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PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:William Riley Casper (CSUF)
DTSTART;VALUE=DATE-TIME:20210219T230000Z
DTEND;VALUE=DATE-TIME:20210220T000000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/1
DESCRIPTION:Title: Comm
uting differential and integral operators and the adelic Grassmannian\
nby William Riley Casper (CSUF) as part of Analysis and Geometry Seminar\n
\n\nAbstract\nBeginning with the work of Landau\, Pollak and Slepian in th
e 1960s on time-band limiting\, commuting pairs of integral and differenti
al operators have played a key role in signal processing\, random matrix t
heory and integrable systems. In this talk\, we will describe a close con
nection between commuting integral and differential operators and points i
n the adelic Grassmannian\, which provides a commuting pair for each self-
adjoint point in the Grassmannian. Central to this relationship is the Fo
urier algebra\, a certain algebra of differential operators isomorphic to
the algebra of differential operators on a line bundle over a rational cur
ve.\n
LOCATION:https://researchseminars.org/talk/ags/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dan Volok (Kansas State University)
DTSTART;VALUE=DATE-TIME:20210305T230000Z
DTEND;VALUE=DATE-TIME:20210306T000000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/2
DESCRIPTION:Title: Zero
s of discrete analytic polynomials\nby Dan Volok (Kansas State Univers
ity) as part of Analysis and Geometry Seminar\n\n\nAbstract\nWe shall disc
uss some basic interpolation results for discrete analytic (in the sense o
f J. Ferrand and R.J. Duffin) functions on the integer lattice in the comp
lex plane.\n
LOCATION:https://researchseminars.org/talk/ags/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mario Stipčić (University of Zagreb)
DTSTART;VALUE=DATE-TIME:20210312T230000Z
DTEND;VALUE=DATE-TIME:20210313T000000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/3
DESCRIPTION:Title: L^p
estimates for dyadic singular integral forms associated with hypergraphs a
nd for ergodic-martingale paraproducts\nby Mario Stipčić (University
of Zagreb) as part of Analysis and Geometry Seminar\n\n\nAbstract\nWe wil
l identify T(1)-type conditions and other characterizations of L^p bounded
ness of entangled multilinear singular integrals associated with hypergrap
hs. After that\, we will examine the convergence of ergodic-martingale par
aproducts in the Lebesgue spaces with respect to the range of exponents.\n
LOCATION:https://researchseminars.org/talk/ags/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Annina Iseli (UCLA)
DTSTART;VALUE=DATE-TIME:20210416T220000Z
DTEND;VALUE=DATE-TIME:20210416T230000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/5
DESCRIPTION:Title: Thur
ston maps with four postcritical points\nby Annina Iseli (UCLA) as par
t of Analysis and Geometry Seminar\n\n\nAbstract\nA Thurston map is a bran
ched covering map of the 2-sphere which is not a homeomorphism and for whi
ch every critical point has a finite orbit under iteration of the map. Fre
quently\, a Thurston map admits a description in purely combinatorial-topo
logical terms. In this context it is an interesting question whether a giv
en map can (in a suitable sense) be realized by a rational map with the sa
me combinatorics. This question was answered by Thurston in the 1980's in
his celebrated characterization of rational maps. Thurston's Theorem rough
ly says that a Thurston map is realized if and only if it does not admit a
Thurston obstruction\, which is an invariant multicurve that satisfies a
certain growth condition. However\, in practice it can be very hard to ver
ify whether a given map has no Thurston obstruction\, because\, in princip
le\, one would need to check the growth condition for infinitely many curv
es. \n \nIn this talk\, we will consider a specific family of Thurston map
s with four postcritical points that arises from Schwarz reflections on fl
apped pillows (a simple surgery of a polygonal sphere). Using a counting a
rgument\, we establish a necessary and sufficient condition for a map in t
his family to be realized by a rational map. In the last part of the talk\
, we will discuss a generalization of this result which states that\, give
n an obstructed Thurston map with four postcritical points\, one can elimi
nate obstructions by applying a so-called blowing up operation. These resu
lts are joint with M. Bonk and M. Hlushchanka.\n
LOCATION:https://researchseminars.org/talk/ags/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Trang Thi Thien Nguyen (University of South Australia)
DTSTART;VALUE=DATE-TIME:20210514T220000Z
DTEND;VALUE=DATE-TIME:20210514T230000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/6
DESCRIPTION:Title: Non-
homogeneous T(1) theorem for singular integrals on product quasimetric spa
ces\nby Trang Thi Thien Nguyen (University of South Australia) as part
of Analysis and Geometry Seminar\n\n\nAbstract\nIn the Calderón-Zygmund
Theory of singular integrals\, the T(1) theorem of David and Journé is on
e of the most celebrated theorems. It gives easily-checked criteria for a
singular integral operator T to be bounded from L^2(R^n) to L^2(R^n). Sinc
e then\, this classical result has been generalized to various settings\,
including replacing the underlying space R^n on which the operators act. \
nIn this talk\, I will present our work on generalizing the T(1) theorem\,
that brings together three attributes: 'product space'\, 'quasimetric' an
d 'non-doubling measure'. Specifically\, we prove a T(1) theorem that can
be applied to operators acting on product spaces equipped with a quasimetr
ic and an upper doubling measure\, which only satisfies an upper control o
n the size of balls.\n
LOCATION:https://researchseminars.org/talk/ags/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oumar Wone (U. of Dakar\, Senegal)
DTSTART;VALUE=DATE-TIME:20210507T220000Z
DTEND;VALUE=DATE-TIME:20210507T230000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/7
DESCRIPTION:Title: Frob
enius determinants and Toric varieties\nby Oumar Wone (U. of Dakar\, S
enegal) as part of Analysis and Geometry Seminar\n\n\nAbstract\nGiven a fi
nite group $G$ of order $n>1$ and variables $(X_g)_{g\\in G}$ the Frobeniu
s or group-determinant is by definition $\\Theta(G)((X_g)_{g\\in G}):=\\de
t((X_{gh^{-1}})_{(g\,h)\\in G\\times G})$. We associate to every Frobenius
determinant of a finite abelian group of order $n\\geqslant3$ a toric var
iety. We also study along the way its singular points and determine the nu
mber of its hyper-surfaces.\n
LOCATION:https://researchseminars.org/talk/ags/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kamal Diki (Chapman University)
DTSTART;VALUE=DATE-TIME:20210917T220000Z
DTEND;VALUE=DATE-TIME:20210917T230000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/8
DESCRIPTION:Title: An a
pproach to the Gaussian RBF kernels via Fock spaces\nby Kamal Diki (Ch
apman University) as part of Analysis and Geometry Seminar\n\n\nAbstract\n
In this talk we use methods from the Fock spaces theory in order to prove
several results on the Gaussian RBF kernels in the complex case. The latte
r is one of the most used kernels in modern machine learning kernel method
s\, and support vector machines (SVMs) classification algorithms. It turns
out that complex analysis techniques allow us to consider several notions
linked to the RBF kernels like the feature space and the feature map\, us
ing the so-called Segal-Bargmann transform. We show also that the RBF kern
els can be related to some important operators in quantum mechanics and ti
me frequency analysis\, specifically\, we prove different connections of s
uch kernels with creation\, annihilation\, Fourier\, translation\, modulat
ion and Weyl operators. A semi-group property will be proved in the case o
f Weyl operators. This is a joint work with Daniel Alpay\, Fabrizio Colomb
o and Irene Sabadini.\n
LOCATION:https://researchseminars.org/talk/ags/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Paata Ivanisvili (UC Irvine)
DTSTART;VALUE=DATE-TIME:20211112T230000Z
DTEND;VALUE=DATE-TIME:20211113T000000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/9
DESCRIPTION:Title: Lear
ning low degree functions in logarithmic number of random queries.\nby
Paata Ivanisvili (UC Irvine) as part of Analysis and Geometry Seminar\n\n
\nAbstract\nPerhaps a very basic question one asks in learning theory is a
s follows: we have an unknown function $f$ on the hypercube $\\{-1\,1\\}^n
$\, and we are allowed to query samples $(X\, f(X))$ where $X$ is uniforml
y distributed on $\\{-1\,1\\}^n$. After getting these samples $(X_1\, f(X_
1))\, ...\, (X_N\, f(X_N))$ we would like to construct a function $h$ whic
h approximates f up to an error epsilon (say in $L^2$). Of course $h$ is a
random function as it involves i.i.d. random variables $X_1\, ... \, X_N$
in its construction. Therefore\, we want to construct such $h$ which appr
oximates $f$ with probability at least ($1-\\delta$). So given parameters
epsilon\, $\\delta$ in $(0\,1)$ the goal is to minimize the number of ran
dom queries $N$. I will show that around $\\log(n)$ random queries are suf
ficient to learn bounded "low-complexity" functions. Based on joint work w
ith Alexandros Eskenazis.\n
LOCATION:https://researchseminars.org/talk/ags/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Izchak Lewkowicz (Ben-Gurion University of the Negev\, Israel)
DTSTART;VALUE=DATE-TIME:20211008T220000Z
DTEND;VALUE=DATE-TIME:20211008T230000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/10
DESCRIPTION:Title: Pas
sive Linear Time-invariant Systems - Characterization through Structure\nby Izchak Lewkowicz (Ben-Gurion University of the Negev\, Israel) as pa
rt of Analysis and Geometry Seminar\n\n\nAbstract\nPassivity is a basic ph
ysical property. We here show that the family linear time-invariant passiv
e systems may be characterized by the structure of the whole set. A refine
d description of strict dissipativity will be presented as well.\n
LOCATION:https://researchseminars.org/talk/ags/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alain Yger (Université Bordeaux)
DTSTART;VALUE=DATE-TIME:20211117T200000Z
DTEND;VALUE=DATE-TIME:20211117T210000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/12
DESCRIPTION:Title: Rev
isiting syzygies\, hence division or interpolation problems\, in terms of
residue and principal value currents\nby Alain Yger (Université Borde
aux) as part of Analysis and Geometry Seminar\n\n\nAbstract\nA joint paper
I wrote together with M. Passare and August Tsikh in 2000 (ideas there co
ming from my unfortunately last joint paper with Carlos Berenstein in 19
98) inspired since then the construction of what reveals to be a very powe
rful method to attack interpolation or division problems in Cn or Pn(C) (a
lso on Stein manifolds) by solving them through explicit closed formulae.
The beautiful idea which was introduced by Mats Andersson since 2004 consi
sts in the following: attach to any generically exact complex of hermitian
bundles over a complex analytic space both a Principal Value current and
a residue current\, the last one precisely encoding the lack of exactness
of the complex of holomorphic bundles one started with. Time has now come\
, despite the technicity inherent to such construction\, to popularize suc
h tool facing general questions such as Hilbert’s nullstellensatz\, the
surprising (and curiously not so-well known) Brian ̧con-Skoda theorem (ev
en in the polynomial setting)\, Euler-Ehrenpreis- Palamodov Fundamental Pr
inciple\, or spectral synthesis problem in (ad hoc) weighted algebras of e
ntire functions. I will try to explain this in general terms\, avoiding as
far as I can technicity by cheating a little\, and will illustrate with f
ew concrete examples the novelty and efficiency of such approach.\n
LOCATION:https://researchseminars.org/talk/ags/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ahmed Sebbar (Chapman University)
DTSTART;VALUE=DATE-TIME:20220218T223000Z
DTEND;VALUE=DATE-TIME:20220218T233000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/13
DESCRIPTION:Title: On
a question of J. P. Serre\nby Ahmed Sebbar (Chapman University) as par
t of Analysis and Geometry Seminar\n\n\nAbstract\nIn his Bourbaki talk "{\
\em Distribution asymptotique des valeurs propres des endomorphismes de Fr
obenius (d'après Abel\, Chebyshev\, Robinson\,$\\cdots)$}" of 03/31/2018\
, J.P. Serre raised the following question: \n\nLet $K\\subset \\BC$ be a
compact (infinite) set\, stable under complex conjugation and having a ca
pacity greater than one. Let $U$ be an open set containing $K$. Then there
exists a sequence of monic polynomials $P_n(X)\\in \\BZ[X]$\, ${\\rm deg}
P_n= n\,\\\; P_n^{-1}(0)\\subset U$ and \n\n\\[\\displaystyle \\lim_{n\\t
o \\infty} \\frac{1}{n} \\sum_{P_n(z)=0} \\delta_z= \\mu\n\\]\n where $\\m
u$ is the equilibrium measure of $K$ and $\\delta_z$ is the Dirac measure
at $z$. \\\\ I will present some results on this question\, obtained with
Th\\'er\\`ese Falliero(University of Avignon).\n
LOCATION:https://researchseminars.org/talk/ags/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michel Balazard (Institut de Mathématiques de Marseille)
DTSTART;VALUE=DATE-TIME:20220225T223000Z
DTEND;VALUE=DATE-TIME:20220225T233000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/14
DESCRIPTION:Title: The
criteria of Nyman and Baez-Duarte for the Riemann hypothesis\nby Mich
el Balazard (Institut de Mathématiques de Marseille) as part of Analysis
and Geometry Seminar\n\n\nAbstract\nIn his doctoral dissertation\, Nyman g
ave in 1950 a necessary and sufficient criterion for the validity of the R
iemann hypothesis\, in terms of the density of some subspace in L^2(0\,1).
In 2003\, Baez-Duarte gave a modified form of this criterion. The talk wi
ll present these two criteria\, as well as related results and questions.\
n
LOCATION:https://researchseminars.org/talk/ags/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Alpay (Chapman University)
DTSTART;VALUE=DATE-TIME:20220311T223000Z
DTEND;VALUE=DATE-TIME:20220311T233000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/15
DESCRIPTION:Title: Dis
crete analytic functions and Schur analysis\nby Daniel Alpay (Chapman
University) as part of Analysis and Geometry Seminar\n\n\nAbstract\nWe int
roduce the Schur class of functions\, discrete analytic on the integer lat
tice in the complex plane. As a special case\, we derive the explicit form
of discrete analytic Blaschke factors and solve the related basic interpo
lation problem. We define and study rational discrete analytic functions a
nd prove the existence of a coisometric realization for discrete analytic
Schur multipliers. The talk is based on collaborations with F. Colombo\, K
. Diki\, I. Sabadini and D. Volok.\n
LOCATION:https://researchseminars.org/talk/ags/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Brett Wick (Washington University in St. Louis)
DTSTART;VALUE=DATE-TIME:20220318T213000Z
DTEND;VALUE=DATE-TIME:20220318T223000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/16
DESCRIPTION:Title: Com
mutators of Calder\\'on-Zygmund Operators and Bounded Mean Oscillation (or
Factorization and Hardy Spaces)\nby Brett Wick (Washington University
in St. Louis) as part of Analysis and Geometry Seminar\n\n\nAbstract\nCal
der\\'on-Zygmund operators play an important role in partial differential
equations and complex analysis. Some problems in analysis benefit from an
understanding of the commutation between certain operators or the factori
zation of functions from natural function spaces. These topics all intera
ct when studying the commutators of Calder\\'on-Zygmund operators and mult
iplication operators. In this talk\, we will discuss some recent results
about commutators of certain Calderon-Zygmund operators and BMO spaces and
how these generate bounded operators on Lebesgue spaces. Motivations and
connections to operator theory and partial differential equations will be
provided. Versions of these results on the Heisenberg group\, pseudoconv
ex domains with $C^2$ boundary\, and other examples will be explained to s
how how the general theory carries over to many other settings. This talk
is based on joint collaborative work.\n
LOCATION:https://researchseminars.org/talk/ags/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ahmed Sebbar (Chapman University)
DTSTART;VALUE=DATE-TIME:20220304T223000Z
DTEND;VALUE=DATE-TIME:20220304T233000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/17
DESCRIPTION:Title: On
a question of J. P. Serre II\nby Ahmed Sebbar (Chapman University) as
part of Analysis and Geometry Seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ags/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:José Ramón Madrid Padilla (UCLA)
DTSTART;VALUE=DATE-TIME:20220429T210000Z
DTEND;VALUE=DATE-TIME:20220429T220000Z
DTSTAMP;VALUE=DATE-TIME:20230925T223843Z
UID:ags/18
DESCRIPTION:Title: On
classical inequalities for autocorrelations and autoconvolutions\nby J
osé Ramón Madrid Padilla (UCLA) as part of Analysis and Geometry Seminar
\n\n\nAbstract\nWe will discuss some convolution inequalities on the real
line\, the study of these problems is motivated by a classical problem in
additive combinatorics about estimating the size of Sidon sets. We will al
so discuss many related open problems. This talk will be accessible for a
broad audience.\n
LOCATION:https://researchseminars.org/talk/ags/18/
END:VEVENT
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