## Bienvenue

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.

## Notion du jour

## Actualités

*19.10.2021*

Eugene Asarin (IRIF), Alexandre Donzé, Oded Maler, and Dejan Nickovic receive the Test of Time Award at the 21st International Conference on Runtime Verification (RV’21) for their paper Parametric Identification of Temporal Properties. Watch the RV’21 Award Announcement here.

*14.9.2021*

Eugene Asarin (IRIF), Thomas Ferrère, Dejan Ničković and Dogan Ulus receive the **Oded Maler best paper award in Timed Systems** at the conference Formats’2021 for their paper On the complexity of timed pattern matching.

*27.9.2021*

From ancient history to quantum, **learn about cryptography** at Fête de la science in an entertaining talk by Sylvain Perifel (IRIF). Save the date, **Monday October 4th, 10am** at Amphitheater 1A, Halle aux farines - Campus Grands Moulins.

*29.9.2021*

IRIF researchers are participating to the 30th edition of Fête de la Science. In different schools in Paris, they will be presenting workshops and games related to computer science.

*3.9.2021*

Guillaume Aubian, Pierre Charbit (IRIF) and Pierre Aboulker study the class of oriented graphs such that the out-neighbourhood of any vertex induces a transitive tournament and prove for it a decomposition theorem. As a consequence, they obtain that oriented graphs in this class have dichromatic number at most $2$ and satisfy Caccetta-Häggkvist conjecture.

*3.9.2021*

Reza Naserasr (IRIF) is an invited speaker at the 29th Workshop on Cycles and Colourings. He will present a joint work with Lan Anh Pham (IRIF), Zhouningxin Wang PhD student (IRIF) and Xuding Zhu (University Jinchua): Density of C –4 -critical signed graphs. There is a classic one-to-one correspondence between (2k+1)-colorability of a graph and mapping of a specific subdivision of it to the (2k+1)-cycle. In this work they present an extension of this to 2k-coloring using homomorphisms of signed graphs.

*3.9.2021*

Reza Naserasr and Zhouningxin Wang (IRIF) will present the notion of **circular coloring of signed graphs**, as a common extension of the circular coloring of graphs and the 0-free coloring of signed graphs. In this work, they consider the problem of finding the best upper bound of the circular chromatic number of restricted families of signed graphs. In particular, they show that every signed bipartite planar graph of negative-girth 6 admits a circular 3-coloring.

*1.9.2021*

**Three papers coauthored by IRIF Ph.D students** will be presented at the European Conference on Combinatorics, Graph Theory and Applications. Topics include oriented graphs, asymmetric hypergraphs and bipartite planar graphs.

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

## Agenda

Algorithmique distribuée et graphes

Mardi 26 octobre 2021, 14 heures, Salle 1007

**Sagnik Sen** (IIT Dharwad, India) *On homomorphisms of simple signed graphs of some families*

Homomorphisms of signed graphs have been attracting growing attention in the last decades, especially due to their strong connections to the theories of graph coloring and graph minors. These homomorphisms have been particularly studied through the scope of the chromatic number. In this work, we provide new results and bounds on the chromatic number of several families of signed graphs (planar graphs, triangle-free planar graphs, $K_n$-minor-free graphs, and bounded-degree graphs).

Joint work with: Bensmail, Das, Nandi, Pierron, Sopena

Sémantique

Mardi 26 octobre 2021, 10 heures 30, Exposé à distance sur Galène – salle 3052 virtuelle

**Thomas Ehrhard** (CNRS, Université de Paris) *Coherent Differentiation [Part 1]*

One world numeration seminar

Mardi 26 octobre 2021, 14 heures 30, Online

**Michael Baake** (Universität Bielefeld) *Spectral aspects of aperiodic dynamical systems*

Automates

Vendredi 29 octobre 2021, 14 heures 30, Salle 3052

**Nofar Carmeli** *The Fine-Grained Complexity of Answering Database Queries*