Séminaires : Séminaire d'Algèbre

Equipe(s) : gr,
Responsables :J. Alev, D. Hernandez, B. Keller, Th. Levasseur, et S. Morier-Genoud.
Email des responsables : Jacques Alev <jacques.alev@univ-reims.fr>, David Hernandez <david.hernandez@imj-prg.fr>, Bernhard Keller <bernhard.keller@imj-prg.fr>, Thierry Levasseur <Thierry.Levasseur@univ-brest.fr>, Sophie Morier-Genoud <sophie.morier-genoud@imj-prg.fr>
Salle : Info sur https://researchseminars.org/seminar/paris-algebra-seminar
Adresse :
Description

Le séminaire est prévu en présence à l'IHP et à distance. Pour les liens et mots de passe, merci de contacter l'un des organisateurs ou de souscrire à la liste de diffusion https://listes.math.cnrs.fr/wws/info/paris-algebra-seminar. L'information nécessaire sera envoyée par courrier électronique peu avant chaque exposé. Les notes et transparents sont disponibles ici.

 

Since March 23, 2020, the seminar has been taking place remotely. For the links and passwords, please contact one of the organizers or

subscribe to the mailing list at https://listes.math.cnrs.fr/wws/info/paris-algebra-seminar. The connexion information will be emailed shortly before each talk. Slides and notes are available here.

 

Orateur(s) Valentin OVSIENKO - Reims,
Titre "Quantum'' rational numbers, q-deformed Coxeter friezes, and the cross-ratio
Date12/10/2026
Horaire14:00 à 15:00
Diffusion
Résume

The classical cross-ratio ``crosses'' both classical and modern mathematics, linking geometry with combinatorics, dynamics, and mathematical physics. It provides natural coordinates on many moduli spaces. In this talk, I will introduce a new q-deformed, or ``quantum'' cross-ratio: a PSL(2,Z)-invariant of ordered quadruples of distinct points on the rational projective line. The construction is based on the theory of q-deformed rational numbers developed jointly with Sophie Morier-Genoud. I will discuss several properties of this new invariant, with its close connection to q-deformed Coxeter frieze patterns taking centre stage.

This talk will take place in hybrid mode at the Institut Henri Poincaré.

SalleInfo sur https://researchseminars.org/seminar/paris-algebra-seminar
Adresse
© IMJ-PRG