Schedule

April 17 - Pauwel Van Den Eeckhaut (Bonn)

Title: Local rigidity of self-joinings and factors of pro-nilsystems

Abstract:

Pro-nilsystems play a central role in ergodic structure theory: they are precisely the structured systems governing multiple ergodic averages. In this talk I will discuss a fundamental property of this class of dynamical systems, namely its stability under taking factors. More precisely, I will explain a direct proof that any factor of an ergodic $k$-step pro-nilsystem is again a $k$-step pro-nilsystem. The main new ingredient is a local rigidity result for ergodic self-joinings of nilsystems: any ergodic self-joining sufficiently close to the diagonal joining is in fact the graph joining of an automorphism. The key geometric input here is a ‘no small subnilmanifolds’ lemma. I will then sketch how this rigidity result can be used to prove the factor-closure of pro-nilsystems.

April 24 - Alexander Volberg (MSU and Bonn)

Title: TBA

Abstract:

TBA

May 1 - No Seminar

May 8 - Davi Castro-Silva (University of Cambridge)

Title: TBA

Abstract:

TBA

May 15 - Stefanos Lappas (Bonn)

Title: Sharp bilinear estimates for singular integral operators and their maximal counterparts with kernels in weighted spaces

Abstract:

We discuss the boundedness properties of bilinear singular integral operators (including their maximal versions) associated with rough homogeneous kernels on $R$. In particular, we focus on the $L^{p_1} (R) \times L^{p_2} (R) \to L^p (R)$ bounds in the optimal quasi-Banach range of exponents $1 < p_1 , p_2 < \infty$ and $1/2 < p < \infty$, when the angular component $\Omega$ of the kernel belongs to weighted $L^q$-spaces on the unit sphere $S^1$ and has vanishing integral. This talk is based on two joint works with Petr Honzík, Lenka Slavíková and Bae Jun Park.

May 22 - Elias Schuster (Bonn)

Title: TBA

Abstract:

TBA

May 29 - No Seminar

June 5 - Bonn-Cologne Analysis & PDE Workshop 2026

Location: Bonn

Schedule and Abstract: TBA

June 12 - TBA

Title: TBA

Abstract:

TBA

June 19 - Double Session

Talk 1 - 14:15 - Sebastián Muñoz (Paris)

Title: TBA

Abstract:

TBA

Talk 2 - 15:15 - Ying Wang (Basque Center for Applied Mathematics)

Title: TBA

Abstract:

TBA

June 26 - Joseph Adams (Heinrich-Heine-Universität Düsseldorf)

Title: TBA

Abstract:

TBA

July 3 - Double Session

Talk 1 - 14:15 - Ethan Ackelsberg (EPFL)

Title: TBA

Abstract:

TBA

Talk 2 - 15:15 - Tatjana Eisner (University of Leipzig)

Title: TBA

Abstract:

TBA

July 10 - Double Session

Talk 1 - 14:15 - Joris Roos (University of Massachusetts Lowell)

Title: TBA

Abstract:

TBA

Talk 2 - 15:15 - Polona Durcik (Chapman University)

Title: TBA

Abstract:

TBA

July 17 - Luka Milicevic (Serbian Academy of Sciences and Arts)

Title: TBA

Abstract:

TBA

July 24 - Lenka Slavikova (Charles University)

Title: TBA

Abstract:

TBA