Institut de Recherche en Informatique Fondamentale (IRIF)


L'IRIF est une unité mixte de recherche (UMR 8243) entre le CNRS et l'Université de Paris, qui 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. Six de ses membres ont été lauréats de l'European Research Council (ERC), cinq 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.

Accepted papers STACS 2022

Two papers coauthored by IRIF members will be presented at the 39th International Symposium on Theoretical Aspects of Computer Science (STACS 2022) held in Marseille, March 15-18 2022.

Accepted papers POPL 2022

Three accepted papers coauthored by IRIF members will be presented at POPL 2022, the main conference on programming languages and programming systems, January 16-22.

hpcqs project

We are excited to be part of the “High-Performance Computer and Quantum Simulator hybrid” (HPCQS) aiming at creating a world-class supercomputing ecosystem. Learn more about the project here.

Giuseppe Castagna (IRIF), Mickaël Laurent (Université de Paris), Kim Nguyen (Université Paris Saclay) and Matthew Lutze (Université de Paris) will present their paper that shows a nifty way to use classic deduction rules to define a formal framework in which dynamic languages such as JavaScript can statically and precisely typed. Check the proof-of-concept implementation available at


Prochaine conférence dans le cadre des 75 ans d’informatique : L’informatique dans le 7ème art : fiction ou réalité ? Rendez-vous avec Fabrice Kordon le jeudi 9 décembre-18h00 sur le campus Pierre et Marie Curie de Sorbonne Université (tour 25.26, 1er étage – salle 105).

Accepted paper FOCS 2021

Adrian Vladu's paper Faster Sparse Minimum Cost Flow by Electrical Flow Localization, jointly written with Kyriakos Axiotis and Aleksander Madry, will be presented at FOCS 2021.


IRIF is very pleased to host for two months Serge Massar, Professor at the Université libre de Bruxelles (ULB) as part of the FSMP Distinguished Professor Fellowship. Serge Massar is the director of the Laboratoire d'Information Quantique (LIQ), of the Physics Department, Science Faculty, ULB. His research interests are quantum information theory, experimental quantum and non linear optics, machine learning.

Portrait Matej Stehlik

IRIF has the great pleasure to welcome a new professor in computer science at Université de Paris: Matěj Stehlík, an expert in graph theory. Learn more about him and his work here.

(Ces actualités sont présentées selon un classement mêlant priorité et aléatoire.)

Algorithmes et complexité
Mardi 25 janvier 2022, 14 heures, 3052
Simona Etinski (INRIA / IRIF) Latest challenges in post-quantum cryptography

In 2016, the National Institute of Standards and Technology (NIST) announced a call for standardization (also known as “NIST competition”) of post-quantum cryptographic protocols, i.e., cryptographic protocols considered to be resistant to quantum attacks. NIST was mainly interested in two types of protocols: digital signatures and encryption/key-establishment schemes. The fourth and final round of this competition is about to start, and once it is finished, the most efficient and thoroughly analyzed protocols will be standardized.

In this talk, we focus on the proposal for a digital signature. It is based upon a problem from coding theory, known as a syndrome decoding problem, and analyzed using cryptanalytic means. Namely, we analyze the time complexity of the information set decoding algorithms, widely believed to be the best algorithms for solving the syndrome decoding problem. By evaluating their complexity, both in the classical and quantum domain, we reason about the hardness of the problem. Finally, we give an example of the scheme based upon the syndrome decoding problem and analyze its security imposed by the hardness of the problem. We examine the tradeoff between signature's security and its size, which is a major challenge to be addressed in the competition.

One world numeration seminar
Mardi 25 janvier 2022, 14 heures 30, Online
Claudio Bonanno (Università di Pisa) Infinite ergodic theory and a tree of rational pairs

The study of the continued fraction expansions of real numbers by ergodic methods is now a classical and well-known part of the theory of dynamical systems. Less is known for the multi-dimensional expansions. I will present an ergodic approach to a two-dimensional continued fraction algorithm introduced by T. Garrity, and show how to get a complete tree of rational pairs by using the Farey sum of fractions. The talk is based on joint work with A. Del Vigna and S. Munday.

Combinatoire énumérative et analytique
Jeudi 27 janvier 2022, 14 heures, Salle 3052 et sur zoom
Elba Garcia-Failde (IMJ-PRG Sorbonne Universite) TBD

Preuves, programmes et systèmes
Jeudi 27 janvier 2022, 10 heures 30, Virtual room at link (any password works)
Titouan Carette (LORIA / Université de Lorraine) Diagrammatic semantics of quantum streams

In the same way we have streams of bits and stream transformer, we can define streams of qubits and qubit stream transformers. I will present an extension of quantum circuits with quantum memories to represent stream tranfsormers. We provide a set of rewriting rule and a coinduction principle that can extend any complete set of rules for cirucits to a complete set of rule for stream transformer. Thus, any two observationaly equivalent stream transformers can be proven equivalent using our rewriting rules. I will also expose ongoing works on the denotational semantics of stream transformers and extension to the post selectioned case.

Vendredi 28 janvier 2022, 14 heures 30, Salle 3052
Soumyajit Paul A Bridge between Polynomial Optimization and Games with Imperfect Recall

Graph Transformation Theory and Applications
Vendredi 28 janvier 2022, 15 heures, online
William Waites (University of Strathclyde, Scotland, UK) Rule-based Models of Epidemics

Rule-based models, a particular kind of graph rewriting system initially intended for use in molecular biology, are conspicuously useful for understanding epidemics. They enable formulation of complex processes that blends the ease of understanding of “compartmental” models with the expressiveness of individual- or agent-based models. We illustrate this with a story, told in graph rewriting rules, of how the adaptive immune response to a pathogen works (simplified version) and how this response influences the population level dynamics of an epidemic. This model can be calibrated against real-world data and we see how some of the individual heterogeneity that is normally treated phenomenologically in the study of epidemics arises naturally from this account of immune response.

Zoom meeting registration link

YouTube live stream

Combinatoire énumérative et analytique
Jeudi 3 février 2022, 14 heures, Salle 1007
Seminaire Flajolet d

Vendredi 4 février 2022, 14 heures 30, Salle 3052 (Online)
Bartek Klin Orbit-finite-dimensional vector spaces, with applications to weighted register automata

I will discuss vector spaces spanned by orbit-finite sets. These spaces are infinite-dimensional, but their sets of dimensions are so highly symmetric that the spaces have many properties enjoyed by finitely-dimensional spaces.

Applications of this include a decision procedure for equivalence of weighted register automata, which are the common generalization of weighted automata and register automata for infinite alphabets. The algorithm runs in exponential time, and in polynomial time for a fixed number of registers. As a special case, we can decide, with the same complexity, language equivalence for unambiguous register automata.

(Joint work with Mikołaj Bojańczyk and Joshua Moerman.)

Combinatoire énumérative et analytique
Jeudi 10 février 2022, 14 heures, Salle 1007
Daniel Tamayo Permutree Sorting

We define permutree sorting which generalizes the stack sorting and Coxeter sorting algorithms respectively due to Knuth and Reading. Given two disjoint subsets U and D of {2,…,n}, it consists of an algorithm that fails for a permutation if and only if there are integers i<j<k in [n] such that the permutation contains the pattern jki (resp. kij) if j is in U (resp. in D). We present this algorithm through automata that read reduced expressions and accept only those that form a specific structure within the weak order. This is joint work with Vincent Pilaud and Viviane Pons.

Graph Transformation Theory and Applications
Vendredi 11 février 2022, 15 heures, online
Pablo Arrighi (Université Paris-Saclay, France) Quantum Causal Graph Dynamics

Suppose that an entire graph evolves quantum mechanically and gets driven into superpositions of graphs of different connectivities and node populations. Suppose moreover that the evolution is causal, meaning that information can only propagate at a bounded speed, with respect to graph distance. We show that this quantum evolution must decompose into small, local unitary rewritings of graph disks. This unifies a result on Quantum Cellular Automata with another on Reversible Causal Graph Dynamics. To reach the result we formalize a notion of causality which is valid in the context of quantum superpositions of time-varying graphs, and has a number of good properties.

References: 1, 2, 3

Zoom meeting registration link

YouTube live stream