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BEGIN:VEVENT
SUMMARY:Michael Entov (Technion)
DTSTART;VALUE=DATE-TIME:20200422T111000Z
DTEND;VALUE=DATE-TIME:20200422T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/1
DESCRIPTION:Title: Rigi
dity of Lagrangian tori in K3 surfaces\nby Michael Entov (Technion) as
part of Geometry and Dynamics seminar\n\n\nAbstract\nA Kahler-type form i
s a symplectic form compatible with an integrable \ncomplex structure. She
ridan and Smith previously proved\, using deep \nmethods of homological mi
rror symmetry\, that for any Maslov-zero \nLagrangian torus L in a K3 surf
ace M equipped with a Kahler-type \nform of a *particular kind*\, the inte
gral homology class of L has \nto be non-zero and primitive. I will discus
s how to extend this \nresult to *arbitrary* Kahler-type forms on M using
dynamical \nproperties of the action of the diffeomorphism group of M on t
he \nspace of such forms. These dynamical properties are obtained using \n
a version of Ratner's theorem. This is a joint work in progress \nwith M.V
erbitsky.\n
LOCATION:https://researchseminars.org/talk/GDS/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Boris Vertman (University of Oldenburg)
DTSTART;VALUE=DATE-TIME:20200506T111000Z
DTEND;VALUE=DATE-TIME:20200506T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/2
DESCRIPTION:Title: Mean
curvature flow in Lorentzian space times\nby Boris Vertman (Universit
y of Oldenburg) as part of Geometry and Dynamics seminar\n\n\nAbstract\nHy
persurfaces of zero or constant mean curvature play a central \nrole in th
e proof of the Positive Mass Theorem and also in the \nanalysis of the Cau
chy problem for asymptotically flat space-times. \nMean curvature flow can
be a tool to construct such hypersurfaces. \nWe discuss local existence o
f the flow for non-compact space-like \nhypersurfaces in Robertson-Walker
space-times. This is a joint project \nwith Giuseppe Gentile.\n
LOCATION:https://researchseminars.org/talk/GDS/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Louis Ioos (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20200513T111000Z
DTEND;VALUE=DATE-TIME:20200513T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/3
DESCRIPTION:Title: Almo
st-representations of the Lie algebra of SU(2) and quantization of the sph
ere\nby Louis Ioos (Tel Aviv University) as part of Geometry and Dynam
ics seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GDS/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tsachik Gelander (Weizmann Institute of Science)
DTSTART;VALUE=DATE-TIME:20200520T111000Z
DTEND;VALUE=DATE-TIME:20200520T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/4
DESCRIPTION:Title: Conv
ergence of normalized Betti numbers in nonpositive curvature\nby Tsach
ik Gelander (Weizmann Institute of Science) as part of Geometry and Dynami
cs seminar\n\n\nAbstract\nI will show that if X is any symmetric space oth
er than 3-dimensional \nhyperbolic space and M is any finite volume manifo
ld that is a quotient \nof X\, then the normalized Betti numbers of M are
"testable"\, i.e. one \ncan guess their values by sampling the manifold at
random places. This \nis joint with Abert\, Biringer and Bergeron\, and e
xtends some of our \nolder work with Nikolov\, Raimbault and Samet. The co
ntent of the recent \npaper involves a random discretization process that
converts the "thick \npart" of M into a simplicial complex\, together with
analysis of the \n"thin parts" of M. As a corollary\, we obtain that when
ever X is a higher \nrank irreducible symmetric space and M_i is any seque
nce of distinct \nfinite volume quotients of X\, the normalized Betti numb
ers of the M_i \nconverge to the "L^2-Betti numbers" of X.\n
LOCATION:https://researchseminars.org/talk/GDS/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Victor Ivrii (University of Toronto)
DTSTART;VALUE=DATE-TIME:20200527T111000Z
DTEND;VALUE=DATE-TIME:20200527T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/5
DESCRIPTION:Title: Heav
y atoms and molecules: Thomas-Fermi and Scott approximations\nby Victo
r Ivrii (University of Toronto) as part of Geometry and Dynamics seminar\n
\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GDS/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Mazzucchelli (ENS de Lyon)
DTSTART;VALUE=DATE-TIME:20200603T111000Z
DTEND;VALUE=DATE-TIME:20200603T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/6
DESCRIPTION:Title: Clos
ed geodesics on reversible Finsler 2-spheres\nby Marco Mazzucchelli (E
NS de Lyon) as part of Geometry and Dynamics seminar\n\n\nAbstract\nIn thi
s talk\, I will show that two celebrated theorems on closed \ngeodesics of
Riemannian 2-spheres still hold for the larger class \nof reversible Fins
ler 2-spheres: Lusternik-Schnirelmann's theorem \nasserting the existence
of three simple closed geodesics\, and \nBangert-Franks-Hingston's theorem
asserting the existence of \ninfinitely many closed geodesics. I will ske
tch the proofs of \nthese statements\, employing in particular the Finsler
generalization \nof Grayson's curve shortening flow developed by Angenent
-Oaks. \nThis is joint work with Guido De Philippis\, Michele Marini\, and
\nStefan Suhr.\n
LOCATION:https://researchseminars.org/talk/GDS/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ran Tessler (Weizmann Institute of Science)
DTSTART;VALUE=DATE-TIME:20200617T111000Z
DTEND;VALUE=DATE-TIME:20200617T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/8
DESCRIPTION:Title: Open
r-spin intersection theory\nby Ran Tessler (Weizmann Institute of Sci
ence) as part of Geometry and Dynamics seminar\n\n\nAbstract\nIn 1992 Witt
en conjectured that the intersection theory on the moduli \nof r-spin curv
es gives rise to a Gelfand Dickey tau function\, and \nproved his conjectu
re in genus 0.\nRecently\, in a joint work with Buryak and Clader we made
a similar \nconjecture/construction in the open setting:\nWe conjectured t
hat intersection theory on the moduli of r-spin \nsurfaces with boundaries
should give rise to the Gelfand Dickey *wave* \nfunction and proved it in
genus 0. In my talk I will describe all this\, \nin particular\, I'll exp
lain what is an r-spin structure\, what is the \nGelfand-Dickey hierarchy
and what is the motivation. If time permits\, \na mirror theorem (based on
work with Gross and Kelly) will also be shown.\n
LOCATION:https://researchseminars.org/talk/GDS/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emanuel Milman (Technion)
DTSTART;VALUE=DATE-TIME:20200622T111000Z
DTEND;VALUE=DATE-TIME:20200622T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/9
DESCRIPTION:Title: Func
tional Inequalities on sub-Riemannian manifolds via QCD\nby Emanuel Mi
lman (Technion) as part of Geometry and Dynamics seminar\n\n\nAbstract\nWe
are interested in obtaining Poincare and log-Sobolev inequalities \non do
mains in sub-Riemannian manifolds (equipped with their natural \nsub-Riema
nnian metric and volume measure).\n\nIt is well-known that strictly sub-Ri
emannian manifolds do not satisfy \nany type of Curvature-Dimension condit
ion CD(K\,N)\, introduced by \nLott-Sturm-Villani some 15 years ago\, so w
e must follow a different \npath. We show that while ideal (strictly) sub-
Riemannian manifolds do \nnot satisfy any type of CD condition\, they do s
atisfy a quasi-convex \nrelaxation thereof\, which we name QCD(Q\,K\,N). A
s a consequence\, these \nspaces satisfy numerous functional inequalities
with exactly the same \nquantitative dependence (up to a factor of Q) as t
heir CD counterparts. \nWe achieve this by extending the localization para
digm to completely \ngeneral interpolation inequalities\, and a one-dimens
ional comparison \nof QCD densities with their "CD upper envelope". We th
us obtain the \nbest known quantitative estimates for (say) the L^p-Poinca
re and \nlog-Sobolev inequalities on domains in the ideal sub-Riemannian s
etting\, \nwhich in particular are independent of the topological dimensio
n. For \ninstance\, the classical Li-Yau / Zhong-Yang spectral-gap estimat
e holds \non all Heisenberg groups of arbitrary dimension up to a factor o
f 4.\n\nNo prior knowledge will be assumed\, and we will (hopefully) expla
in \nall of the above notions during the talk.\n
LOCATION:https://researchseminars.org/talk/GDS/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Uri Bader (Weizmann Institute of Science)
DTSTART;VALUE=DATE-TIME:20200624T111000Z
DTEND;VALUE=DATE-TIME:20200624T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/10
DESCRIPTION:Title: Tot
ally geodesic subspaces and arithemeticity phenomena in hyperbolic manifol
ds\nby Uri Bader (Weizmann Institute of Science) as part of Geometry a
nd Dynamics seminar\n\n\nAbstract\nIn this talk I will survey a well known
\, still wonderful\, connection \nbetween geometry and arithmetics and dis
cuss old and new results in \nthis topic. The starting point of the story
is Cartan's discovery \nof the correspondence between semisimple Lie group
s and symmetric \nspaces. Borel and Harish-Chandra\, following Siegel\, la
ter realized \na fantastic further relation between arithmetic subgroups o
f semisimple \nLie groups and locally symmetric space - every arithemtic g
roup gives \na locally symmetric space of finite volume. The best known ex
ample \nis the modular curve which is associated in this way with the grou
p \nSL_2(Z). This relation has a partial converse\, going under the name \
n"arithmeticity theorem"\, which was proven\, under a higher rank \nassump
tion\, by Margulis and in some rank one situations by Corlette \nand Gromo
v-Schoen. The rank one setting is related to hyperbolic \ngeometry - real\
, complex\, quaternionic or octanionic.\nThere are several open questions
regarding arithmeticity of locally \nhyperbolic manifolds of finite volume
over the real or complex fields \nand there are empirical evidences relat
ing these questions to the \ngeometry of totally geodesic submanifolds. \n
Recently\, some of these questions were solved by Margulis-Mohammadi \n(re
al hyp. 3-dim)\, Baldi-Ullmo (complex hyp.) and B-Fisher-Miller-Stover. \n
The techniques involve a mixture of ergodic theory\, algebraic groups \nth
eory and hodge theory. After surveying the above story\, explaining \nall
the terms and discussing some open questions\, I hope to have a \nlittle t
ime to say something about the proofs.\n
LOCATION:https://researchseminars.org/talk/GDS/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yusuke Kawamoto (Ecole Normale Superieure)
DTSTART;VALUE=DATE-TIME:20200701T111000Z
DTEND;VALUE=DATE-TIME:20200701T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/11
DESCRIPTION:Title: Hom
ogeneous quasimorphism\, C^0-topology and Lagrangian intersection\nby
Yusuke Kawamoto (Ecole Normale Superieure) as part of Geometry and Dynamic
s seminar\n\n\nAbstract\nThe goal of the talk is to construct a non-trivia
l homogeneous \nquasimorphism on the group of Hamiltonian diffeomorphisms
of the \n2- and 4-dimensional quadric which is continuous with respect to
both \nC^0-topology and the Hofer metric. This answers a variant of a ques
tion \nof Entov-Polterovich-Py. A comparison of spectral invariants for \n
quantum cohomology rings with different coefficient fields plays a \ncruci
al role in the proof which might be of independent interest. \nIf time per
mits\, we will see how this comparison can be used to answer \na question
of Polterovich-Wu.\n
LOCATION:https://researchseminars.org/talk/GDS/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrew Lobb (Durham University)
DTSTART;VALUE=DATE-TIME:20201028T121000Z
DTEND;VALUE=DATE-TIME:20201028T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/12
DESCRIPTION:Title: The
rectangular peg problem\nby Andrew Lobb (Durham University) as part o
f Geometry and Dynamics seminar\n\n\nAbstract\nFor any smooth Jordan curve
and rectangle in the plane\, we show that \nthere exist four points on th
e Jordan curve forming the vertices of a \nrectangle similar to the given
one. Joint work with Josh Greene.\n
LOCATION:https://researchseminars.org/talk/GDS/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laszlo Lempert (Purdue University)
DTSTART;VALUE=DATE-TIME:20201104T151000Z
DTEND;VALUE=DATE-TIME:20201104T163000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/13
DESCRIPTION:Title: On
the adjoint action of symplectomorphism groups\nby Laszlo Lempert (Pur
due University) as part of Geometry and Dynamics seminar\n\n\nAbstract\nMo
tivated by constructions in Kähler geometry\, in this talk we consider \n
a compact symplectic manifold $(X\,\\omega)$ and the group $G$ of its \nsy
mplectomorphisms. We study the action of $G$ on the Fréchet space \n$C^\\
infty(X)$ of smooth functions\, by pullback\, and describe properties of \
nconvex functions $p:C^\\infty(X)\\to\\mathbb R$ that are invariant under
this \naction.\n
LOCATION:https://researchseminars.org/talk/GDS/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bo Berndtsson (Chalmers University of Technology)
DTSTART;VALUE=DATE-TIME:20201111T121000Z
DTEND;VALUE=DATE-TIME:20201111T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/14
DESCRIPTION:Title: Com
plex integrals and Kuperberg's proof of the Bourgain-Milman theorem\nb
y Bo Berndtsson (Chalmers University of Technology) as part of Geometry an
d Dynamics seminar\n\n\nAbstract\nI will show a function version of the Bo
urgain-Milman theorem:\n$$ \\int e^{-\\phi}\\int e^{-\\phi^*}\\geq \\pi^n
$$\,\nif $\\phi$ is a symmetric convex function on $\\R^n$ and $\\phi^*$
is its \nLegendre transform. The proof is inspired by Kuperberg's proof of
the \nBourgain-Milman theorem but uses complex analytic techniques.\n
LOCATION:https://researchseminars.org/talk/GDS/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Misha Bialy (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20201118T121000Z
DTEND;VALUE=DATE-TIME:20201118T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/15
DESCRIPTION:Title: The
Birkhoff-Poritsky conjecture for centrally-symmetric billiard tables\
nby Misha Bialy (Tel Aviv University) as part of Geometry and Dynamics sem
inar\n\n\nAbstract\nIn this talk (joint work with A.E. Mironov) I shall di
scuss a recent \nproof of the Birkhoff-Poritsky conjecture for centrally-s
ymmetric \nC^2-smooth convex planar billiards. We assume that the domain
between \nthe invariant curve of 4-periodic orbits and the boundary of the
phase \ncylinder is foliated by C^0-invariant curves. Under this assumpti
on we \nprove that the billiard curve is an ellipse. The main ingredients
of \nthe proof are : (1) the non-standard generating function for convex \
nbilliards\; (2) the remarkable structure of the invariant curve \nconsist
ing of 4-periodic orbits\; and (3) the integral-geometry \napproach initia
ted for rigidity results of circular billiards. \nSurprisingly\, our resul
t yields a Hopf-type rigidity for billiard \nin ellipse.\n
LOCATION:https://researchseminars.org/talk/GDS/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vinicius G. B. Ramos (IMPA\, Brazil)
DTSTART;VALUE=DATE-TIME:20201202T151000Z
DTEND;VALUE=DATE-TIME:20201202T163000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/16
DESCRIPTION:Title: Exa
mples around the strong Viterbo conjecture\nby Vinicius G. B. Ramos (I
MPA\, Brazil) as part of Geometry and Dynamics seminar\n\n\nAbstract\nThe
Viterbo conjecture states that the ball maximizes any normalized \nsymplec
tic capacity within all convex sets in R^{2n} of a fixed volume \nand that
it is the unique maximizer. A stronger conjecture says that \nall normali
zed capacities coincide for convex sets. In joint work with \nGutt and Hut
chings\, we prove the stronger conjecture for a somewhat \ndifferent class
of 4-dimensional domains\, namely toric domains with a \ndynamically conv
ex toric boundary. In joint work with Ostrover and Sepe\, \nwe prove that
a 4-dimensional Lagrangian product which is a maximizer \nof the Hofer-Zeh
nder capacity is non-trivially symplectomorphic to a \nball giving further
evidence to the uniqueness claim of Viterbo's \nconjecture. In this talk\
, I will explain the proof of these two results.\n
LOCATION:https://researchseminars.org/talk/GDS/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Frol Zapolsky (University of Haifa)
DTSTART;VALUE=DATE-TIME:20201125T121000Z
DTEND;VALUE=DATE-TIME:20201125T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/17
DESCRIPTION:Title: Rel
ative symplectic cohomology and ideal-valued measures\nby Frol Zapolsk
y (University of Haifa) as part of Geometry and Dynamics seminar\n\n\nAbst
ract\nIn a joint work in progress together with A. Dickstein\, Y. Ganor\,
and \nL. Polterovich we prove new symplectic rigidity results. First\, we
\ncategorify the notion of a heavy subset of a symplectic manifold (due \n
to Entov-Polterovich)\, and in particular provide a simple algebraic \ncri
terion which guarantees that two heavy sets intersect. Next\, we \ntreat i
nvolutive maps defined on a symplectic manifold M\; a smooth \nmap M -> B
is involutive if pullbacks of smooth functions on B Poisson \ncommute. For
such maps we prove a refinement of Entov-Polterovich's \nnondisplaceable
fiber theorem\, as well as a symplectic Tverberg-type \ntheorem\, which ro
ughly says that each involutive map into a manifold \nof sufficiently low
dimension has a fiber which intersects a wide \nfamily of subsets of M.\n\
nAll of these results are proved using a generalized version of Gromov's \
nnotion of ideal-valued measures\, which furnish an easily digestible \nwa
y to package the relevant information. We construct such measures \nusing
relative symplectic cohomology\, an invariant recently introduced \nby U.
Varolgunes\, who also proved the Mayer-Vietoris property for it\, \non whi
ch our work relies in a crucial manner. Our main technical \ninnovation is
the relative symplectic cohomology of a pair\, whose \nconstruction is in
spired by homotopy theory.\n
LOCATION:https://researchseminars.org/talk/GDS/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lev Birbrair (Universidade Federal do Ceará\, Brazil)
DTSTART;VALUE=DATE-TIME:20201209T121000Z
DTEND;VALUE=DATE-TIME:20201209T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/18
DESCRIPTION:Title: Lip
schitz geometry of surface germs in $\\R^4$: metric knots\nby Lev Birb
rair (Universidade Federal do Ceará\, Brazil) as part of Geometry and Dyn
amics seminar\n\n\nAbstract\nA link at the origin of an isolated singulari
ty of a two-dimensional \nsemialgebraic surface in $\\R^4$ is a topologica
l knot (or link) in $S^3$. \nWe study the connection between the ambient L
ipschitz geometry of \nsemialgebraic surface germs in $\\R^4$ and the knot
theory. Namely\, for \nany knot $K$\, we construct a surface $X_K$ in $\\
R^4$ such that: $X_K$ \nhas a trivial knot at the origin\; the germs $X_K$
are outer bi-Lipschitz \nequivalent for all $K$\; two germs $X_{K}$ and $
X_{K'}$ are ambient \nbi-Lipschitz equivalent only if the knots $K$ and $K
'$ are isotopic.\n
LOCATION:https://researchseminars.org/talk/GDS/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Barak Weiss (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20201216T121000Z
DTEND;VALUE=DATE-TIME:20201216T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/19
DESCRIPTION:Title: Erg
odicity of rel foliations on the space of holomorphic one forms\nby Ba
rak Weiss (Tel Aviv University) as part of Geometry and Dynamics seminar\n
\n\nAbstract\nThe rel foliation is a foliation of the moduli space of abel
ian \ndifferentials obtained by "moving the zeroes of the one form while \
nkeeping all absolute periods fixed". It has been studied in complex \nana
lysis and dynamics under different names (isoperiodic foliation\, \nSchiff
er variation\, kernel foliation). Until recent years the question \nof its
ergodicity was wide open. Recently partial results were obtained \nby Cal
samiglia-Deroin-Francaviglia and by Hamenstadt. In our work we \ncompletel
y resolve the ergodicity question. Joint work in progress with \nJon Chaik
a and Alex Eskin\, based on a far-reaching extension of a \ncelebrated res
ult of Eskin and Mirzakhani. All relevant notions will \nbe explained in
the lecture and no prior familiarity with dynamics on \nspaces of one form
s will be assumed.\n
LOCATION:https://researchseminars.org/talk/GDS/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ood Shabtai (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20201223T121000Z
DTEND;VALUE=DATE-TIME:20201223T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/20
DESCRIPTION:Title: On
polynomials in two spectral projections of spin operators\nby Ood Shab
tai (Tel Aviv University) as part of Geometry and Dynamics seminar\n\n\nAb
stract\nWe discuss the semiclassical behavior of an arbitrary bivariate \n
polynomial evaluated on a pair of spectral projections of spin \noperators
\, and compare it with its value on a pair of random \nprojections.\n
LOCATION:https://researchseminars.org/talk/GDS/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shira Tanny (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20201230T121000Z
DTEND;VALUE=DATE-TIME:20201230T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/21
DESCRIPTION:Title: A m
ax-inequality for spectral invariants of disjointly supported Hamiltonians
\nby Shira Tanny (Tel Aviv University) as part of Geometry and Dynamic
s seminar\n\n\nAbstract\nThe relation between spectral invariants of disjo
intly supported \nHamiltonians and that of their sum was studied by Humili
ere\, Le Roux \nand Seyfaddini on aspherical manifolds. We study this rela
tion in a \nwider setting and derive applications to Polterovich's Poisson
bracket \ninvariant. This is a work in progress.\n
LOCATION:https://researchseminars.org/talk/GDS/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vincent Humilière (Sorbonne University)
DTSTART;VALUE=DATE-TIME:20210106T121000Z
DTEND;VALUE=DATE-TIME:20210106T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/22
DESCRIPTION:Title: Is
the group of compactly supported area preserving homeomorphisms of the 2-d
isk simple?\nby Vincent Humilière (Sorbonne University) as part of Ge
ometry and Dynamics seminar\n\n\nAbstract\nThis long standing open problem
has been recently solved in joint work \nwith Dan Cristofaro-Gardiner and
Sobhan Seyfaddini. I will present some \nbackground and the main ideas th
at lead to the proof. It is based on \ntools from symplectic topology and
more precisely on a theory due to \nHutchings\, called Periodic Floer Homo
logy.\n
LOCATION:https://researchseminars.org/talk/GDS/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dan Mangoubi (The Hebrew University of Jerusalem)
DTSTART;VALUE=DATE-TIME:20210113T121000Z
DTEND;VALUE=DATE-TIME:20210113T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/23
DESCRIPTION:Title: A L
ocal version of Courant's Nodal domain Theorem\nby Dan Mangoubi (The H
ebrew University of Jerusalem) as part of Geometry and Dynamics seminar\n\
n\nAbstract\nLet u_k be an eigenfunction of a vibrating string (with fixed
ends) \ncorresponding to the k-th eigenvalue. It is not difficult to show
that \nthe number of zeros of u_k is exactly k+1. Equivalently\, the numb
er of \nconnected components of the complement of $u_k=0$ is $k$.\n\nIn 19
23 Courant found that in higher dimensions (considering eigenfunctions \no
f the Laplacian on a closed Riemannian manifold M) the number of connected
\ncomponents of the open set $M\\setminus {u_k=0}$ is at most $k$.\n\nIn
1988 Donnelly and Fefferman gave a bound on the number of connected \ncomp
onents of $B\\setminus {u_k=0}$\, where $B$ is a ball in $M$. However\, \n
their estimate was not sharp (even for spherical harmonics).\n\nWe describ
e the ideas which give the sharp bound on the number of connected \ncompon
ents in a ball. The talk is based on a joint work with S. Chanillo\, \nA.
Logunov and E. Malinnikova\, with a contribution due to F. Nazarov.\n
LOCATION:https://researchseminars.org/talk/GDS/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Boaz Klartag (Weizmann Institute of Science)
DTSTART;VALUE=DATE-TIME:20210303T121000Z
DTEND;VALUE=DATE-TIME:20210303T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/24
DESCRIPTION:Title: Rig
idity of Riemannian embeddings of discrete metric spaces\nby Boaz Klar
tag (Weizmann Institute of Science) as part of Geometry and Dynamics semin
ar\n\n\nAbstract\nLet M be a complete\, connected Riemannian surface and\n
suppose that S is a discrete subset of M. What can we learn about M\nfrom
the knowledge of all distances in the surface between pairs of\npoints of
S? We prove that if the distances in S correspond to the\ndistances in a 2
-dimensional lattice\, or more generally in an\narbitrary net in R^2\, the
n M is isometric to the Euclidean plane. We\nthus find that Riemannian emb
eddings of certain discrete metric spaces\nare rather rigid. A corollary i
s that a subset of Z^3 that strictly\ncontains a two-dimensional lattice c
annot be isometrically embedded in\nany complete Riemannian surface. This
is a joint work with M. Eilat.\n
LOCATION:https://researchseminars.org/talk/GDS/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Cristofaro-Gardiner (IAS Princeton\; University of Californ
ia\, Santa Cruz)
DTSTART;VALUE=DATE-TIME:20210310T121000Z
DTEND;VALUE=DATE-TIME:20210310T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/25
DESCRIPTION:Title: The
subleading asymptotics of the ECH spectrum\nby Daniel Cristofaro-Gard
iner (IAS Princeton\; University of California\, Santa Cruz) as part of Ge
ometry and Dynamics seminar\n\n\nAbstract\nEmbedded contact homology can b
e used to associate a sequence of spectral \ninvariants\, called ECH spect
ral invariants\, to any closed three-manifold \nwith a contact form. In p
revious joint work\, we proved a “Volume Property” \nthat recovers the
volume of any such manifold from the asymptotics of its \nECH spectral in
variants. I will discuss recent work aimed at better \nunderstanding the
subleading asymptotics of this sequence. The main \nsubject of my talk wi
ll be a joint work with Nikhil Savale in which we \nprove a new bound on t
he growth rate of the subleading asymptotics. \nI will also briefly menti
on a conjecture\, due to Hutchings\, concerning \nrecovering the “contac
t Ruelle invariant” from the subleading asymptotics.\n
LOCATION:https://researchseminars.org/talk/GDS/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dmitry Faifman (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20210317T121000Z
DTEND;VALUE=DATE-TIME:20210317T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/26
DESCRIPTION:Title: Aro
und the Funk metric and its billiards\nby Dmitry Faifman (Tel Aviv Uni
versity) as part of Geometry and Dynamics seminar\n\n\nAbstract\nThe Funk
metric in the interior of a convex body is a lesser known \nrelative of th
e projectively-invariant Hilbert metric\, yet in some \nways simpler and m
ore natural. Starting with a few simple observations\, \nwe will explore s
ome Funk-inspired generalizations of well-known \nresults in the geometry
of normed spaces and Minkowski billiards\, \nsuch as Sch\\"affer's dual gi
rth conjecture and the Gutkin-Tabachnikov \nduality. I will also offer a F
unk approach to the integrability of the \nhyperbolic billiard in a conic.
Time permitting\, I will discuss the \nvolume of metric balls in Funk geo
metry\, leading to a generalization \nof the Blaschke-Santalo inequality.\
n
LOCATION:https://researchseminars.org/talk/GDS/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Peralta-Salas (ICMAT Madrid)
DTSTART;VALUE=DATE-TIME:20210324T121000Z
DTEND;VALUE=DATE-TIME:20210324T133000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/27
DESCRIPTION:Title: Tur
ing completeness and universality of steady Euler flows\nby Daniel Per
alta-Salas (ICMAT Madrid) as part of Geometry and Dynamics seminar\n\n\nAb
stract\nI will review recents results on the Turing completeness and unive
rsality \nof steady solutions to the Euler equations. In particular\, I wi
ll show \nthe existence of three-dimensional fluid flows exhibiting undeci
dable \ntrajectories and discuss other universality features such as embed
dability \nof diffeomorphisms into steady Euler states. These results are
motivated by \nTao's programme to address the blow-up problem for the Navi
er-Stokes \nequations based on the Turing completeness of the fluid flows.
This is \nbased on joint works with Robert Cardona\, Eva Miranda and Fran
cisco Presas.\n
LOCATION:https://researchseminars.org/talk/GDS/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Rosen (Ruhr-Universität Bochum)
DTSTART;VALUE=DATE-TIME:20210407T111000Z
DTEND;VALUE=DATE-TIME:20210407T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/28
DESCRIPTION:Title: Ran
dom inscribed polytopes in Non-Euclidean Geometries\nby Daniel Rosen (
Ruhr-Universität Bochum) as part of Geometry and Dynamics seminar\n\n\nAb
stract\nRandom polytopes have a long history\, going back to Sylvester's f
amous \nfour-point problem. Since then their study has become a mainstream
topic \nin convex and stochastic geometry\, with close connection to poly
topal \napproximation problems\, among other things. In this talk we will
consider \nrandom polytopes in constant curvature geometries\, and show th
at their \nvolume satisfies a central limit theorem. The proof uses Stein'
s method \nfor normal approximation\, and extends to general projective Fi
nsler metrics.\n
LOCATION:https://researchseminars.org/talk/GDS/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Melistas (University of Georgia)
DTSTART;VALUE=DATE-TIME:20210421T111000Z
DTEND;VALUE=DATE-TIME:20210421T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/29
DESCRIPTION:Title: The
Large-Scale Geometry of Overtwisted Contact Forms\nby Thomas Melistas
(University of Georgia) as part of Geometry and Dynamics seminar\n\n\nAbs
tract\nInspired by the symplectic Banach-Mazur distance\, proposed by Ostr
over\n and Polterovich in the setting of non-degenerate starshaped domains
of \nLiouville manifolds\, we define a distance on the space of contact f
orms \nsupporting a given contact structure on a closed contact manifold.
We \ncompare it to a recently defined contact Banach-Mazur distance by Ros
en \nand Zhang and we use it in order to bi-Lipschitz embed part of the \n
2-dimensional Euclidean space into the space of overtwisted contact \nform
s supporting a given contact structure on a smooth closed manifold.\n
LOCATION:https://researchseminars.org/talk/GDS/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zvi Shem-Tov (The Hebrew University of Jerusalem)
DTSTART;VALUE=DATE-TIME:20210428T111000Z
DTEND;VALUE=DATE-TIME:20210428T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/30
DESCRIPTION:Title: Con
jugation-invariant norms on arithmetic groups\nby Zvi Shem-Tov (The He
brew University of Jerusalem) as part of Geometry and Dynamics seminar\n\n
\nAbstract\nA classical theorem of Ostrowski says that every absolute valu
e on the \nfield of rational numbers\, or equivalently on the ring of inte
gers\, is \nequivalent to either the standard (real) absolute value\, or a
$p$-adic \nabsolute value\, for which the closure of the integers is comp
act. In \nthis talk we will see a non-abelian analogue of this result for
\n$SL(n\\ge3\,\\Z)$\, and related groups of arithmetic type. We will see \
na relation to the celebrated Margulis' normal subgroup theorem\, and \nde
rive rigidity results for homomorphisms into certain non-locally \ncompact
groups -- those endowed with a bi-invariant metric. We will \nalso discus
s a relation to the deep work of Nikolov-Segal on profinite \ngroups. This
is a joint work with Leonid Polterovich and Yehuda Shalom.\n
LOCATION:https://researchseminars.org/talk/GDS/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Otto van Koert (Seoul National University)
DTSTART;VALUE=DATE-TIME:20210505T111000Z
DTEND;VALUE=DATE-TIME:20210505T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/31
DESCRIPTION:Title: A g
eneralization of the Poincare-Birkhoff fixed point theorem and the restric
ted three-body problem\nby Otto van Koert (Seoul National University)
as part of Geometry and Dynamics seminar\n\n\nAbstract\nIn joint work with
Agustin Moreno\, we propose a generalization of the \nPoincare-Birkhoff f
ixed point theorem. We start with a construction of \nglobal hypersurfaces
of section in the spatial three-body problem\, describe \nsome return map
s and suggest some generalizations of the Poincare-Birkhoff \nfixed point
theorem. We use symplectic homology in the proof of our theorem.\n
LOCATION:https://researchseminars.org/talk/GDS/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Georgios Dimitroglou Rizell (Uppsala University)
DTSTART;VALUE=DATE-TIME:20210512T111000Z
DTEND;VALUE=DATE-TIME:20210512T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/32
DESCRIPTION:Title: Non
-degeneracy of Legendrians from bifurcation of contact homology\nby Ge
orgios Dimitroglou Rizell (Uppsala University) as part of Geometry and Dyn
amics seminar\n\n\nAbstract\nWe show that the invariance of Legendrian con
tact homology can be \nformulated in terms of a bifurcation analysis whose
action properties \nare continuous with respect to the oscillatory norm o
f the contact \nHamiltonian. (I.e. the barcode varies continuously with re
spect to \nthe same.) Combined with work of Rosen-Zhang this implies non-d
egeneracy \nof the Shelukhin-Chekanov-Hofer metric on the space of Legendr
ian \nembeddings. We also explain how convex surface techniques in dimensi
on \nthree can be used to prove a statement related to the converse: a \nn
on-Legendrian knot cannot be approximated by the image of a Legendrian \nk
not under a sequence of C0-converging contactomorphisms. This is joint \nw
ork with M. Sullivan.\n
LOCATION:https://researchseminars.org/talk/GDS/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Luis Diogo (Fluminense Federal University)
DTSTART;VALUE=DATE-TIME:20210519T111000Z
DTEND;VALUE=DATE-TIME:20210519T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/33
DESCRIPTION:Title: Mon
otone Lagrangians in cotangent bundles of spheres\nby Luis Diogo (Flum
inense Federal University) as part of Geometry and Dynamics seminar\n\n\nA
bstract\nAmong all Lagrangian submanifolds of a symplectic manifold\, the
class of \nmonotone Lagrangians is often very rich and nicely suited to be
ing studied \nusing pseudoholomophic curves. We find a family of monotone
Lagrangians \nin cotangent bundles of spheres with the following property:
every compact \nmonotone Lagrangian with non-trivial Floer cohomology can
not be displaced \nby a Hamiltonian diffeomorphism from at least one eleme
nt in the family. \nThis follows from the fact that the Lagrangians in the
family split-generate \nthe compact monotone Fukaya category. This is joi
nt work with Mohammed Abouzaid.\n
LOCATION:https://researchseminars.org/talk/GDS/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan David Evans (Lancaster University)
DTSTART;VALUE=DATE-TIME:20210526T111000Z
DTEND;VALUE=DATE-TIME:20210526T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/34
DESCRIPTION:Title: A L
agrangian Klein bottle you can't squeeze\nby Jonathan David Evans (Lan
caster University) as part of Geometry and Dynamics seminar\n\n\nAbstract\
nGiven a nonorientable Lagrangian surface L in a symplectic 4-manifold\, \
nhow far can you deform the symplectic form before there is no Lagrangian
\nsurface isotopic to L? I will discuss this problem in general and explai
n \nthe solution in a particular case.\n
LOCATION:https://researchseminars.org/talk/GDS/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jeff Hicks (University of Cambridge)
DTSTART;VALUE=DATE-TIME:20210602T111000Z
DTEND;VALUE=DATE-TIME:20210602T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/35
DESCRIPTION:by Jeff Hicks (University of Cambridge) as part of Geometry an
d Dynamics seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GDS/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Itamar Rosenfeld Rauch (Technion\, Haifa)
DTSTART;VALUE=DATE-TIME:20210609T111000Z
DTEND;VALUE=DATE-TIME:20210609T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/36
DESCRIPTION:by Itamar Rosenfeld Rauch (Technion\, Haifa) as part of Geomet
ry and Dynamics seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GDS/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo R.R. Alves (University of Antwerp)
DTSTART;VALUE=DATE-TIME:20210616T111000Z
DTEND;VALUE=DATE-TIME:20210616T123000Z
DTSTAMP;VALUE=DATE-TIME:20210514T205205Z
UID:GDS/37
DESCRIPTION:by Marcelo R.R. Alves (University of Antwerp) as part of Geome
try and Dynamics seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GDS/37/
END:VEVENT
END:VCALENDAR