Geometry & Dynamics Seminar 2025-26


Some seminar talks will take place in Schreiber Building, room 309, and in addition 

will be broadcasted via the zoom app, while other talks will run entirely via the zoom app.

The seminar will take place on Wednesdays at 14:10.

Please check each announcement since this is sometimes changed. 

The zoom link is available upon request by email.

 

 

Upcoming Talks        Previous Talks        Previous Years










29.10.2025, 14:10 (Wednesday) Bernard Derrida (Collège de France, Paris) - MINT Distinguished Lecture
Joint meeting of Geometry and Dynamics Seminar
and Horowitz Seminar "Probability, Ergodic Theory
and Dynamical Systems"





Title: The many faces of the Fisher-KPP equation
Location: Schreiber 309 and zoom session



Abstract: The Fisher-KPP equation, introduced in 1937 by the biologist Fisher
and the mathematicians Kolmogorov, Petrovsky, and Piscounov, describes
the growth of a stable region into an unstable medium. It is one of
the classical examples of a traveling wave equation that exhibits
the phenomenon of velocity selection. For physicists and biologists,
it appears in many other contexts, ranging from the theory of
disordered systems to reaction–diffusion problems, branching Brownian
motion, and models of evolution with selection. It is also related
to a number of mathematical questions in probability, PDEs,
stochastic PDEs, and complex analysis. This talk will review
some classical results as well as recent progress.








05.11.2025, 14:10 (Wednesday)
Cheuk Yu Mak (University of Sheffield)




Title:
C^0-rigidity of the Hamiltonian diffeomorphism group of symplectic rational surfaces
Location: Zoom session and screening in Schreiber 309



Abstract: We investigate the problem of the C^0 closure of Symp_0 in Symp.
Borrowing techniques from the study of mapping class groups of
symplectic rational surfaces, we show that for most of the positive
symplectic rational surfaces, Symp_0 is a connected component of
Symp in the C^0 topology. This is a joint work with Marcelo
Atallah and Weiwei Wu.









12.11.2025, 14:10 (Wednesday) Shmuel Weinberger (UChicago)



Title: Morse complexity of homology classes
Location: Schreiber 309 and zoom session



Abstract: In the 1970's Gromov (motivated by ideas of Thurston) introduced
a pseudonorm on the homology of a space based on the minimum
number of simplices it takes to represent the class.  This
concept has proved enormously useful in many investigations. 
In this talk, I will discuss the much more elusive concept
based on minimizing the number of critical points in a Morse
function for a manifold representative of the homology class. 
In dimension two, these are essentially the same idea, but
they differ in higher dimensions.  I will explain the little
that we know about this measurement which relates to some
classical topology (most interestingly open book decompositions,
and surgery theory), representation theory and elliptic
operators (for the very few nonzero estimates we know). 
(Joint work with Manin and Tshishiku)








19.11.2025, 14:10 (Wednesday)
Mark Berezovik (TAU)



Title: Billiards and Hofer's Geometry
Location: Schreiber 309 and zoom session



Abstract: In this talk I will discuss a link between billiards in convex
planar domains and Hofer’s geometry. For smooth strictly convex
billiard tables the Hofer distance between the corresponding
billiard ball maps admits an upper bound in terms of a simple
geometric distance between the tables. Using this result one can
embed the billiard ball map of a convex polygon in the completion,
with respect to Hofer's metric, of the group of smooth area-preserving
maps of the annulus. This talk is based on joint work with Konstantin
Kliakhandler, Yaron Ostrover, and Leonid Polterovich.








26.11.2025, 14:10 (Wednesday) Shah Faisal (University of Strasbourg, Uppsala University)



Title: TBA
Location: Zoom session and screening in Schreiber 309



Abstract: TBA








03.12.2025, 14:10 (Wednesday) Maksim Stokic (Uppsala University)



Title: TBA
Location: Schreiber 309 and zoom session



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10.12.2025, 14:10 (Wednesday) TBA



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17.12.2025, 14:10 (Wednesday) TBA



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24.12.2025, 14:10 (Wednesday) TBA



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31.12.2025, 14:10 (Wednesday) TBA



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07.01.2026, 14:10 (Wednesday) TBA



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14.01.2026, 14:10 (Wednesday) Sergei Tabachnikov (Penn State)



Title: A tale of four billiards (with a focus on the nonconventional ones)
Location: Schreiber 309 and zoom session



Abstract: A periodic orbit of a Birkhoff billiard is a polygon of extremal
perimeter inscribed into the billiard table (a plane oval).
One may replace the word "perimeter" by "area" and/or the word
"inscribed" by "circumscribed". This provides three other
billiard-like systems. Two of them, involving area, can be
generalized to symplectic spaces, with the symplectic structure
replacing the area form; this gives symplectic inner and outer
billiards.
I shall discuss properties of the symplectic outer billiards,
including periodic orbits and the large scale behavior of its
trajectories. I shall also discuss the large scale behavior of
the trajectories of the planar outer length billiards. Finally,
I will relate the inner symplectic billiards with still another
billiard-like system, the Minkowski billiards, currently a popular
subject of study in symplectic topology.








21.01.2026, 14:10 (Wednesday)
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18.03.2026, 14:10 (Wednesday)
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25.03.2026, 14:10 (Wednesday) TBA



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15.04.2026, 14:10 (Wednesday) TBA



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29.04.2026, 14:10 (Wednesday) TBA



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06.05.2026, 14:10 (Wednesday) TBA




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13.05.2026, 14:10 (Wednesday) TBA



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20.05.2026, 14:10 (Wednesday) TBA



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27.05.2026, 14:10 (Wednesday) TBA



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03.06.2026, 14:10 (Wednesday) TBA



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10.06.2026, 14:10 (Wednesday) TBA



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17.06.2026, 14:10 (Wednesday) TBA



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24.06.2026, 14:10 (Wednesday) TBA



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01.07.2026, 14:10 (Wednesday) TBA



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Organized by Misha Bialy, Lev Buhovsky, Yaron Ostrover, and Leonid Polterovich