BEGIN:VCALENDAR
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PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201106T130000Z
DTEND:20201106T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/1
DESCRIPTION:Title: Operator algebraic introduction to non-local games\nby I. G. Todoro
v (QUB & U. Delaware) as part of Functional analysis and operator algebras
in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201113T130000Z
DTEND:20201113T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/2
DESCRIPTION:Title: Operator algebraic introduction to non-local games (2nd talk)\nby I
. G. Todorov (QUB & U. Delaware) as part of Functional analysis and operat
or algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201120T130000Z
DTEND:20201120T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/3
DESCRIPTION:Title: Operator algebraic introduction to non-local games (3rd talk)\nby I
. G. Todorov (QUB & U. Delaware) as part of Functional analysis and operat
or algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201127T130000Z
DTEND:20201127T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/4
DESCRIPTION:Title: Operator algebraic introduction to non-local games (4th talk)\nby I
. G. Todorov (QUB & U. Delaware) as part of Functional analysis and operat
or algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Giannopoulos (NKUA)
DTSTART:20201204T130000Z
DTEND:20201204T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/5
DESCRIPTION:Title: Isoperimetric constants of metric probability spaces\nby A. Giannop
oulos (NKUA) as part of Functional analysis and operator algebras in Athen
s\n\n\nAbstract\nIn this first talk we shall introduce four isoperimetric\
nconstants (the Cheeger constant\, the Poincare constant\, the exponential
concentration\nconstant and the first moment concentration constant) asso
ciated with a Borel\nprobability measure on R^n and discuss their relation
. We shall review classical\nresults of Maz'ya\, Cheeger\, Gromov\, V. Mil
man\, Buser\, Ledoux and others\, as well as\na theorem of E. Milman which
establishes the equivalence of all four constants in the\nlog-concave set
ting.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Giannopoulos (NKUA)
DTSTART:20201211T130000Z
DTEND:20201211T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/6
DESCRIPTION:Title: Isoperimetric constants of metric probability spaces (2nd talk)\nby
A. Giannopoulos (NKUA) as part of Functional analysis and operator algebr
as in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kenneth R. Davidson (University of Waterloo)
DTSTART:20201218T140000Z
DTEND:20201218T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/7
DESCRIPTION:Title: Noncommutative Choquet theory (NOTE TIME)\nby Kenneth R. Davidson (
University of Waterloo) as part of Functional analysis and operator algebr
as in Athens\n\n\nAbstract\nWe introduce a new framework for noncommutativ
e convexity. We develop a\nnoncommutative Choquet theory and prove an anal
ogue of the Choquet-Bishop-de Leeuw theorem.\nThis is joint work with Matt
hew Kennedy.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Katavolos (NKUA)
DTSTART:20210108T140000Z
DTEND:20210108T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/8
DESCRIPTION:Title: Harmonic Operators and Crossed Products\nby A. Katavolos (NKUA) as
part of Functional analysis and operator algebras in Athens\n\n\nAbstract\
nWe study the space of harmonic operators for a probability measure μ (o
r a family of measures) on a group G\, as a “quantization” of μ-harm
onic (or jointly harmonic) functions on G. This leads to two different not
ions of crossed products of operator spaces by actions of G which coincide
when G satisfies a certain approximation property. The corresponding (dua
l) notions of crossed products of (co-) actions by the von Neumann algebra
of G always coincide.This is a survey of joint work with M. Anoussis and
I.G. Todorov\, and of recent work by D. Andreou.\n \n\nFor Zoom meeting c
oordinates and additional information see the seminar webpage\n\nhttp://us
ers.uoa.gr/~akatavol/anak2021.html#1\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:P. Dodos (NKUA)
DTSTART:20210115T140000Z
DTEND:20210115T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/9
DESCRIPTION:Title: High-dimensional random arrays. Structural decompositions and concentra
tion.\nby P. Dodos (NKUA) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nA d-dimensional random array is a stocha
stic process indexed by theset of all d-element subsets of a set I. We sha
ll discuss the structure of finite\,high-dimensional random arrays\, with
finite valued entries (e.g.\, boolean) whose distribution is suffici
ently symmetric. \nSpecifically\, we shall focus on the following interrel
ated problems: concentration and distributional decompositions.\nThis
is joint work with Kostas Tyros and Petros Valettas\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:P. Dodos (NKUA)
DTSTART:20210122T140000Z
DTEND:20210122T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/10
DESCRIPTION:Title: High-dimensional random arrays. Structural decompositions and concentr
ation. (2nd talk)\nby P. Dodos (NKUA) as part of Functional analysis a
nd operator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210129T130000Z
DTEND:20210129T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/11
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210205T130000Z
DTEND:20210205T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/12
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210212T140000Z
DTEND:20210212T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/13
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Siskakis (A.U. Thessaloniki)
DTSTART:20210219T140000Z
DTEND:20210219T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/14
DESCRIPTION:Title: The Hilbert matrix and its continuous version\nby A. Siskakis (A.U
. Thessaloniki) as part of Functional analysis and operator algebras in At
hens\n\n\nAbstract\nWe will recount some known results on the discrete Hil
bert matrix as an operator onspaces of analytic functions\, and will consi
der the continuous version of the operator on suitablefunction spaces. For
the latter\, a theorem from Abstract Harmonic Analysis will be used todet
ermine its norm and spectrum.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Ghandehari (U. Delaware)
DTSTART:20210226T140000Z
DTEND:20210226T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/15
DESCRIPTION:Title: Fourier algebras of the group of R-affine transformations and a dual c
onvolution.\nby M. Ghandehari (U. Delaware) as part of Functional anal
ysis and operator algebras in Athens\n\n\nAbstract\nA major trend in Non-c
ommutative Harmonic Analysis is to investigate function spaces related toF
ourier analysis (and representation theory) of non-abelian groups. The Fo
urier algebra\, which is associatedwith the left regular representation o
f the ambient group\, is an important example of such function spaces. Th
isfunction algebra encodes the properties of the group in various ways\; f
or instance the existence of derivationson this algebra translates into in
formation about the commutativity of the group itself.In this talk\, we in
vestigate the Fourier algebra of the group ofR-affine transformations. In
particular\, wediscuss the non-commutative Fourier transform for this gro
up\, and provide an explicit formula for the convolutionproduct on the “
dual side” of this transform. As an application of this new dual convol
ution product\, we showan easy dual formulation for (the only known) symme
tric derivative on the Fourier algebra of the group.This talk is mainly ba
sed on joint articles with Y. Choi.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. G. Katsoulis (ECU\, USA)
DTSTART:20210305T140000Z
DTEND:20210305T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/16
DESCRIPTION:Title: Co-universal C*-algebras for product systems\nby E. G. Katsoulis (
ECU\, USA) as part of Functional analysis and operator algebras in Athens\
n\n\nAbstract\nIn these talks we will present parts of the recent paper of
A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with X. Li. The emphas
is is on the interaction between selfadjoint and nonselfadjoint operator a
lgebra theory with applications to current problems in C*-algebra theory.
Significant effort will be made in carefully reviewing preliminaries\, inc
luding basic facts from the theory of C*-envelopes and product systems.\n\
nContinuous product systems were introduced and studied by Arveson in the
late 1980s. The study of their discrete analogues started with the work of
Dinh in the 1990s and it was formalized by Fowler in 2002. Discrete produ
ct systems are semigroup versions of C*-correspondences\, that allow for a
joint study of many fundamental C*-algebras\, including those which come
from C*-correspondences\, higher rank graphs and elsewhere.\n\nKatsura’s
covariant relations have been proven to give the correct Cuntz-type C*-al
gebra for a C*-correspondence X. One of the great advantages Katsura’s C
untz-Pimsner C*-algebra is its co-universality for the class of gauge-comp
atible injective representations of X. In the late 2000s Carlsen-Larsen-Si
ms-Vittadello raised the question of the existence of such a co-universal
object in the context of product systems. In their work\, Carlsen-Larsen-S
ims-Vittadello provided an affirmative answer for quasi-lattices\, with ad
ditional injectivity assumptions on X. The general case has remained open
and will be addressed in these talks using tools from non-selfadjoint oper
ator algebra theory.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. G. Katsoulis (ECU\, USA)
DTSTART:20210312T140000Z
DTEND:20210312T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/17
DESCRIPTION:Title: Co-universal C*-algebras for product systems\, 2nd talk\nby E. G.
Katsoulis (ECU\, USA) as part of Functional analysis and operator algebras
in Athens\n\n\nAbstract\nIn these talks we will present parts of the rece
nt paper of A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with X. Li.
The emphasis is on the interaction between selfadjoint and nonselfadjoint
operator algebra theory with applications to current problems in C*-algeb
ra theory. Significant effort will be made in carefully reviewing prelimin
aries\, including basic facts from the theory of C*-envelopes and product
systems.\n\nContinuous product systems were introduced and studied by Arve
son in the late 1980s. The study of their discrete analogues started with
the work of Dinh in the 1990s and it was formalized by Fowler in 2002. Dis
crete product systems are semigroup versions of C*-correspondences\, that
allow for a joint study of many fundamental C*-algebras\, including those
which come from C*-correspondences\, higher rank graphs and elsewhere.\n\n
Katsura’s covariant relations have been proven to give the correct Cuntz
-type C*-algebra for a C*-correspondence X. One of the great advantages Ka
tsura’s Cuntz-Pimsner C*-algebra is its co-universality for the class of
gauge-compatible injective representations of X. In the late 2000s Carlse
n-Larsen-Sims-Vittadello raised the question of the existence of such a co
-universal object in the context of product systems. In their work\, Carls
en-Larsen-Sims-Vittadello provided an affirmative answer for quasi-lattice
s\, with additional injectivity assumptions on X. The general case has rem
ained open and will be addressed in these talks using tools from non-selfa
djoint operator algebra theory.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20210319T140000Z
DTEND:20210319T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/18
DESCRIPTION:Title: Co-universal C*-algebras for product systems\, 3rd talk\nby E. Ka
kariadis (Newcastle\, UK) as part of Functional analysis and operator alge
bras in Athens\n\n\nAbstract\nIn these talks we will present parts of the
recent paper of A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with X.
Li. The emphasis is on the interaction between selfadjoint and nonselfadj
oint operator algebra theory with applications to current problems in C*-a
lgebra theory. Significant effort will be made in carefully reviewing prel
iminaries\, including basic facts from the theory of C*-envelopes and prod
uct systems.\n\nContinuous product systems were introduced and studied by
Arveson in the late 1980s. The study of their discrete analogues started w
ith the work of Dinh in the 1990s and it was formalized by Fowler in 2002.
Discrete product systems are semigroup versions of C*-correspondences\, t
hat allow for a joint study of many fundamental C*-algebras\, including th
ose which come from C*-correspondences\, higher rank graphs and elsewhere.
\n\nKatsura’s covariant relations have been proven to give the correct C
untz-type C*-algebra for a C*-correspondence X. One of the great advantage
s Katsura’s Cuntz-Pimsner C*-algebra is its co-universality for the clas
s of gauge-compatible injective representations of X. In the late 2000s Ca
rlsen-Larsen-Sims-Vittadello raised the question of the existence of such
a co-universal object in the context of product systems. In their work\, C
arlsen-Larsen-Sims-Vittadello provided an affirmative answer for quasi-lat
tices\, with additional injectivity assumptions on X. The general case has
remained open and will be addressed in these talks using tools from non-s
elfadjoint operator algebra theory.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20210326T140000Z
DTEND:20210326T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/19
DESCRIPTION:Title: Co-universal C*-algebras for product systems\, 4th talk\nby E. Ka
kariadis (Newcastle\, UK) as part of Functional analysis and operator alge
bras in Athens\n\n\nAbstract\nIn these talks we will present parts of the
recent paper of A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with X.
Li. The emphasis is on the interaction between selfadjoint and nonselfadj
oint operator algebra theory with applications to current problems in C*-a
lgebra theory. Significant effort will be made in carefully reviewing prel
iminaries\, including basic facts from the theory of C*-envelopes and prod
uct systems.\n\nContinuous product systems were introduced and studied by
Arveson in the late 1980s. The study of their discrete analogues started w
ith the work of Dinh in the 1990s and it was formalized by Fowler in 2002.
Discrete product systems are semigroup versions of C*-correspondences\, t
hat allow for a joint study of many fundamental C*-algebras\, including th
ose which come from C*-correspondences\, higher rank graphs and elsewhere.
\n\nKatsura’s covariant relations have been proven to give the correct C
untz-type C*-algebra for a C*-correspondence X. One of the great advantage
s Katsura’s Cuntz-Pimsner C*-algebra is its co-universality for the clas
s of gauge-compatible injective representations of X. In the late 2000s Ca
rlsen-Larsen-Sims-Vittadello raised the question of the existence of such
a co-universal object in the context of product systems. In their work\, C
arlsen-Larsen-Sims-Vittadello provided an affirmative answer for quasi-lat
tices\, with additional injectivity assumptions on X. The general case has
remained open and will be addressed in these talks using tools from non-s
elfadjoint operator algebra theory.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo Laca (University of Victoria\, Canada)
DTSTART:20210402T130000Z
DTEND:20210402T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/20
DESCRIPTION:Title: C*-algebras generated by isometries: 60 years and counting\nby Mar
celo Laca (University of Victoria\, Canada) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nThe first talk will be a (
necessarily biased and partial) survey of the history of\nC*-algebras gene
rated by isometries on Hilbert space. I will begin by recalling\nclassical
theorems of Coburn\, Douglas\, and Cuntz from the 1960’s and 1970’s\n
and then discuss their proofs. Douglas’ and Cuntz’s approaches already
indicate\, \nin an implicit way\, that semigroup crossed products play a
central role.\nThis was not formalized until the late 1980’s and early 1
990’s when Murphy\,\nStacey\, Nica\, and then Raeburn and I developed an
explicit semigroup crossed\nproduct approach for Toeplitz algebras\, focu
sing on a covariance condition that\nworks quite well for quasi-lattice or
dered groups. I will elaborate a bit on this\napproach and show how it wor
ks in a few examples. I will finish by discussing\nbriefly the semigroup C
*-algebra C^*_s(P) introduced by Xin Li in the 2010’s \nusing constructi
ble right ideals to generalize Nica’s covariance condition\, and will\nf
inish by giving some non quasi-lattice ordered examples from number theory
.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo Laca (University of Victoria\, Canada)
DTSTART:20210409T130000Z
DTEND:20210409T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/21
DESCRIPTION:Title: C*-algebras generated by isometries: 60 years and counting\nby Mar
celo Laca (University of Victoria\, Canada) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nThe second talk will be on
my joint work with Sehnem from the 2020’s about\na universal Toeplitz a
lgebra T_u(P) defined via generators and relations whenever\nP is a submon
oid of a group G. The C*-algebra T_u(P) coincides with Xin Li’s\nC_s^∗
(P) when the semigroup satisfies his independence condition but behaves\na
s expected also when independence fails\; for example\, it is isomorphic t
o the\nC*-algebra of the left regular representation when the group G is a
menable and\nalso in many nonamenable situations. I will give a characteri
zation of faithful\nrepresentations and a uniqueness theorem for these uni
versal Toeplitz algebras\,\nwhich are new results even for right LCM monoi
ds. Time permitting I will also\ndiscuss how Sehnem’s covariance algebra
of a product system leads to a full\nboundary quotient of T_u(P)\, genera
lizing the boundary relations of quasi-lattice\norders introduced by Crisp
and myself in the 2000’s.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Kennedy (University of Waterloo\, Canada)
DTSTART:20210416T130000Z
DTEND:20210416T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/22
DESCRIPTION:Title: Amenability\, proximality and higher order syndeticity\nby Matthew
Kennedy (University of Waterloo\, Canada) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nI will present new descript
ions of some universal flows associated to a discrete group\, obtained usi
ng what we view as a kind of “topological Furstenberg correspondence.”
The descriptions are algebraic and relatively concrete\, involving subse
ts of the group satisfying a higher order notion of syndeticity. We utiliz
e them to establish new necessary and sufficient conditions for strong ame
nability and amenability. Furthermore\, utilizing similar techniques\, we
obtain a characterization of “dense orbit sets\,” answering a question
of Glasner\, Tsankov\, Weiss and Zucker. Throughout the talk\, I will dis
cuss connections to operator algebras. \nThis is joint work with Sven Raum
and Guy Salomon.\n\nFor Zoom meeting coordinates\nand additional informat
ion see the seminar webpage\n\nhttp://users.uoa.gr/~akatavol/anak2021.html
#1\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xin Li (University of Glasgow\, UK)
DTSTART:20210423T130000Z
DTEND:20210423T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/23
DESCRIPTION:Title: Semigroup C*-algebras and their K-theory\nby Xin Li (University of
Glasgow\, UK) as part of Functional analysis and operator algebras in Ath
ens\n\n\nAbstract\nI will report on developments in semigroup C*-algebras\
, with a particular focus on examples\, structural properties and classifi
cation results. A key ingredient is given by a K-theory formula\, which ha
s been generalized recently\, as we will discuss.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Daws (University of Central Lancashire\, UK)
DTSTART:20210514T130000Z
DTEND:20210514T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/24
DESCRIPTION:Title: Purely infinite algebras and ultrapowers\nby Matthew Daws (Univers
ity of Central Lancashire\, UK) as part of Functional analysis and operato
r algebras in Athens\n\n\nAbstract\nI will discuss what it means for a Ban
ach Algebra to be purely infinite (with a brief nod towards the important
class of purely infinite C*-algebras). The ultrapower construction is an i
nteresting\nway to convert "approximate" relations into exact ones\, and h
as\nimportant links to (continuous) model theory. We ask the question:\nwh
en does a purely infinite Banach algebra have purely infinite\nultrapowers
? This is equivalent to having a "quantified" version of\nbeing purely inf
inite\, where one has norm control over certain\nchoices. This is always s
o for C*-algebras\, but we present some\nexamples of Banach algebras where
this works\, and where it doesn't.\nOur examples are rather "natural"\, i
n the sense that we don't just\nfiddle with the norm of elements. This is
joint work with Bence\nHorvath.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sophie Grivaux (Université de Lille\, FR)
DTSTART:20210521T130000Z
DTEND:20210521T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/25
DESCRIPTION:Title: Typical properties of contractions on l_p spaces\nby Sophie Grivau
x (Université de Lille\, FR) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nGiven a separable Banach space $X$ of in
finite dimension\, one can consider on the space $\\mathcal{B}(X)$ of boun
ded linear operators on $X$ several \nnatural topologies which turn the cl
osed unit ball $B_1(X)=\\{T\\in\\mathcal{B}(X)\;||T||\\le 1\\}$ into a Pol
ish space\, i.e. a separable and completely metrizable space. \n\nIn this
talk\, I will present some results concerning typical properties in the Ba
ire Category sense of operators of $B_1(X)$ for these \ntopologies when $X
$ is a $\\ell_p$-space\, our main interest being to determine whether typi
cal contractions on these spaces have a non-trivial invariant subspace or
not. \n\nThe talk is based on joint work with \\'Etienne Matheron and Quen
tin Menet.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Sherman (University of Virginia\, USA)
DTSTART:20210528T130000Z
DTEND:20210528T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/26
DESCRIPTION:Title: A quantization of coarse structures and uniform Roe algebras\nby D
avid Sherman (University of Virginia\, USA) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nA coarse structure is a wa
y of talking about "large-scale" properties. It is encoded in a family o
f relations that often\, but not always\, come from a metric. A coarse str
ucture naturally gives rise to Hilbert space operators that in turn genera
te a so-called uniform Roe algebra.\nIn ongoing work with Bruno Braga and
Joe Eisner\, we use ideas of Weaver to construct "quantum" coarse structur
es and uniform Roe algebras in which the underlying set is replaced with a
n arbitrary represented von Neumann algebra. The general theory immediat
ely applies to quantum metrics (suitably defined)\, but it is much richer.
We explain another source of examples based on measure instead of metric\
, leading to a large and easy-to-understand class of new C*-algebras.\nI w
ill present the big picture: where uniform Roe algebras come from\, how We
aver's framework facilitates our definitions. I will focus on a few illust
rative examples and will not assume any familiarity with coarse structures
or von Neumann algebras.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle\, UK)
DTSTART:20220211T150000Z
DTEND:20220211T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/27
DESCRIPTION:Title: Rigidity of analytic operator algebras\nby E.T.A. Kakariadis (Newc
astle\, UK) as part of Functional analysis and operator algebras in Athens
\n\n\nAbstract\nAbstract: In the past 20 years\, nonselfadjoint algebras h
ave been proven to\nprovide complete invariants for geometric structures.
This follows from a\ncombination of techniques from Complex Analysis\, Fun
ctional Analysis and\nAlgebra. In this talk I will survey on rigidity resu
lts for analytic operator\nalgebras related to subproduct systems and semi
groups. In some cases\, this is in\nstark contrast to what happens with C*
-algebras.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle\, UK)
DTSTART:20220218T150000Z
DTEND:20220218T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/28
DESCRIPTION:Title: Rigidity of analytic operator algebras (2nd talk)\nby E.T.A. Kakar
iadis (Newcastle\, UK) as part of Functional analysis and operator algebra
s in Athens\n\n\nAbstract\nAbstract: In the past 20 years\, nonselfadjoint
algebras have been proven to\nprovide complete invariants for geometric s
tructures. This follows from a\ncombination of techniques from Complex Ana
lysis\, Functional Analysis and\nAlgebra. In this talk I will survey on ri
gidity results for analytic operator\nalgebras related to subproduct syste
ms and semigroups. In some cases\, this is in\nstark contrast to what happ
ens with C*-algebras.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. Spronk (Waterloo\, Canada)
DTSTART:20220225T150000Z
DTEND:20220225T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/29
DESCRIPTION:Title: Topologies\, idempotents and ideals\nby N. Spronk (Waterloo\, Cana
da) as part of Functional analysis and operator algebras in Athens\n\n\nAb
stract\nLet $G$ be a topological group. I wish to exhibit a bijection betw
een (i) a certain class of weakly almost periodic topologies\, (ii) idempo
tents in the weakly almost periodic compactification of $G$\, and (iii) ce
rtain ideals of the algebra of weakly almost periodic functions. This has
applications to decomposing weakly almost periodic representations on Bana
ch spaces\, generalizing results which go back to many authors.\n\nMoving
to unitary representations\, I will develop the Fourier-Stieltjes algebra
$B(G)$ of $G$\, and give the analogous result there. As an application\, I
show that for a locally compact connected group\, operator amenability of
$B(G)$ implies that $G$ is compact\, partially resolving a problem of int
erest for 25 years.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D. Andreou (NKUA)
DTSTART:20220304T150000Z
DTEND:20220304T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/30
DESCRIPTION:Title: Crossed products of operator spaces and approximation properties\n
by D. Andreou (NKUA) as part of Functional analysis and operator algebras
in Athens\n\n\nAbstract\nWe will discuss two notions of crossed product fo
r group actions as\nwell as coactions on dual operator spaces\, which gene
ralize the usual von\nNeumann algebra crossed product. The goal is to desc
ribe certain group\napproximation conditions\, such as the Haagerup-Kraus
approximation property\nand Ditkin's condition at infinity\, through prope
rties of the associated crossed\nproduct functors.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220422T140000Z
DTEND:20220422T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/31
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and operator al
gebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220429T140000Z
DTEND:20220429T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/32
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and operator al
gebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefaan Vaes (KU Leuven)
DTSTART:20220506T140000Z
DTEND:20220506T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/33
DESCRIPTION:Title: W$^*$-rigidity paradigms for embeddings of II$_1$ factors\nby Stef
aan Vaes (KU Leuven) as part of Functional analysis and operator algebras
in Athens\n\n\nAbstract\nI will report on a joint work with Sorin Popa in
which we undertake a systematic study on the following question: when can
a given II$_1$ factor be embedded into another given II$_1$ factor? More g
enerally\, we say that a II$_1$ factor $M$ stably embeds into a II$_1$ fac
tor $N$ if $M$ may be realized as a subfactor of an amplification of $N$\,
not necessarily of finite index. We provide families of II$_1$ factors th
at are mutually non stably embeddable\, as well as families that are mutua
lly embeddable\, yet nonisomorphic. We prove that the preorder relation of
stable embeddability is as complicated as it can be since it contains any
partially ordered set. We also obtain numerous computations of invariants
of II$_1$ factors\, including descriptions of all stable self embeddings\
, outer automorphism groups\, etc.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tr. Russell (U.S.M.A. Westpoint)
DTSTART:20220415T140000Z
DTEND:20220415T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/34
DESCRIPTION:Title: An operator system approach to quantum correlations\nby Tr. Russel
l (U.S.M.A. Westpoint) as part of Functional analysis and operator algebra
s in Athens\n\n\nAbstract\nIn this talk\, I will explain a novel approach
to Tsirelson's problem\nusing the theory of operator systems. Tsirelson's
problem relates to whether the\ncommuting operator model of quantum mechan
ics produces different statistics\nthan the tensor product model of quantu
m mechanics in non-local measurement\nscenarios. These questions have been
shown to be equivalent to Connes'\nembedding problem from the theory of V
on Neumann algebras. After\ntremendous effort by physicists\, mathematicia
ns\, and computer scientists\,\nTsirelson's problem was finally resolved i
n a recent paper. Nevertheless\,\ninterest in understanding Tsirelson's pr
oblem in greater detail remains. After\nexploring some background in the t
heory of operator systems\, I will explain\nhow to characterize quantum co
rrelations using only abstract operator system\ntheory\, building upon exi
sting C*-algebraic and operator theoretic\ncharacterizations in the litera
ture. This new characterization yields an\nequivalent restatement of Tsire
lson's problem in the language of abstract\noperator systems.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Pisier (Texas A&M\, USA\, Sorbonne Universite\, Fr.)
DTSTART:20220311T150000Z
DTEND:20220311T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/35
DESCRIPTION:Title: The lifting property for C* algebras\nby G. Pisier (Texas A&M\, US
A\, Sorbonne Universite\, Fr.) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nWe give several characterizations of th
e lifting property (LP in short) using the maximal tensor product for C* -
algebras. The class of algebras with LP includes all nuclear C*-algebras b
ut also the full C*-algebras of free groups. The local version of the LP (
LLP in short) will be discussed in connection with the problem whether the
local LP implies the global LP in the separable case.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:O.M. Shalit (Technion\, Haifa)
DTSTART:20220513T140000Z
DTEND:20220513T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/36
DESCRIPTION:Title: CP-semigroups and dilations\, subproduct systems and superproduct syst
ems\nby O.M. Shalit (Technion\, Haifa) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nIn a joint work with Michae
l Skeide\, we introduce a framework for studying dilations of semigroups o
f completely positive maps on C*-algebras. The heart of our method is the
systematic use of families of Hilbert C*-correspondences that behave nicel
y with respect to tensor products: these are product systems\, subproduct
systems and superproduct systems. Although we developed our tools with the
goal of understanding the multi-parameter case\, they also lead to new re
sults even in the well studied one parameter case. In my talk I will give
a broad outline of our work.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D. Pitts (University of Nebraska-Lincoln)
DTSTART:20220408T140000Z
DTEND:20220408T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/37
DESCRIPTION:Title: Normalizers and Approximate Units for Inclusions of C*-Algebras\nb
y D. Pitts (University of Nebraska-Lincoln) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nConsider {\\it inclusions}
\, which are pairs of $C^*$-algebras $(C\,D)$ with $D$ an abelian subalgeb
ra of $C$. An element $v\\in C$ {\\it normalizes} $D$ if $v^*D v \\cup v
Dv^* \\subseteq D$. The inclusion $(C\,D)$ is {\\it regular} when the lin
ear span of the normalizers is dense in $C$ and is {\\it singular} when ev
ery normalizer belongs to $D$.\n\nI will prove a commutation result for He
rmitian normalizers\, then discuss some consequences of this result relat
ed to familiar constructions. Sample consequence:\nwhen $D$ is a regular
MASA in $C$\, every approximate unit for $D$ is an approximate unit for $C
$\; this leads to simplifiation of the notions of Cartan MASA and $C^*$-
diagonal in the non-unital setting.\n\nThe inclusion $(C\,D)$ is {\\it int
ermediate} to the regular MASA inclusion $(B\,D)$ if $D\\subseteq C\\subse
teq B$.\nI will give examples showing some singular MASA inclusions are in
termediate to regular MASA inclusions\, but others are not\, and will dis
cuss the fact that when $\\mathcal H$ is a separable\, infinite dimensiona
l Hilbert space\, no MASA inclusion of the form $(\\mathcal B(\\mathcal H)
\, D)$ is intermediate to a regular MASA inclusion.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Gillaspy (U. Montana\, USA)
DTSTART:20220527T140000Z
DTEND:20220527T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/38
DESCRIPTION:Title: Cartan subalgebras in groupoid C*-algebras\nby E. Gillaspy (U. Mon
tana\, USA) as part of Functional analysis and operator algebras in Athens
\n\n\nAbstract\nBuilding on earlier work of Kumjian\, Renault proved in 20
08 that a C*-algebra $A$ has a Cartan subalgebra $B$ if and only if there
is a topologically principal groupoid $W$ whose twisted C*-algebra $C^*(W\
; S)$ is isomorphic to $A$. In fact\, $W$ (the Weyl groupoid of the Cartan
pair $(B\, A)$) can be constructed from $A$ and $B$. However\, a groupoi
d $W$ does not have to be topologically principal in order to construct $C
^*(W\; S)$. Do those more general groupoid C*-algebras have Cartan subalge
bras\, and if so\, what is the relationship between the Weyl groupoid and
the original groupoid?\n\n \n\nIn joint work with A. Duwenig\, R. Norton\,
S. Reznikoff\, and S. Wright\, we identified situations when a subgroupoi
d $S$ of a non-principal groupoid $G$ will give rise to a Cartan subalgebr
a $B = C^*(S)$ of $A = C^*(G)$. Subsequent work\, joint with A. Duwenig a
nd R. Norton\, revealed that in this case\, the Weyl groupoid $W$ of the p
air $(B\, A)$ is a semidirect product: $W = G/S \\ltimes \\widehat{S}$. W
e also describe the Weyl twist explicitly in the situation where there is
a continuous section $G/S \\to G$. Furthermore\, ongoing joint work with J
.H. Brown has established that the description of the Weyl groupoid is val
id even in the more general setting of $\\Gamma$-Cartan pairs.\n\n \n\nIf
you're still mostly lost after reading this abstract\, never fear! The tal
k will not assume familiarity with groupoids\, their C*-algebras\, or Cart
an subalgebras for C*-algebras\, and should (I hope) be more comprehensibl
e.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Brannan (U. Waterloo\, Canada)
DTSTART:20220520T130000Z
DTEND:20220520T143000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/39
DESCRIPTION:Title: Quantum path spaces\, correspondences\, and quantum Cuntz-Krieger alge
bras NOTE UNUSUAL TIME\nby M. Brannan (U. Waterloo\, Canada) as part o
f Functional analysis and operator algebras in Athens\n\n\nAbstract\nIn re
cent years there has been a significant interest in studying generalizatio
ns of graphs within the framework of noncommutative geometry. Such object
s are called quantum graphs. In this talk I will explain what a quantum g
raph is\, and also introduce quantum Cuntz-Krieger (QCK) algebras\, which
are a class of universal C*-algebras associated to quantum graphs previous
ly introduced by Eifler\, Voigt\, Weber and the speaker. \nAs the name
suggests\, QCK algebras generalize Cuntz-Krieger algebras of ordinary grap
hs\, but they turn out to be very hard to understand. In this talk I will
explain some attempts to better understand QCK algebras by considering qua
ntum analogues of graph correspondences and their associated Cuntz-Pimsner
algebras\, as well as infinite quantum path spaces and their associated E
xel crossed products. \nThis is based on joint work with Mitch Hamidi\, L
ara Ismert\, Brent Nelson and Mateusz Wasilewski.\n\nNOTE UNUSUAL TIME\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Ghandehari (U. Delaware)
DTSTART:20220318T150000Z
DTEND:20220318T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/40
DESCRIPTION:Title: Meaningful decay behavior of higher dimensional continuous wavelet tra
nsforms\nby M. Ghandehari (U. Delaware) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nThe wavefront set of a tem
pered distribution $u$ is the set of points $t\\in{\\mathbb R}^n$ and dire
ctions $\\xi$ in the sphere $S^{n-1}$ along which $u$ is not smooth at $t$
. In the recent years\, certain wavelet-type transformations (for example
the curvelet or shearlet transformation) have gained considerable attentio
n\, due to their potential for identifying the wavefront set of a signal b
y inspecting the decay rate of the corresponding transformation coefficien
ts. \n\nRecently\, many efforts have been made aiming to generalize the ab
ove characterization for higher dimensional cases. Higher dimensional wave
let transforms are constructed using square-integrable representations of
${\\mathbb R}^n\\rtimes H$ where $H$ can be any suitably chosen dilation g
roup. In this talk\, we consider the problem of characterizing the Sobolev
wavefront set of a distribution for a higher-dimensional wavelet transfor
m in two important cases where: 1) the mother wavelet is compactly support
ed\, and 2) the mother wavelet has compactly supported Fourier transform.
\n\nThis talk is based on an ongoing joint project with Hartmut Fuhr.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220325T150000Z
DTEND:20220325T163000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/41
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and operator al
gebras in Athens\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Ioana (UCSD\, USA)
DTSTART:20220401T140000Z
DTEND:20220401T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/42
DESCRIPTION:Title: Wreath-like product groups and rigidity of their von Neumann algebras<
/a>\nby A. Ioana (UCSD\, USA) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nIn this talk\, I will introduce a new cl
ass of groups\, called wreath-like products. These groups are close relati
ves of the classical wreath products and arise naturally in the context of
group theoretic Dehn filling. Unlike ordinary wreath products\, many wrea
th-like products have Kazhdan's property (T). I will present several new r
igidity results for von Neumann algebras of wreath-like products with prop
erty (T). In particular\, we obtain the first examples of property (T) gr
oups $G$ which are W*-superrigid\, in the sense that the group von Neumann
algebra $\\text{L}(G)$ remembers the isomorphism class of $G$. We also c
ompute the automorphism and fundamental groups of von Neumann algebras of
a wide class of wreath-like products. As an application\, we show every fi
nitely presented group can be realised as the outer automorprhism group of
$\\text{L}(G)$ for a property (T) group $G$. This is based on joint work
with Ionut Chifan\, Denis Osin and Bin Sun.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Y. Choi (U. Lancaster\, UK)
DTSTART:20220603T140000Z
DTEND:20220603T153000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/43
DESCRIPTION:Title: Extensions\, unitarizability\, and amenable operator algebras\nby
Y. Choi (U. Lancaster\, UK) as part of Functional analysis and operator al
gebras in Athens\n\n\nAbstract\nIn work with Farah and Ozawa\, we exhibite
d a closed subalgebra of\n$\\ell^\\infty\\otimes {\\mathbb M}_2$ which is
amenable\, yet is not\nBanach-algebra-isomorphic to any $C^\\ast$-algebra\
; the non-isomorphism\nis witnessed by the failure to be "unitarizable" of
certain bounded\nsubgroups of matrix corona algebras. It remains an open
question\nwhether similar "counterexamples" can be found inside $C(K)\\oti
mes\n{\\mathbb M}_d$ for metrizable $K$. In this talk we report on some wo
rk\nin progress\, joint with B. Green (Lancaster)\, investigating what can
\nbe said when $K$ has finite Cantor-Bendixson rank.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20230113T130000Z
DTEND:20230113T150000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/44
DESCRIPTION:Title: Morita equivalence for operator systems I\nby E. Kakariadis (Newca
stle\, UK) as part of Functional analysis and operator algebras in Athens\
n\n\nAbstract\nIn ring theory\, Morita equivalence preserves many properti
es of the objects\, and generalizes the isomorphism equivalence between co
mmutative rings. A strong Morita equivalence for selfadjoint operator alge
bras was introduced by Rieffel in the 60s\, and works as a correspondence
between their representations. In the past 30 years there has been an inte
rest to develop a similar theory for nonselfadjoint operator algebras and
operator spaces with much success and in this talk we will review the main
points of these works. Then\, taking motivation from recent work of Conne
s and van Suijlekom\, we will present a Morita theory for operator systems
. We will give equivalent characterizations of Morita equivalence via Mori
ta contexts\, bihomomoprhisms and stable isomorphism\, while we will highl
ight properties that are preserved in this context. Finally we will provid
e applications to rigid systems\, function systems and non-commutative gra
phs. \n\nThis is joint work with George Eleftherakis and Ivan Todorov.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20230203T150000Z
DTEND:20230203T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/45
DESCRIPTION:Title: Morita equivalence for operator systems II\nby E. Kakariadis (Newc
astle\, UK) as part of Functional analysis and operator algebras in Athens
\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Lupini (Bologna\, It)
DTSTART:20230210T150000Z
DTEND:20230210T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/46
DESCRIPTION:Title: Definable refinements of classical algebraic invariants\nby M. Lup
ini (Bologna\, It) as part of Functional analysis and operator algebras in
Athens\n\n\nAbstract\nIn this talk I will explain how methods from logic
allow one to construct refinements of classical algebraic invariants that
are endowed with additional topological and descriptive set-theoretic info
rmation. This approach brings to fruition initial insights due to Eilenber
g\, Mac Lane\, and Moore (among others) with the additional ingredient of
recent advanced tools from logic. I will then present applications of this
viewpoint to invariants from a number of areas in mathematics\, including
operator algebras\, algebraic topology\, and homological algebra.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Raum (Stockholm\, Sw)
DTSTART:20230217T150000Z
DTEND:20230217T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/47
DESCRIPTION:Title: Detecting ideals in reduced crossed product C*-algebras of topological
dynamical systems\nby S. Raum (Stockholm\, Sw) as part of Functional
analysis and operator algebras in Athens\n\n\nAbstract\nCrossed products a
rising from topological dynamical systems are an important source of examp
les of C*-algebras and form ground for interaction between dynamics and op
erator algebras. Included in this class are reduced group C*-algebras whi
ch code representation theoretic information of a group. Sophisticated too
ls to prove (non-)simplicity of such C*-algebras have been developed over
the time. However\, they only apply to well-behaved dynamical systems or e
xclude a certain kind of amenable behaviour of the dynamical system. I wil
l make these statements precise and report on joint work with Are Austad (
University of Southern Denmark) in which we introduce the ℓ¹-ideal inte
rsection property. All non-zero ideals in the crossed product C*-algebra
of a dynamical system satisfying this property can be detected already ins
ide the much smaller and more concrete ℓ¹-crossed product. We prove th
at large classes of groups\, such as lattices in Lie groups and linear gro
ups over algebraic integers in a number field have this property for ANY a
ction on a locally compact Hausdorff space. The proof combines the theory
of twisted groupoid C*-algebras and C*-simplicity with structure results a
bout amenable subgroups.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Hoefer (Delaware\, USA)
DTSTART:20230224T150000Z
DTEND:20230224T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/48
DESCRIPTION:Title: Quantum hypergraph homomorphisms and applications to non-local games\nby G. Hoefer (Delaware\, USA) as part of Functional analysis and opera
tor algebras in Athens\n\n\nAbstract\nUtilizing the simulation paradigm in
information theory\, \nwe introduce notions of quantum hypergraph homomor
phisms and \nquantum hypergraph isomorphisms\nby considering different no-
signalling correlation classes and the hypergraphs the associated informat
ion \nchannels induce. We provide examples of separation between \nclassic
al and quantum hypergraph isomorphism. \n \nFor a given hypergraph isomor
phism game\, we show that the existence of perfect no-signalling (resp. qu
antum commuting\, quantum approximate) strategies can be \ncharacterized i
n terms of states on tensor products of canonical operator systems. \nWe f
urther focus on a sub-class of hypergraph homomorphism games where the hyp
ergraphs are themselves non-local games. We define strongly no-signalling
correlations and their various subtypes\, and investigate game strategy tr
ansport and the existence of perfect strategies for games using an operato
r system approach.\n\nThe talk will be based on a joint work with Ivan G.
Todorov.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:V. Paulsen (Waterloo\, Ca)
DTSTART:20230310T150000Z
DTEND:20230310T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/49
DESCRIPTION:Title: Matrix range characterizations of operator system properties\nby V
. Paulsen (Waterloo\, Ca) as part of Functional analysis and operator alge
bras in Athens\n\n\nAbstract\nGiven an operator system S\, one can create
two sequences of new operator systems from it\, denoted $OMAX_k(S)$ and $O
MIN_k(S)$. The first is the universal operator system with the property th
at every k-positive map with domain S is completely positive as a map from
$OMAX_k(S)$. The second has the property that every k-positive map with r
ange S is completely positive as a map into $OMIN_k(S)$. A natural questio
n is if these new operator systems in some sense ``converge to S" as k
tends to infinity. The answer is ``not always"\, but convergence does c
haracterize certain important properties of S. Finally\, when S is the fi
nite dimensional operator system spanned by an N-tuple of operators T=(T_1
\,...\,T_n)\, then these convergences can be characterized in terms of geo
metrical properties of the joint matricial ranges of T. Of special importa
nce is the case when (T_1\,...\,T_n) are the unitary generators of the uni
versal C*-algebra of the free group on n-generators.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. Beltita (Inst. Math. Romanian Acad.)
DTSTART:20230317T150000Z
DTEND:20230317T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/50
DESCRIPTION:Title: $C^*$-rigidity for certain exponential Lie groups\nby I. Beltita (
Inst. Math. Romanian Acad.) as part of Functional analysis and operator al
gebras in Athens\n\n\nAbstract\nA exponential Lie group is called (stably)
$C^*$-rigid if it is uniquely determined\, within the class of exponentia
l Lie groups\, by the class of isomorphism (Morita equivalence) of its $C^
*$ algebra. We discuss the problem of $C^*$-rigidity of exponential Lie gr
oups. In particular\, we show that generalized $ax+b$-groups are non-rigid
\, while nilpotent Lie groups of dimension less than equal to 5 are stably
$C^*$-rigid.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Daws (University of Central Lancashire\, UK)
DTSTART:20230303T150000Z
DTEND:20230303T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/51
DESCRIPTION:Title: Around the Approximation Property for Quantum Groups\nby Matthew D
aws (University of Central Lancashire\, UK) as part of Functional analysis
and operator algebras in Athens\n\n\nAbstract\nI will introduce what the
"approximation property" (AP) is for (locally compact) groups\, and provid
e a few applications. I will then talk about how one might give an analog
ous definition for (locally compact) quantum groups\, explaining some of t
he needed technology along the way.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavlos Motakis (York University)
DTSTART:20230324T150000Z
DTEND:20230324T170000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/52
DESCRIPTION:Title: Separable spaces of continuous functions as Calkin algebras\nby Pa
vlos Motakis (York University) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nFor a Banach space $X$ denote $\\mathca
l{L}(X) = \\{T:X\\to X\\text{ linear and bounded}\\}$ and $\\mathcal{K}(X)
= \\{T\\in\\mathcal{L}(X): T\\text{ compact}\\}$. The Calkin algebra of $
X$ is the Banach algebra $\\mathcal{C}al(X) = \\mathcal{L}(X)/\\mathcal{K}
(X)$. A question that has gathered attention in recent years is what unita
l Banach algebras admit representations as Calkin algebras. We discuss de
velopments in this topic as well as a recent contribution\, namely that fo
r every compact metric space $K$ there exists a Banach space $X$ so that $
\\mathcal{C}al(X)$ coincides isometrically with $C(K)$ as a Banach algebra
.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandros Eskenazis (Sorbonne\, Fr & Cambridge\, UK)
DTSTART:20230407T140000Z
DTEND:20230407T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/53
DESCRIPTION:Title: Discrete logarithmic Sobolev inequalities in Banach spaces\nby Ale
xandros Eskenazis (Sorbonne\, Fr & Cambridge\, UK) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nWe shall discuss ce
rtain aspects of vector-valued harmonic analysis on the discrete hypercube
. After presenting the geometric motivation behind such investigations\, w
e will survey known results on the Poincaré inequality and Talagrand’s
influence inequality. Then we will proceed to present a new optimal vector
-valued logarithmic Sobolev inequality in this context. The talk is based
on joint work with D. Cordero-Erausquin (Sorbonne).\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petros Valettas (U. Missouri\, USA)
DTSTART:20230519T140000Z
DTEND:20230519T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/56
DESCRIPTION:Title: Probabilistic Padé Problems\nby Petros Valettas (U. Missouri\, US
A) as part of Functional analysis and operator algebras in Athens\n\n\nAbs
tract\nIt has been observed\, by Froissart (1969)\, that zeros and poles o
f higher order Padé approximants of random perturbations of a determinist
ic Taylor series tend to form unstable pairs. These pairs appear at loci c
haracteristic of the random part in the coefficients of the Taylor series.
While this phenomenon has only been confirmed experimentally\, it has bee
n suggested\, and indeed used\, as a noise detection tool. In this talk we
will explain how techniques from high-dimensional probability and logarit
hmic potential theory can be melted together to rigorously establish and q
uantify the clustering of zeros in the ``pure noise’’ case\, when the
coefficients are drawn according to a distribution with anti-concentration
properties. \n\nBased on a joint ongoing work with S. Dostoglou (Universi
ty of Missouri).\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle U.\, UK)
DTSTART:20230331T120000Z
DTEND:20230331T140000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/57
DESCRIPTION:Title: Entropy and phase transitions for KMS-states of Pimsner-type algebras<
/a>\nby E.T.A. Kakariadis (Newcastle U.\, UK) as part of Functional analys
is and operator algebras in Athens\n\n\nAbstract\nThere is a well-develope
d theory of Kubo-Martin-Schwinger states (or equilibrium states) for C*-al
gebras\, which are motivated by the properties of Gibbs states for finite
matrices. They have attracted interest as they provide an invariant for cl
assification up to equivariant isomorphisms of C*-algebras. There has been
a growing study of their parametrization in particular for C*-algebras co
ming from Hilbert modules\, which are generalizations of the Toeplitz and
Cuntz algebras. In this talk I will give an overview about the theory of K
MS states in this setting and present how the notion of entropy allows to
identify phase transitions. Time permitting we will discuss how this works
for graph algebras and Nica-Pimsner algebras.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sarah Reznikoff (Kansas State U.\, USA)
DTSTART:20230428T140000Z
DTEND:20230428T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/58
DESCRIPTION:Title: Notes on regular ideals of C*-algebras\nby Sarah Reznikoff (Kansas
State U.\, USA) as part of Functional analysis and operator algebras in A
thens\n\n\nAbstract\nWe define and discuss the regular ideals of $C^*$-alg
ebras including the special case of graph algebras\, in particular propert
ies preserved by quotients of regular ideals. This is joint work with Jon
athan Brown\, Adam Fuller\, and David Pitts.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/58/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ebrahim Samei (U. Saskatchewan\, Canada)
DTSTART:20230505T140000Z
DTEND:20230505T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/59
DESCRIPTION:Title: New tensor products of C*-algebras and characterization of type I C*-a
lgebras as rigidly symmetric C*-algebras\nby Ebrahim Samei (U. Saskatc
hewan\, Canada) as part of Functional analysis and operator algebras in At
hens\n\n\nAbstract\nC*-algebras are studied through various tools and tech
niques including their tensor products. There are several classes of tens
or products that have been considered and studied extensively on C*-algebr
as. We introduce a new class of such objects using the theory of complex i
nterpolations on operator spaces. Our construction allows us to produce a
continuum family of distinct tensor product of the reduced C*-algebras of
nonamenable groups possessing both the rapid decay and Haagerup property.
We will show that they are in fact in the form of a Brown-Guentner type C*
-completion. As another application of our approach\, we provide a complet
e answer to a question of Leptin and Poguntke from 1979 proving that a C*-
algebra is rigidly symmetric if and only if it is type I. \n\nThis talk is
based on a joint work with Hun Hee Lee (SNU) and Matthew Wiersma (U of Wi
nnipeg).\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Petrakos (WWU Münster\, Germany)
DTSTART:20230512T140000Z
DTEND:20230512T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/60
DESCRIPTION:Title: Dynamical Alternating Groups\nby S. Petrakos (WWU Münster\, Germa
ny) as part of Functional analysis and operator algebras in Athens\n\n\nAb
stract\nTopological full groups form a very important class of groups aris
ing from\ndynamical systems and\, more generally\, étale groupoids. Their
subgroups\, especially the\nalternating subgroup\, have been proven to ex
hibit various properties\, some of which were\nrarely or never before witn
essed. In this talk I will introduce these groups in the dynamical\nsettin
g and go through some of the most important past results on the topic\, fo
cusing on\nthose of operator-algebraic interest. I will then briefly intro
duce the concept of almost\nfiniteness and present a recent result obtaine
d in joint work with Petr Naryshkin. We prove\nthat if a subgroup of a TFG
is amenable and contains the alternating subgroup\, then all its\nfree ac
tions on finite-dimensional compact metrizable spaces are almost finite.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Kopsacheilis (WWU Münster. Germany)
DTSTART:20230526T140000Z
DTEND:20230526T160000Z
DTSTAMP:20260422T225824Z
UID:AthensFAOA/61
DESCRIPTION:Title: A comparison type property for Cartan subalgebras\nby G. Kopsachei
lis (WWU Münster. Germany) as part of Functional analysis and operator al
gebras in Athens\n\n\nAbstract\nRegularity properties of C*-algebras are v
ital for classification theory. In the C*-setting\, finite nuclear dimensi
on\, tensorial absorption of the Jiang--Su algebra and strict comparison s
et the stage for Elliott's classification programme\; these properties are
known to be tightly related\, as the (to a large extent confirmed) Toms--
Winter conjecture predicts. On the dynamical side\, analogues of these hav
e been introduced for group actions\, and it is not yet quite clear how th
ese relate to the regularity properties of the crossed product. In this ta
lk\, we introduce a comparison type property in the context of Cartan suba
lgebras and study its relations to regularity properties of the ambient C*
-algebra\, and of the underlying dynamics\, when the inclusion arises from
a topological dynamical system. \nThis talk is based on joint work (in pr
ogress) with Wilhelm Winter.\n
LOCATION:https://researchseminars.org/talk/AthensFAOA/61/
END:VEVENT
END:VCALENDAR