





20.10.2021, 14:10 (Wednesday) 
Patrick IglesiasZemmour (CNRS, HUJI) 




Title: 
Every
symplectic manifold is a (linear) coadjoint orbit 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
I will show
how every symplectic manifold (Hausdorff and second
countable)
is a coadjoint orbit of the group of automorphisms of
its integration
bundle, for the linear coadjoint action, even when the
symplectic form
is not integral, i.e., when the group of periods is
dense in the real
line. In this case the integration bundle is not a
manifold because
its torus of period is not a circle but an "irrational
torus". This
theorem answers a question asked by a few students, in
particular on
MathOverFlow: Is there a universal model for symplectic
manifolds? The
answer is "yes". They are all coadjoint orbits. 









27.10.2021, 14:10
(Wednesday)

Daniel Tsodikovich (Tel Aviv University)





Title:

Billiard Tables with rotational symmetry 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
Consider the following simple geometric fact: the
only centrally symmetric
convex curve of constant width is a circle. The
condition of having constant
width is equivalent for the (Birkhoff) billiard map to
have a 1parameter
family of two periodic orbits. We generalize this
statement to curves that
are invariant under a rotation by angle
\frac{2\pi}{k}, for which the
billiard map has a 1parameter family of kperiodic
orbits. We will also
consider a similar setting for other billiard systems:
outer billiards,
symplectic billiards, and (a special case of) Minkowski
billiards.
Joint work with Misha Bialy.










03.11.2021, 16:10 (Wednesday) 
Egor Shelukhin (University of Montreal) 

(PLEASE NOTE CHANGE IN TIME!)






Title: 
Hamiltonian notorsion 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
We generalize in several ways Polterovich's
wellknown theorem that the
Hamiltonian group of a closed symplectically aspherical
manifold admits
no nontrivial elements of finite order. We prove an
analogous statement
for CalabiYau and negatively monotone manifolds. For
positively monotone
manifolds we prove that nontrivial torsion implies
geometric uniruledness
of the manifold, answering a question of McDuffSalamon.
Moreover, in this
case the following symplectic Newman theorem holds: a
small Hoferball
around the identity contains no finite subgroup. This is
joint work with
Marcelo Atallah.









10.11.2021, 14:10 (Wednesday)

Umut Varolgunes (Stanford University, University
of Edinburgh)





Title: 
Trying to quantify Gromov's nonsqueezing theorem 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
Gromov's celebrated result says (colloquially)
that one cannot symplectically
embed a ball of radius 1.1 into a cylinder of radius 1.
I will show that in
4d if one removes from this ball a Lagrangian plane
passing through the
origin, then such an embedding becomes possible. I will
also show that this
gives the smallest Minkowski dimension of a closed
subset with this property.
I will end with many questions. This is based on joint
work with K. Sackel,
A. Song and J. Zhu. 









17.11.2021, 14:10 (Wednesday) 
Pazit Haim Kislev (Tel Aviv
University) 




Title: 
Symplectic capacities of pproducts 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
In this talk we discuss
symplectic capacities of convex domains and their
behavior with respect to symplectic pproducts. One
application, by using
a "tensor power trick", is to show that it is enough to
prove Viterbo's
volumecapacity conjecture in the asymptotic regime when
the dimension is
sent to infinity. In addition, we introduce a conjecture
about higher order
capacities of pproducts and show that if it holds then
there are no
nontrivial pdecompositions of the symplectic ball.










24.11.2021, 14:10 (Wednesday) 
Gerhard Knieper (Ruhr University Bochum) 




Title: 
Growth rate of closed geodesics on surfaces
without conjugate points. 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
Let (M,g) be a closed Riemannian surface of of
genus at least 2 and no
conjugate points. By the uniformization theorem such a
surface admits
a metric of negative curvature and therefore the
topological entropy h
of the geodesic flow is positive. Denote by P(t)
the number of free
homotopy classes containing a closed geodesic of
period $\le t $. We
will show: P(t) is asymptotically equivalent to
e^(ht)/(ht) =F(t), i.e.
the ratio of P and F converges to 1 as t tends to
infinity.
An important ingredient in the proof is a mixing flow
invariant measure
given by the unique measure of maximal entropy. Under
suitable hyperbolicity
assumptions this result carries over to closed
Riemannian manifolds without
conjugate and higher dimension.
For closed manifolds of negative curvature the above
estimate is well known
and has been originally obtained by Margulis. In a
recent preprint
the estimate has been also obtained by Ricks for
certain closed manifolds
(rank 1 mflds) of nonpositive curvature. This is a
joint work with Vaughn
Climenhaga and Khadim War. 









01.12.2021, 14:10 (Wednesday) 
Sara Tukachinsky (Tel Aviv University) 




Title: 
Bounding chains as a tool in open GromovWitten
theory 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
Moduli spaces of Jholomorphic disks have
boundary. This interferes with
desirable structures, such as Lagrangian Floer theory or
open GromovWitten
invariants. One tool for balancing out boundary
contributions is a bounding
chain. In this talk I will give some background on the
problem, then discuss
in detail what bounding chains are, how they can be
constructed, and how
they are used to define invariants.
The work of several people will be mentioned, among them
a joint work
with J. Solomon. 









08.12.2021, 14:10 (Wednesday) 
Louis Ioos (Max Planck Institute) 




Title: 
Quantization in stages and canonical metrics 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
In this talk, I will
introduce the notion of quantization in stages, which
lies at the basis of fundamental physical setups such
as the SternGerlach
experiment, and explain how it can be realized over
compact symplectic phase
spaces via the use of BerezinToeplitz quantization of
vector bundles. In
particular, I will introduce and show how to compute the
associated quantum
noise. I will then describe an application to
HermiteEinstein metrics on
stable vector bundles over a projective manifold, and if
time permits, I will
show how a refinement of these results in the case of
the trivial line bundle
can be applied to Kähler metrics of constant scalar
curvature. 









15.12.2021, 14:10 (Wednesday) 
Philippe Charron (Technion)





Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









22.12.2021, 17:10 (Wednesday) 
Simion Filip
(University of Chicago) 

(PLEASE NOTE CHANGE IN TIME!)






Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









05.01.2022, 14:10 (Wednesday) 
Igor Uljarević (University of Belgrade) 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









02.03.2022, 14:10 (Wednesday) 
Joé Brendel (University of Neuchâtel) 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









09.03.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









16.03.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









23.03.2022, 14:10 (Wednesday) 
TBA





Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









30.03.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









06.04.2022, 14:10 (Wednesday) 
ShengFu Chiu (Institute of Mathematics, Academia
Sinica, Taiwan) 




Title: 
From EnergyTime Uncertainty to Symplectic
Displacement Energy 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
Heisenberg's Uncertainty Principle is one of the
most celebrated features of
quantum mechanics, which states that one cannot
simultaneously obtain the
precise measurements of two conjugated physical
quantities such as the pair
of position and momentum or the pair of electric
potential and charge density.
Among the different formulations of this fundamental
quantum property, the
uncertainty between energy and time has a special place.
This is because the
time is rather a variable parametrizing the system
evolution than a physical
quantity waiting for determination. Physicists working
on the foundation of
quantum theory have understood this energytime relation
by a universal bound
of how fast any quantum system with given energy can
evolve from one state to
another in a distinguishable (orthogonal) way. Recently,
there have been many
arguing that this bound is not a pure quantum phenomenon
but a general
dynamical property of Hilbert space. In this talk, in
contrast to the usual
Hilbert space formalism, we will provide a homological
viewpoint of this
evolutional speed limit based on a persistencelike
distance of the derived
category of sheaves : during a time period what is the
minimal energy needed
for a system to evolve from one sheaf to a status that
is distinguishable from
a given subcategory? As an application, we will also
discuss its geometric
incarnation in the dynamics of classical mechanics,
namely the notion of
symplectic displacement. We will see how this
categorical energy manages to
characterize the symplectic energy for disjointing a
Lagrangian from an open set. 









27.04.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









11.05.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









18.05.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









25.05.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









01.06.2022, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 









08.06.2021, 14:10 (Wednesday) 
TBA 




Title: 
TBA 

Location: 
Zoom session, the link is available upon request
by email 




Abstract: 
TBA 





