Bienvenue L'IRIF est une unité mixte de recherche (UMR 8243) entre le CNRS et l'Université Paris Cité, et héberge une équipe-projet Inria. Les recherches menées à l'IRIF reposent sur l’étude et la compréhension des fondements de toute l’informatique, afin d’apporter des solutions innovantes aux défis actuels et futurs des sciences numériques. L'IRIF regroupe près de deux cents personnes. Sept de ses membres ont été lauréats de l'European Research Council (ERC), trois sont membres de l'Institut Universitaire de France (IUF), deux sont membres de l'Academia Europæa, et un est membre de l'Académie des sciences. Notion du jour Réseaux Sociaux Suivez nous sur Mastodon, Twitter/X et LinkedIn : Actualités 27.3.2024 Marie-Josée Iarifina a rejoint l'IRIF pour remplacer Natalia Hacquart en tant que gestionnaire financière et comptable. Venez la rencontrer et lui souhaiter la bienvenue dans le bureau 4002. 28.3.2024 La Société mathématique de Belgique (SMB) a décerné à Mirna Džamonja (CNRS, IRIF, Université de Paris) le “Prix Godeaux” de la SMB. “Ce prix est décerné chaque année, sur proposition d'un membre du conseil d'administration de la BMS, à un-e mathématicien-ne belge ou international-e de renom qui est invité-e à donner une conférence en Belgique”. Toutes nos félicitations ! 15.3.2024 La deuxième conférence “On éteint, on réfléchit, on discute”, organisée à l'Université Paris Cité par François Laroussinie, portera sur “Les communs numériques”. Serge Abiteboul et Valérie Peugeot sont les conférenciers invités. Elle se tiendra le 19 mars 2024, de 16h à 18h. Cet événement est gratuit. 12.4.2024 La rediffusion de la conférence (en anglais) de Véronique Cortier, qui s'est tenue en février, est désormais disponible sur la chaîne YouTube de l'IRIF. Son sujet était : “Le vote électronique : conception et vérification formelle”. 10.4.2024 Trois projets de médiation scientifique de chercheurs à l'IRIF ont été sélectionnés pour l'édition 2024 de Pint of Science France-Paris. Le principe : découvrir une thématique ou un sujet scientifique, dans un bar. Nos chercheurs parleront protection des données, graphes et informatique quantique. 27.3.2024 Nous accueillons une nouvelle directrice de recherche à l'IRIF, Tayssir Touili. Ses domaines d'intérêt sont la détection de logiciels malveillants, la vérification de logiciels et les méthodes formelles. Vous pouvez la rencontrer dans le bureau 4028A. 29.3.2024 Bravo à Quentin Aristote, doctorant, qui a reçu le prix Helena Rasiowa pour le meilleur papier étudiant, lors de la 32ème conférence EACSL : Active Learning of Deterministic Transducers with Outputs in Arbitrary Monoids. 10.4.2024 L'IRIF a le plaisir d'annoncer son deuxième Distinguished Talk de l'année ! Notre conférencier invité est Omer Reingold, professeur d'informatique à l'université de Stanford et directeur de la Simons Collaboration sur la théorie de l'Équité algorithmique (Simons Foundation). Il parlera de l'équité algorithmique. Toute personne intéressée est invitée à se joindre à nous pour cette conférence ! edit toutes les anciennes actualités (Ces actualités sont présentées selon un classement mêlant priorité et aléatoire.) Agenda Vérification Lundi 13 mai 2024, 11 heures, 3052 and Zoom link Enrique Román Calvo (IRIF) Dynamic Partial Order Reduction for Checking Correctness against Transaction Isolation Levels Modern applications, such as social networking systems and e-commerce platforms are centered around using large-scale databases for storing and retrieving data. Accesses to the database are typically enclosed in transactions that allow computations on shared data to be isolated from other concurrent computations and resilient to failures. Modern databases trade isolation for performance. The weaker the isolation level is, the more behaviors a database is allowed to exhibit and it is up to the developer to ensure that their application can tolerate those behaviors. In this work, we propose stateless model checking algorithms for studying correctness of such applications that rely on dynamic partial order reduction. These algorithms work for a number of widely-used weak isolation levels, including Read Committed, Causal Consistency, Snapshot Isolation and Serializability. We show that they are complete, sound and optimal, and run with polynomial memory consumption in all cases. We report on an implementation of these algorithms in the context of Java Pathfinder applied to a number of challenging applications drawn from the literature of distributed systems and databases. IRIF Distinguished Talks Series Mardi 14 mai 2024, 11 heures, TBA Omer Reingold (Stanford) The multitude of group affiliations: Algorithmic Fairness, Loss Minimization and Outcome Indistinguishability We will survey a rather recent and very fruitful line of research in algorithmic fairness, coined multi-group fairness. We will focus on risk prediction, where a machine learning algorithm tries to learn a predictor to answer questions of the form “what is the probability that patient x will experience a particular medical condition?” Training a risk predictor to minimize a loss function fixed in advance is the dominant paradigm in machine learning. However, global loss minimization may create predictions that are mis-calibrated on sub-populations, causing harm to individuals of these populations. Multi-group fairness tries to prevent forms of discrimination to a rich (possibly exponential) collection of arbitrarily intersecting groups. In a sense, it provides a computational perspective on the meaning of individual risks and the classical tension between clinical prediction, which uses individual-level traits, and actuarial prediction, which uses group-level traits. While motivated in fairness, this alternative paradigm for training an indistinguishable predictor is finding a growing number of appealing applications, where the same predictor can later be used to optimize one of a large set of loss functions, under a family of capacity and fairness constraints and instance distributions. Based on a sequence of works joint with (subsets of) Cynthia Dwork, Shafi Goldwasser, Parikshit Gopalan, Úrsula Hébert-Johnson, Lunjia Hu, Adam Kalai, Christoph Kern, Michael P. Kim, Frauke Kreuter, Guy N. Rothblum, Vatsal Sharan, Udi Wieder, Gal Yona and others. Séminaire des membres non-permanents Jeudi 16 mai 2024, 16 heures, Salle 3052 Clément Ducros How to Achieve Secure Computation Using Coding Theory? Secure Multiparty Computation (MPC) aims at enabling different parties to compute functions based on private inputs. Providing the parties with additional correlated and random inputs enables highly efficient MPC protocols. But how do we construct this additional correlated randomness? In this presentation, I will discuss the construction of pseudorandom correlation generators (PCG), focusing on the special case of two-party random oblivious linear evaluations (OLEs). We will explore the foundational concepts introduced by Boyle et al. (2020), examine their limitations, and demonstrate how coding theory significantly contributes to the security analysis and efficiency of the construction. This presentation is based on collaborative work with Maxime Bombar, Dung Bui, Geoffroy Couteau, Alain Couvreur, and Sacha Servan-Schreiber. Catégories supérieures, polygraphes et homotopie Vendredi 17 mai 2024, 14 heures, Salle 3058 Lyne Moser New methods to construct model categories Model categories provide a good environment to do homotopy theory. A model category consists of a bicomplete category together with three classes of morphisms (weak equivalences, cofibrations, and fibrations) satisfying a list of axioms. While weak equivalences are the main players in a model category and encode how two objects should be thought of as being ``the same, the additional data of cofibrations and fibrations typically facilitates computations of homotopy limits and colimits, and of derived functors. However, because of their robust structure, model categories are usually hard to construct. In joint work with Guetta, Sarazola, and Verdugo, we develop new techniques for constructing model structures from given classes of cofibrations, fibrant objects, and weak equivalences between them. The requirement that one only needs to provide a class of weak equivalences between fibrant objects both simplifies the conditions to check and seems more natural in practice: often, the fibrant objects are the ``well-behaved objects in a model category and so the weak equivalences should only be expected to exhibit a good behavior between these objects. As a straightforward consequence of our result, we obtain a more general version of the usual right-induction theorem along an adjunction, where fibrations and weak equivalences are now only right-induced between fibrant objects; we refer to such an induced model structure as fibrantly-induced. As applications of these new methods, we construct several model structures on the category of double categories. Automates Vendredi 17 mai 2024, 14 heures, Salle 3052 Laure Daviaud Stuff around weighted automata Combinatoire énumérative et analytique Mardi 21 mai 2024, 11 heures, Salle 3058 Jang Soo Kim (Sungkyunkwan University (SKKU)) Non encore annoncé. Algorithmes et complexité Mardi 21 mai 2024, 15 heures, Salle 4052 (PCQC) Xiaodi Wu (University of Maryland) Non encore annoncé. Algorithmes et complexité Mardi 21 mai 2024, 14 heures, Salle 3052 Lawrence Roy (Aarhus University) Non encore annoncé. One world numeration seminar Mardi 21 mai 2024, 14 heures, Online Gaétan Guillot (Université Paris-Saclay) Approximation of linear subspaces by rational linear subspaces We elaborate on a problem raised by Schmidt in 1967: rational approximation of linear subspaces of $\mathbb{R}^n$. In order to study the quality approximation of irrational numbers by rational ones, one can introduce the exponent of irrationality of a number. We can then generalize this notion in the framework of vector subspaces for the approximation of a subspace by so-called rational subspaces. After briefly introducing the tools for constructing this generalization, I will present the different possible studies of this object. Finally I will explain how we can construct spaces with prescribed exponents. Preuves, programmes et systèmes Jeudi 23 mai 2024, 10 heures 30, ENS Lyon Tba Séminaire CHOCOLA