Representation Theory, Geometry, and Mathematical Physics

A Conference in Honor of the 90th Birthday of A. A. Kirillov

Alexandre Alexandrovich Kirillov is one of the most influential mathematicians of the twentieth century. His pioneering work on the orbit method — linking coadjoint orbits of Lie groups to unitary representations — transformed the landscape of representation theory and has had profound and lasting impact across geometry, mathematical physics, and algebra. This conference celebrates his 90th birthday and the enduring legacy of his ideas, bringing together leading mathematicians whose work has been shaped by his vision.

Preliminary Invited Speakers:

Igor Frenkel, Yale University

Alexander Goncharov, Yale University

Vladimir Retakh, Rutgers University

Dennis Sullivan, Stony Brook University

Leon Takhtajan, Stony Brook University

Joseph Bernstein, Tel Aviv University Via Zoom

Victor Ginzburg, University of Chicago Via Zoom

David Kazhdan, Hebrew University Via Zoom

Nikita Nekrasov, SCGP, Stony Brook Via Zoom

Andrei Okounkov, Columbia University Via Zoom

Grigori Olshanski, HSE University Via Zoom

Valentin Ovsienko, University of Reims

Michael Pevzner, University of Reims

Yury Neretin , University of Graz Via Zoom

Nikolai Reshetikhin, Tsinghua University Via Zoom

Dmitry Fuchs, UC Davis Via Zoom

Leonid Makar-Limanov, Wayne University

Alexander Molev, University of Sydney Via Zoom

Organizing Committee:

• Pavel Etingof Massachusetts Institute of Technology
• Aleksei Borodin Massachusetts Institute of Technology
• Alexander Kirillov Jr. Stony Brook University

For more information, please email etingof@math.mit.edu
For hotel reservations and other logistics, please contact charmine.yapchin@stonybrook.edu

Spring 2026 Midwest Dynamical Systems Conference at the the University of Notre Dame
The latest incarnation in a series of conferences that has been held nearly every year for more than 50 years.  

Confirmed Speakers:
    Vitaly Bergelson (Ohio State University)
    Benjamin Call (University of Illinois at Chicago)
    Yan Mary He (University of Oklahoma)
    Adam Kanigowski (University of Maryland)  
    Kevin Pilgrim (Indiana University)
    Federico Rodriguez-Hertz (Penn State University)
    Dong Chen (Indiana University Indianapolis)
    Paul Apisa (University of Wisconsin)

Conference website:
    https://sites.nd.edu/midwestdynamicalsystems/

Please note the following in particular.
 - We are asking all attendees to register for the meeting.
 - There is a block of hotel rooms held for us until April 3 at a special rate at Ivy Court Inn on the edge of Notre Dame's campus.  The weekend seems to be a little busy, so it's probably good to take advantage of these rooms.
 - We have some funding available for participants with the usual preference for younger mathematicians.  To receive full consideration, please register and request funding by Monday, March 9.
 - The meeting will include a poster session.  Again, you can indicate interest in presenting when you register.
 
From the organizers,
Jeff Diller, Marlies Gerber, Nyima Kao

The 2026 Spring Dynamics Workshop at the University of Maryland will take place from April 9 to April 12 2026.  This is the latest of a long-running series of semi-annual workshops run by the dynamics groups at Penn State University  and the University of Maryland.

Special events include:
1) The Chernov Memorial Lectures by Dmitry Dolgopyat 
2) The 15th Michael Brin Prize in dynamical systems (April 10th)

More information, including registration and a list of speakers, can be found on the conference webpage: https://www-math.umd.edu/dynamics-conference.html

There are limited funds to support the participation of junior mathematicians and other mathematicians without access to travel funds. We encourage everyone who is planning on attending to register as soon as possible on the website.

Featured Speakers:

8am - 9am: Raphaël Krikorian (Ecole Polytechnique)
Title: Exotic rotation domains and Herman rings for quadratic Hénon maps
Abstract: Quadratic Hénon maps are polynomial automorphism of $\mathbb{C}^2$ of the form $h:(x,y)\mapsto (\lambda^{1/2}(x^2+c)-\lambda y,x)$.
They have constant Jacobian equal to $\lambda$ and they admit two fixed points. If $\lambda$ is on the unit circle (one says the
map $h$ is conservative) these fixed points can be elliptic or hyperbolic. In the elliptic case, a simple application of Siegel Theorem
shows (under a Diophantine assumption) that $h$ admits many quasi-periodic orbits with two frequencies in the neighborhood of its fixed
points. Surprisingly, in some hyperbolic cases, S. Ushiki observed some years ago what seems to be quasi-periodic orbits though no
Siegel disks exist. I will explain why this is the case. This theoretical framework also predicts and mathematically proves, in the
dissipative case ($\lambda$ of module less than 1), the existence of (attractive) Herman rings. These Herman rings, which were not
observed before, can be produced in numerical experiments.

9am - 10am: Bertrand Deroin (CNRS - CYU)
Title: Towards a Structural Stability Theory for Holomorphic Foliations on Algebraic Complex Surfaces
Abstract: I'll review work done in collaboration with Aurélien Alvarez, aiming at developing a theory of structural stability for
holomorphic foliations on compact complex surfaces. Important new examples are the Jouanolou foliations of the complex projective
plane, and the fundamental properties they satisfy allow us to define a more general family of foliations on arbitrary algebraic
surfaces, which we call Jouanolou-type foliations. I will present these conditions, as well as some of their properties, and, time
permitting, I will state a number of conjectures. 

10am - 11am: Giovanni Forni (CYU - University of Maryland)
Title: On the dynamics of billiards in polygons
Abstract: In this talk we will survey several results on the dynamics of billiards in polygons. These include results on their ergodic
theory (weak mixing), KAM-type results on stability of invariant surfaces of rational billiards under perturbations and existence of
periodic orbits. Part of the work is in collaboration with F. Arana Herrera and J. Chaika.

 Organizers: 

Zhiqiang Li (Peking University)

Misha Lyubich(Stony Brook University)

Michael Yampolsky(University of Toronto)