Création du Laboratoire Méthodes Formelles

Le Laboratoire Méthodes Formelles (LMF) est né le 1er janvier 2021 de la volonté politique de ses tutelles - Université Paris-Saclay, CNRS, ENS Paris-Saclay, Inria et CentraleSupélec - de créer un pôle ciblé sur les méthodes formelles. Le LMF est formé du Laboratoire Spécification et Vérification (LSV, ENS Paris-Saclay, CNRS, Inria) et de l’équipe Vals du Laboratoire de Recherche en Informatique (LRI, Université Paris-Saclay, CNRS, Inria, CentraleSupélec) soit une centaine de personnes.

Son ambition est d’éclairer le « monde numérique » grâce à la logique mathématique en utilisant les méthodes formelles comme outil d’analyse, de modélisation et de raisonnement pour les programmes informatiques, les protocoles de sécurité, etc. Il s'appuie sur des paradigmes de calcul des plus classiques aux plus novateurs comme l’informatique quantique.

Le LMF est structuré en pôles : son cœur de métier en comporte deux, « Preuves » et « Modèles » ; le troisième, « Interactions », est une ouverture à d’autres domaines tels que l’IA et la biologie.

Science ouverte : Prix pour Coq

L'assistant de preuves Coq est d'abord un langage informatique qui permet d'écrire des définitions et des énoncés mathématiques, de décrire des structures de données informatiques et des algorithmes. Il s’agit aussi d’un environnement pour développer des preuves de théorèmes complètement vérifiées par l'ordinateur, par exemple, la correction d'un algorithme. Read more...

ACM Software System Award for Jacques-Henri Jourdan / CompCert

Association for Computing Machinery (ACM) logo

Jacques-Henri Jourdan receives the 2021 ACM Software System Award together with Xavier Leroy, Sandrine Blazy, Zaynah Dargaye, Michael Schmidt, Bernhard Schommer, and Jean-Baptiste Tristan for their work on the CompCert formally verified compiler.

CompCert, initiated in 2005, is a compiler for the C programming language and the first industrial-strength compiler with a formally verified proof of correctness. It generates optimized code for most common computer architectures including PowerPC, ARM, RISC-V and x86.

The ACM Software System Award honours people or organizations "recognized for developing a software system that has had a lasting influence, reflected in contributions to concepts, in commercial acceptance, or both". The 2021 award is endowed with a prize of $35,000 sponsored by IBM.

Algorithm for consistent query answering under primary key constraints

Speaker: Anantha Padmanabha, ENS Ulm.

Tuesday May 10 2022, 11:00, (salle 1Z76 ENS Paris-Saclay and online)

Abstract: Databases often have constraints. However, these days it is common to have databases that violate such constraints. Such a database is called an “inconsistent database”. One of the basic constraints is the “primary key constraint” which states there can be at most one tuple for every primary key. If a database violates primary key constraint, it will contain more than one tuple for the same primary key. In this setting, the notion of a repair is defined by picking exactly one tuple for each primary key (maximal consistent subset of the database). A Boolean conjunctive query q, is certain for an inconsistent database D if q evaluates to true over all repairs of D. In this context, we have a dichotomy conjecture that states that for a fixed boolean conjunctive query q, testing whether q is certain for an input database D is either polynomial time or coNP-complete.

The conjecture is open in general, but has been verified for self-join-free and path queries. However, the polynomial time algorithms known in the literature are complex and use different strategies in the two cases. We propose a simple inflationary fixpoint algorithm for consistent query answering which correctly computes certain answers when the query q falls in the polynomial time cases for self-join-free queries and path queries. This raises a natural question, whether this algorithm works for all polynomial time cases. We answer this negatively and show that there are polynomial time certain queries (with self-joins) which cannot be computed by such an algorithm.

This is a joint ongoing work with Diego Figueira, Luc Segoufin and Cristina Sirangelo.

PhD Defence: Lulu He

Formal verification at design stage of diagnosis related properties for discrete event and real-time systems
by Lulu He
Wednesday 18 May 2022 at 10am
Room 435 (salle des thèses), building 650, 6 Rue Noetzlin, 91190 Gif-sur-Yvette.

Lulu He

Abstract: Fault diagnosis is a crucial and challenging task in the automatic control of complex systems, whose efficiency depends on a system property called diagnosability. Diagnosability describes the system property allowing one to determine at design stage whether a given fault occurring online will be identifiable with certainty based on the available observations, which is an alternative to testing that can only show the presence of failures without guaranteeing their absence. Read more...