Séminaires à venir
We study homshifts: colourings of the regular infinite grid that avoid a finite set of forbidden patterns that are small and the same in every direction.
Homshifts are a restriction of the classical model of shifts of finite type. In contrast to the general case, where more or less everything is undecidable, many questions become tractable. The frontier between the decidable and undecidable problems in this model is still very much open.
I will talk about a series of recent results around the following problem: given a partial coloring, is it possible to complete it into a colouring of the entire grid (while avoiding forbidden patterns?).
This trip will take us through various mathematical vistas: homotopy of finite graphs, families of mixing properties, fundamental groups and cocycles of shifts, and some surprise backdoor undecidability results.
This talk comes from joint works with Nishant Chandgotia, Silvère Gangloff and Piotr Opocha.
L'homologie dite "polygraphique" a été introduite par Métayer et ses collaborateurs au début des années 2000, afin de généraliser certains résultats de Squier sur l'homologie des monoïdes. Dans cet exposé, je présenterai mes travaux qui ont permis, d'une part, de revisiter les fondements théoriques de cette théorie et, d'autre part, de la généraliser à des coefficients généraux, ouvrant ainsi des perspectives d'applications à l'homologie des foncteurs. Je discuterai également des limitations intrinsèques de l'homologie polygraphique en l'état actuel et esquisserai un programme de généralisation afin de dépasser ces limitations.
https://www.mathconf.org/agqt2026
We introduce an interacting particle system originating from a nucleation process and investigate the nucleation time as a function of the interaction strength, ranging from weak to strong. Using (uniform) propagation of chaos, we study the non-linear mean-field limit. A standard analysis yields a Yaglom limit conditionned on non-nucleation and its associated tails for the distribution of the nucleation time. The most surprising result arises in the strong interaction regime: the tails follow a decay, where denotes the nucleus size. This result is obtained through an application of the centre manifold theorem. This is a joint work with Frédéric Paccaut.
TBA
Oratrices et orateurs :
- Marie-Pierre Béal, LIGM Université Gustave Eiffel
- Michel Davydov, LMPA Université du Littoral Côte d'Opale
- Martin Leguil, CMLS École Polytechnique
- Barbara Schapira, IMAG Université de Montpellier
T.B.A.
T.B.A.