris-Saclay, Room 1B36 and online

Abstract: Different models can be used to represent programs, to check their correctness, or even better to synthesise them from a specification. Here, we model a program as a player against an environment. Constructing a correct program then boils down to synthesising a winning strategy in the associated game, that is, a behaviour that ensures that the winning condition is satisfied regardless of the behaviour of the environment.

We introduce a new class of games where the player receives imperfect information by communicating with passive observers in a full-information protocol. Unlike the classical model, the player can in one moment obtain an unbounded amount of information.

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Aspects of Category Theory in Proof Assistants

Jul 7 14:00 ₂₀₂₅

Monday 7 July 2025 at 14h00
ENS Paris-Saclay, Room 1B26

Abstract: While the use of proof assistants in mathematical research has yet to become the norm, an increasing number of results have been formalized. The prevalence of category theory in recent mathematical research indicates the need for its formalization in proof assistants. However, category theory is challenging to formalize for reasons we will explore.

The first difficulty is due to the fact that proposition equality in dependently typed theories as a structure that interacts in a complicated way with categories formalised inside those theories. We describe those challenges, and propose some solutions we explored to this problem.

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