Seminars are given every Friday from 2:00 to 3:00 (usually in room 178, but not for the time being). You are welcome 10 minutes earlier for tea, coffee and cake.

In order to receive the announcements, just send an email to with subject "subscribe labri.go-gt Cookie Monster", where Cookie is your first name and Monster your last name.

See the agenda of the seminars:; to add it to yours , or flash the following QRCode:

Next talks:

The online talks are available here :

Vendredi 23 février à 14h - Pierre Bonnet
Separating variables with graph homology
The enumeration of walks in the quarter plane has attracted a lot of attention over the past twenty years, involving a wide range of techniques. In the context of the study of the functional equations that occur for walks with large steps, a graph called the orbit of the walk has been introduced by Bostan, Bousquet-Mélou and Melczer in 2018, which turned out to be useful to simplify and characterize these equations. It however lacked a group structure. In this presentation, I will show how the addition of such a group acting on the orbit, arising from Galois theory, sheds a new light on the structure of this graph. In particular, I will demonstrate how this new structure coupled with the use of graph homology allows to solve the question of separating variables in these functional equations. This is joint work with Charlotte Hardouin.



GT Graphs and Optimization


 Previous Years

edit SideBar

Blix theme adapted by David Gilbert, powered by PmWiki