# Séminaire Teich – 1er Octobre

Bonjour à toutes et à tous,

Ce vendredi le 1er octobre nous aurons le plaisir d’écouter Andrzej Bís de l’Université de Lodz
Avec un exposé Entropy, pressure and variational principle of semi-group actions.

Information importante : nous allons nous retrouver pas dans la salle du troisième étage (pas comme d’habitude !).

Voici le lien Zoom pour ceux et celles qui se joignent en ligne :
Et voici le résumé d’Andrzej :

Entropy, pressure and variational principle of semi-group actions
Abstract. The Krilov-Bogoliubov Theorem says that for continuous map $f:X \to X,$
of a compact metric space $X,$ there exists an $f-$invariant Borel probability measure. This result is essential in stating the variational principle for a single map.
There is no counterpart of the Krilov-Bogoliubov Theorem for a finitely generated
semi-group of continuous maps. During the talk I will provide some estimation
of topological entropy (in sense of Ghys, Langevin and Walczak) of a finitely generated semi-group action. Also, I will present a recent joint result with M. Carvalho, M. Mendes and P. Varandas on a general variational principle related to a pressure function.

À tout bientôt,
Thierry et Olga

# Séminaire Teich 24 Septembre

Bonjour à tous et toutes,
Notre séminaire continue ce vendredi 24 septembre à 11h à la Frumam avec l’exposé Strictly local self-assembly algorithm for a quasiperiodic octagonal tiling d’Ilya Galanov qui est arrivé cette année chez nous en ATER. Bienvenue, Ilya !
C’est encore en train de se décider si Ilya sera présent en vrai ou fera un exposé sur Zoom — de toute façon, ça sera retransmis :
Puis, l’emploi du temps de ce semestre est entièrement fixé, on vous laisse étudier le programme et le résumé d’Ilya (et une jolie image).
À tout bientôt,
Thierry et Olga
———
Self-assembly is the process in which the components of a system, whether molecules, polymers, or macroscopic particles, are organized into ordered structures as a result of local interactions between the components themselves, without exterior guidance. This talk is devoted to the self-assembly of aperiodic tilings. Aperiodic tilings serve as a mathematical model for quasicrystals – crystals that do not have any translational symmetry. Because of the specific atomic arrangement of these crystals, the question of how they grow remains open. Simulations strongly support the evidence that the algorithm we developed grows aperiodic cut-and-project tilings with local rules up to an unavoidable but neglectable proportion of missing tiles. In this talk, we state the first theorem regarding the Golden-Octagonal tilings and formulate conjectures for future results.

# Singularity Webinar -Thursday, September 16

Good morning,
The seminar from the Singularity Webinar from Marseille is back!
The next session will take place Thursday, September 16, from 14h to 15h (Paris time) via Zoom (see details below). We will have the pleasure to listen to:

Speaker: Michel Raibaut (Chambéry)
Title: Newton transformations and motivic invariants at infinity of plane curves

The abstractas well as the list of the forthcoming speakers, is available on the website of the webinarhttps://sites.google.com/view/singularites-marseille

The next talk will be in English, as well as future talks, in order to accommodate a larger public.

# Singularity Webinar -Thursday, June 24

Good morning
The next seminar from the Singularity Webinar from Marseille will take place Thursday, June 24, from 14h to 15h (Paris time) via Zoom (see details below). We will have the pleasure to listen to:

Speaker : Janusz ADAMUS (London, Ontario)
Title : Recent developments in arc-analytic geometry

The abstractas well as the list of the forthcoming speakers, is available on the website of the webinarhttps://sites.google.com/view/singularites-marseille

The next talk will be in English, as well as future talks, in order to accommodate a larger public

# Singularity Webinar -Thursday, June 17

Good morning,
The next seminar from the Singularity Webinar from Marseille will take place Thursday, June 17, from 14h to 15h (Paris time) via Zoom (see details below). We will have the pleasure to listen to:

Speaker : Baldur SIGURDSSON (Hanoi)
Title : Newton nondegenerate Weil divisors in toric varieties

The abstractas well as the list of the forthcoming speakers, is available on the website of the webinarhttps://sites.google.com/view/singularites-marseille

The next talk will be in English, as well as future talks, in order to accommodate a larger public.