BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201106T130000Z
DTEND:20201106T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/1
DESCRIPTION:Title: Operator algebraic introduction to non-local games\nby I. G.
Todorov (QUB & U. Delaware) as part of Functional analysis and operator a
lgebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201113T130000Z
DTEND:20201113T143000Z
DTSTAMP:20260404T111107Z
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
operator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201120T130000Z
DTEND:20201120T143000Z
DTSTAMP:20260404T111107Z
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
operator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. G. Todorov (QUB & U. Delaware)
DTSTART:20201127T130000Z
DTEND:20201127T143000Z
DTSTAMP:20260404T111107Z
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
operator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Giannopoulos (NKUA)
DTSTART:20201204T130000Z
DTEND:20201204T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/5
DESCRIPTION:Title: Isoperimetric constants of metric probability spaces\nby A.
Giannopoulos (NKUA) as part of Functional analysis and operator algebras i
n Athens\n\n\nAbstract\nIn this first talk we shall introduce four isoperi
metric\nconstants (the Cheeger constant\, the Poincare constant\, the expo
nential concentration\nconstant and the first moment concentration constan
t) associated with a Borel\nprobability measure on R^n and discuss their r
elation. We shall review classical\nresults of Maz'ya\, Cheeger\, Gromov\,
V. Milman\, Buser\, Ledoux and others\, as well as\na theorem of E. Milma
n which establishes the equivalence of all four constants in the\nlog-conc
ave setting.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Giannopoulos (NKUA)
DTSTART:20201211T130000Z
DTEND:20201211T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/6
DESCRIPTION:Title: Isoperimetric constants of metric probability spaces (2nd talk)<
/a>\nby A. Giannopoulos (NKUA) as part of Functional analysis and operator
algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kenneth R. Davidson (University of Waterloo)
DTSTART:20201218T140000Z
DTEND:20201218T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/7
DESCRIPTION:Title: Noncommutative Choquet theory (NOTE TIME)\nby Kenneth R. Dav
idson (University of Waterloo) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nWe introduce a new framework for noncom
mutative convexity. We develop a\nnoncommutative Choquet theory and prove
an analogue of the Choquet-Bishop-de Leeuw theorem.\nThis is joint work wi
th Matthew Kennedy.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Katavolos (NKUA)
DTSTART:20210108T140000Z
DTEND:20210108T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/8
DESCRIPTION:Title: Harmonic Operators and Crossed Products\nby A. Katavolos (NK
UA) as part of Functional analysis and operator algebras in Athens\n\n\nAb
stract\nWe study the space of harmonic operators for a probability measur
e μ (or a family of measures) on a group G\, as a “quantization” of
μ-harmonic (or jointly harmonic) functions on G. This leads to two differ
ent notions of crossed products of operator spaces by actions of G which c
oincide when G satisfies a certain approximation property. The correspondi
ng (dual) 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. Anouss
is and I.G. Todorov\, and of recent work by D. Andreou.\n \n\nFor Zoom me
eting coordinates and additional information see the seminar webpage\n\nht
tp://users.uoa.gr/~akatavol/anak2021.html#1\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:P. Dodos (NKUA)
DTSTART:20210115T140000Z
DTEND:20210115T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/9
DESCRIPTION:Title: High-dimensional random arrays. Structural decompositions and co
ncentration.\nby P. Dodos (NKUA) as part of Functional analysis and op
erator algebras in Athens\n\n\nAbstract\nA d-dimensional random array is a
stochastic process indexed by theset of all d-element subsets of a set I.
We shall discuss the structure of finite\,high-dimensional random arrays\
, with finite valued entries (e.g.\, boolean) whose distribution is
sufficiently symmetric. \nSpecifically\, we shall focus on the following i
nterrelated problems: concentration and distributional decompositions.
\nThis is joint work with Kostas Tyros and Petros Valettas\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:P. Dodos (NKUA)
DTSTART:20210122T140000Z
DTEND:20210122T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/10
DESCRIPTION:Title: High-dimensional random arrays. Structural decompositions and c
oncentration. (2nd talk)\nby P. Dodos (NKUA) as part of Functional ana
lysis and operator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210129T130000Z
DTEND:20210129T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/11
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210205T130000Z
DTEND:20210205T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/12
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No seminar
DTSTART:20210212T140000Z
DTEND:20210212T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/13
DESCRIPTION:by No seminar as part of Functional analysis and operator alge
bras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Siskakis (A.U. Thessaloniki)
DTSTART:20210219T140000Z
DTEND:20210219T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/14
DESCRIPTION:Title: The Hilbert matrix and its continuous version\nby A. Siskak
is (A.U. Thessaloniki) as part of Functional analysis and operator algebra
s in Athens\n\n\nAbstract\nWe will recount some known results on the discr
ete Hilbert matrix as an operator onspaces of analytic functions\, and wil
l consider the continuous version of the operator on suitablefunction spac
es. For the latter\, a theorem from Abstract Harmonic Analysis will be use
d todetermine its norm and spectrum.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Ghandehari (U. Delaware)
DTSTART:20210226T140000Z
DTEND:20210226T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/15
DESCRIPTION:Title: Fourier algebras of the group of R-affine transformations and a
dual convolution.\nby M. Ghandehari (U. Delaware) as part of Function
al analysis and operator algebras in Athens\n\n\nAbstract\nA major trend i
n Non-commutative Harmonic Analysis is to investigate function spaces rela
ted toFourier analysis (and representation theory) of non-abelian groups.
The Fourier algebra\, which is associatedwith the left regular represent
ation of the ambient group\, is an important example of such function spac
es. Thisfunction algebra encodes the properties of the group in various w
ays\; for instance the existence of derivationson this algebra translates
into information about the commutativity of the group itself.In this talk\
, we investigate the Fourier algebra of the group ofR-affine transformatio
ns. In particular\, wediscuss the non-commutative Fourier transform for t
his group\, and provide an explicit formula for the convolutionproduct on
the “dual side” of this transform. As an application of this new dual
convolution product\, we showan easy dual formulation for (the only known
) symmetric derivative on the Fourier algebra of the group.This talk is ma
inly based on joint articles with Y. Choi.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. G. Katsoulis (ECU\, USA)
DTSTART:20210305T140000Z
DTEND:20210305T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/16
DESCRIPTION:Title: Co-universal C*-algebras for product systems\nby E. G. Kats
oulis (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 p
aper of A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with X. Li. The
emphasis is on the interaction between selfadjoint and nonselfadjoint ope
rator algebra theory with applications to current problems in C*-algebra t
heory. Significant effort will be made in carefully reviewing preliminarie
s\, including basic facts from the theory of C*-envelopes and product syst
ems.\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. Discret
e product systems are semigroup versions of C*-correspondences\, that allo
w for a joint study of many fundamental C*-algebras\, including those whic
h come from C*-correspondences\, higher rank graphs and elsewhere.\n\nKats
ura’s covariant relations have been proven to give the correct Cuntz-typ
e C*-algebra for a C*-correspondence X. One of the great advantages Katsur
a’s Cuntz-Pimsner C*-algebra is its co-universality for the class of gau
ge-compatible injective representations of X. In the late 2000s Carlsen-La
rsen-Sims-Vittadello raised the question of the existence of such a co-uni
versal object in the context of product systems. In their work\, Carlsen-L
arsen-Sims-Vittadello provided an affirmative answer for quasi-lattices\,
with additional injectivity assumptions on X. The general case has remaine
d open and will be addressed in these talks using tools from non-selfadjoi
nt operator algebra theory.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. G. Katsoulis (ECU\, USA)
DTSTART:20210312T140000Z
DTEND:20210312T153000Z
DTSTAMP:20260404T111107Z
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 a
lgebras in Athens\n\n\nAbstract\nIn these talks we will present parts of t
he recent paper of A. Dor-On\, E. Kakariadis\, E. Katsoulis\, M. Laca with
X. Li. The emphasis is on the interaction between selfadjoint and nonself
adjoint operator algebra theory with applications to current problems in C
*-algebra theory. Significant effort will be made in carefully reviewing p
reliminaries\, including basic facts from the theory of C*-envelopes and p
roduct systems.\n\nContinuous product systems were introduced and studied
by Arveson in the late 1980s. The study of their discrete analogues starte
d with the work of Dinh in the 1990s and it was formalized by Fowler in 20
02. Discrete 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 elsewhe
re.\n\nKatsura’s covariant relations have been proven to give the correc
t Cuntz-type C*-algebra for a C*-correspondence X. One of the great advant
ages Katsura’s Cuntz-Pimsner C*-algebra is its co-universality for the c
lass of gauge-compatible injective representations of X. In the late 2000s
Carlsen-Larsen-Sims-Vittadello raised the question of the existence of su
ch a co-universal object in the context of product systems. In their work\
, Carlsen-Larsen-Sims-Vittadello provided an affirmative answer for quasi-
lattices\, with additional injectivity assumptions on X. The general case
has remained open and will be addressed in these talks using tools from no
n-selfadjoint operator algebra theory.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20210319T140000Z
DTEND:20210319T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/18
DESCRIPTION:Title: Co-universal C*-algebras for product systems\, 3rd talk\nby
E. Kakariadis (Newcastle\, UK) as part of Functional analysis and operat
or 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 emphasis is on the interaction between selfadjoint and non
selfadjoint operator algebra theory with applications to current problems
in C*-algebra theory. Significant effort will be made in carefully reviewi
ng preliminaries\, including basic facts from the theory of C*-envelopes a
nd product systems.\n\nContinuous product systems were introduced and stud
ied by Arveson in the late 1980s. The study of their discrete analogues st
arted with the work of Dinh in the 1990s and it was formalized by Fowler i
n 2002. Discrete product systems are semigroup versions of C*-corresponden
ces\, that allow for a joint study of many fundamental C*-algebras\, inclu
ding those which come from C*-correspondences\, higher rank graphs and els
ewhere.\n\nKatsura’s covariant relations have been proven to give the co
rrect Cuntz-type C*-algebra for a C*-correspondence X. One of the great ad
vantages Katsura’s Cuntz-Pimsner C*-algebra is its co-universality for t
he class of gauge-compatible injective representations of X. In the late 2
000s Carlsen-Larsen-Sims-Vittadello raised the question of the existence o
f such a co-universal object in the context of product systems. In their w
ork\, Carlsen-Larsen-Sims-Vittadello provided an affirmative answer for qu
asi-lattices\, with additional injectivity assumptions on X. The general c
ase has remained open and will be addressed in these talks using tools fro
m non-selfadjoint operator algebra theory.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20210326T140000Z
DTEND:20210326T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/19
DESCRIPTION:Title: Co-universal C*-algebras for product systems\, 4th talk\nby
E. Kakariadis (Newcastle\, UK) as part of Functional analysis and operat
or 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 emphasis is on the interaction between selfadjoint and non
selfadjoint operator algebra theory with applications to current problems
in C*-algebra theory. Significant effort will be made in carefully reviewi
ng preliminaries\, including basic facts from the theory of C*-envelopes a
nd product systems.\n\nContinuous product systems were introduced and stud
ied by Arveson in the late 1980s. The study of their discrete analogues st
arted with the work of Dinh in the 1990s and it was formalized by Fowler i
n 2002. Discrete product systems are semigroup versions of C*-corresponden
ces\, that allow for a joint study of many fundamental C*-algebras\, inclu
ding those which come from C*-correspondences\, higher rank graphs and els
ewhere.\n\nKatsura’s covariant relations have been proven to give the co
rrect Cuntz-type C*-algebra for a C*-correspondence X. One of the great ad
vantages Katsura’s Cuntz-Pimsner C*-algebra is its co-universality for t
he class of gauge-compatible injective representations of X. In the late 2
000s Carlsen-Larsen-Sims-Vittadello raised the question of the existence o
f such a co-universal object in the context of product systems. In their w
ork\, Carlsen-Larsen-Sims-Vittadello provided an affirmative answer for qu
asi-lattices\, with additional injectivity assumptions on X. The general c
ase has remained open and will be addressed in these talks using tools fro
m non-selfadjoint operator algebra theory.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo Laca (University of Victoria\, Canada)
DTSTART:20210402T130000Z
DTEND:20210402T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/20
DESCRIPTION:Title: C*-algebras generated by isometries: 60 years and counting\
nby Marcelo Laca (University of Victoria\, Canada) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nThe first talk will
be a (necessarily biased and partial) survey of the history of\nC*-algebr
as generated by isometries on Hilbert space. I will begin by recalling\ncl
assical theorems of Coburn\, Douglas\, and Cuntz from the 1960’s and 197
0’s\nand 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 1990’s when Murphy\,\nStacey\, Nica\, and then Raeburn and I devel
oped an explicit semigroup crossed\nproduct approach for Toeplitz algebras
\, focusing on a covariance condition that\nworks quite well for quasi-lat
tice ordered groups. I will elaborate a bit on this\napproach and show how
it works in a few examples. I will finish by discussing\nbriefly the semi
group C*-algebra C^*_s(P) introduced by Xin Li in the 2010’s \nusing con
structible right ideals to generalize Nica’s covariance condition\, and
will\nfinish by giving some non quasi-lattice ordered examples from number
theory.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo Laca (University of Victoria\, Canada)
DTSTART:20210409T130000Z
DTEND:20210409T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/21
DESCRIPTION:Title: C*-algebras generated by isometries: 60 years and counting\
nby Marcelo Laca (University of Victoria\, Canada) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nThe second talk wil
l be on my joint work with Sehnem from the 2020’s about\na universal Toe
plitz algebra T_u(P) defined via generators and relations whenever\nP is a
submonoid of a group G. The C*-algebra T_u(P) coincides with Xin Li’s\n
C_s^∗(P) when the semigroup satisfies his independence condition but beh
aves\nas expected also when independence fails\; for example\, it is isomo
rphic to the\nC*-algebra of the left regular representation when the group
G is amenable and\nalso in many nonamenable situations. I will give a cha
racterization of faithful\nrepresentations and a uniqueness theorem for th
ese universal Toeplitz algebras\,\nwhich are new results even for right LC
M monoids. 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)\,
generalizing the boundary relations of quasi-lattice\norders introduced b
y Crisp and myself in the 2000’s.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Kennedy (University of Waterloo\, Canada)
DTSTART:20210416T130000Z
DTEND:20210416T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/22
DESCRIPTION:Title: Amenability\, proximality and higher order syndeticity\nby
Matthew Kennedy (University of Waterloo\, Canada) as part of Functional an
alysis and operator algebras in Athens\n\n\nAbstract\nI will present new d
escriptions of some universal flows associated to a discrete group\, obtai
ned using what we view as a kind of “topological Furstenberg corresponde
nce.” The descriptions are algebraic and relatively concrete\, involvin
g subsets of the group satisfying a higher order notion of syndeticity. We
utilize them to establish new necessary and sufficient conditions for str
ong amenability and amenability. Furthermore\, utilizing similar technique
s\, we obtain a characterization of “dense orbit sets\,” answering a q
uestion of Glasner\, Tsankov\, Weiss and Zucker. Throughout the talk\, I w
ill discuss connections to operator algebras. \nThis is joint work with Sv
en Raum and Guy Salomon.\n\nFor Zoom meeting coordinates\nand additional i
nformation see the seminar webpage\n\nhttp://users.uoa.gr/~akatavol/anak20
21.html#1\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xin Li (University of Glasgow\, UK)
DTSTART:20210423T130000Z
DTEND:20210423T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/23
DESCRIPTION:Title: Semigroup C*-algebras and their K-theory\nby Xin Li (Univer
sity of Glasgow\, UK) as part of Functional analysis and operator algebras
in Athens\n\n\nAbstract\nI will report on developments in semigroup C*-al
gebras\, with a particular focus on examples\, structural properties and c
lassification results. A key ingredient is given by a K-theory formula\, w
hich has been generalized recently\, as we will discuss.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Daws (University of Central Lancashire\, UK)
DTSTART:20210514T130000Z
DTEND:20210514T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/24
DESCRIPTION:Title: Purely infinite algebras and ultrapowers\nby Matthew Daws (
University of Central Lancashire\, UK) as part of Functional analysis and
operator algebras in Athens\n\n\nAbstract\nI will discuss what it means fo
r a Banach Algebra to be purely infinite (with a brief nod towards the imp
ortant class of purely infinite C*-algebras). The ultrapower construction
is an interesting\nway to convert "approximate" relations into exact ones\
, and has\nimportant links to (continuous) model theory. We ask the questi
on:\nwhen does a purely infinite Banach algebra have purely infinite\nultr
apowers? This is equivalent to having a "quantified" version of\nbeing pur
ely infinite\, where one has norm control over certain\nchoices. This is a
lways so for C*-algebras\, but we present some\nexamples of Banach algebra
s where this works\, and where it doesn't.\nOur examples are rather "natur
al"\, in the sense that we don't just\nfiddle with the norm of elements. T
his is joint work with Bence\nHorvath.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sophie Grivaux (Université de Lille\, FR)
DTSTART:20210521T130000Z
DTEND:20210521T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/25
DESCRIPTION:Title: Typical properties of contractions on l_p spaces\nby Sophie
Grivaux (Université de Lille\, FR) as part of Functional analysis and op
erator algebras in Athens\n\n\nAbstract\nGiven a separable Banach space $X
$ of infinite dimension\, one can consider on the space $\\mathcal{B}(X)$
of bounded linear operators on $X$ several \nnatural topologies which turn
the closed unit ball $B_1(X)=\\{T\\in\\mathcal{B}(X)\;||T||\\le 1\\}$ int
o a Polish space\, i.e. a separable and completely metrizable space. \n\nI
n this talk\, I will present some results concerning typical properties in
the Baire Category sense of operators of $B_1(X)$ for these \ntopologies
when $X$ is a $\\ell_p$-space\, our main interest being to determine wheth
er typical contractions on these spaces have a non-trivial invariant subsp
ace or not. \n\nThe talk is based on joint work with \\'Etienne Matheron a
nd Quentin Menet.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Sherman (University of Virginia\, USA)
DTSTART:20210528T130000Z
DTEND:20210528T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/26
DESCRIPTION:Title: A quantization of coarse structures and uniform Roe algebras\nby David Sherman (University of Virginia\, USA) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nA coarse structure
is a way of talking about "large-scale" properties. It is encoded in a f
amily of relations that often\, but not always\, come from a metric. A coa
rse structure naturally gives rise to Hilbert space operators that in turn
generate a so-called uniform Roe algebra.\nIn ongoing work with Bruno Bra
ga and Joe Eisner\, we use ideas of Weaver to construct "quantum" coarse s
tructures and uniform Roe algebras in which the underlying set is replaced
with an arbitrary represented von Neumann algebra. The general theory i
mmediately 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*-algebra
s.\nI will present the big picture: where uniform Roe algebras come from\,
how Weaver's framework facilitates our definitions. I will focus on a few
illustrative examples and will not assume any familiarity with coarse str
uctures or von Neumann algebras.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle\, UK)
DTSTART:20220211T150000Z
DTEND:20220211T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/27
DESCRIPTION:Title: Rigidity of analytic operator algebras\nby E.T.A. Kakariadi
s (Newcastle\, UK) as part of Functional analysis and operator algebras in
Athens\n\n\nAbstract\nAbstract: In the past 20 years\, nonselfadjoint alg
ebras have been proven to\nprovide complete invariants for geometric struc
tures. This follows from a\ncombination of techniques from Complex Analysi
s\, Functional Analysis and\nAlgebra. In this talk I will survey on rigidi
ty results for analytic operator\nalgebras related to subproduct systems a
nd semigroups. In some cases\, this is in\nstark contrast to what happens
with C*-algebras.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle\, UK)
DTSTART:20220218T150000Z
DTEND:20220218T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/28
DESCRIPTION:Title: Rigidity of analytic operator algebras (2nd talk)\nby E.T.A
. Kakariadis (Newcastle\, UK) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nAbstract: In the past 20 years\, nonself
adjoint algebras have been proven to\nprovide complete invariants for geom
etric structures. This follows from a\ncombination of techniques from Comp
lex Analysis\, Functional Analysis and\nAlgebra. In this talk I will surve
y on rigidity results for analytic operator\nalgebras related to subproduc
t systems and semigroups. In some cases\, this is in\nstark contrast to wh
at happens with C*-algebras.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. Spronk (Waterloo\, Canada)
DTSTART:20220225T150000Z
DTEND:20220225T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/29
DESCRIPTION:Title: Topologies\, idempotents and ideals\nby N. Spronk (Waterloo
\, Canada) as part of Functional analysis and operator algebras in Athens\
n\n\nAbstract\nLet $G$ be a topological group. I wish to exhibit a bijecti
on between (i) a certain class of weakly almost periodic topologies\, (ii)
idempotents in the weakly almost periodic compactification of $G$\, and (
iii) certain ideals of the algebra of weakly almost periodic functions. Th
is has applications to decomposing weakly almost periodic representations
on Banach spaces\, generalizing results which go back to many authors.\n\n
Moving to unitary representations\, I will develop the Fourier-Stieltjes a
lgebra $B(G)$ of $G$\, and give the analogous result there. As an applicat
ion\, I show that for a locally compact connected group\, operator amenabi
lity of $B(G)$ implies that $G$ is compact\, partially resolving a problem
of interest for 25 years.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D. Andreou (NKUA)
DTSTART:20220304T150000Z
DTEND:20220304T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/30
DESCRIPTION:Title: Crossed products of operator spaces and approximation propertie
s\nby D. Andreou (NKUA) as part of Functional analysis and operator al
gebras in Athens\n\n\nAbstract\nWe will discuss two notions of crossed pro
duct for group actions as\nwell as coactions on dual operator spaces\, whi
ch generalize the usual von\nNeumann algebra crossed product. The goal is
to describe certain group\napproximation conditions\, such as the Haagerup
-Kraus approximation property\nand Ditkin's condition at infinity\, throug
h properties of the associated crossed\nproduct functors.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220422T140000Z
DTEND:20220422T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/31
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and oper
ator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220429T140000Z
DTEND:20220429T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/32
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and oper
ator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefaan Vaes (KU Leuven)
DTSTART:20220506T140000Z
DTEND:20220506T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/33
DESCRIPTION:Title: W$^*$-rigidity paradigms for embeddings of II$_1$ factors\n
by Stefaan Vaes (KU Leuven) as part of Functional analysis and operator al
gebras in Athens\n\n\nAbstract\nI will report on a joint work with Sorin P
opa in which we undertake a systematic study on the following question: wh
en can a given II$_1$ factor be embedded into another given II$_1$ factor?
More generally\, we say that a II$_1$ factor $M$ stably embeds into a II$
_1$ factor $N$ if $M$ may be realized as a subfactor of an amplification o
f $N$\, not necessarily of finite index. We provide families of II$_1$ fac
tors that are mutually non stably embeddable\, as well as families that ar
e mutually embeddable\, yet nonisomorphic. We prove that the preorder rela
tion of stable embeddability is as complicated as it can be since it conta
ins any partially ordered set. We also obtain numerous computations of inv
ariants of II$_1$ factors\, including descriptions of all stable self embe
ddings\, outer automorphism groups\, etc.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tr. Russell (U.S.M.A. Westpoint)
DTSTART:20220415T140000Z
DTEND:20220415T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/34
DESCRIPTION:Title: An operator system approach to quantum correlations\nby Tr.
Russell (U.S.M.A. Westpoint) as part of Functional analysis and operator
algebras in Athens\n\n\nAbstract\nIn this talk\, I will explain a novel ap
proach to Tsirelson's problem\nusing the theory of operator systems. Tsire
lson's problem relates to whether the\ncommuting operator model of quantum
mechanics produces different statistics\nthan the tensor product model of
quantum mechanics in non-local measurement\nscenarios. These questions ha
ve been shown to be equivalent to Connes'\nembedding problem from the theo
ry of Von Neumann algebras. After\ntremendous effort by physicists\, mathe
maticians\, and computer scientists\,\nTsirelson's problem was finally res
olved in a recent paper. Nevertheless\,\ninterest in understanding Tsirels
on's problem in greater detail remains. After\nexploring some background i
n the theory of operator systems\, I will explain\nhow to characterize qua
ntum correlations using only abstract operator system\ntheory\, building u
pon existing C*-algebraic and operator theoretic\ncharacterizations in the
literature. This new characterization yields an\nequivalent restatement o
f Tsirelson's problem in the language of abstract\noperator systems.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Pisier (Texas A&M\, USA\, Sorbonne Universite\, Fr.)
DTSTART:20220311T150000Z
DTEND:20220311T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/35
DESCRIPTION:Title: The lifting property for C* algebras\nby G. Pisier (Texas A
&M\, USA\, Sorbonne Universite\, Fr.) as part of Functional analysis and o
perator algebras in Athens\n\n\nAbstract\nWe give several characterization
s of the lifting property (LP in short) using the maximal tensor product f
or C* -algebras. The class of algebras with LP includes all nuclear C*-alg
ebras but also the full C*-algebras of free groups. The local version of t
he LP (LLP in short) will be discussed in connection with the problem whet
her the local LP implies the global LP in the separable case.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:O.M. Shalit (Technion\, Haifa)
DTSTART:20220513T140000Z
DTEND:20220513T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/36
DESCRIPTION:Title: CP-semigroups and dilations\, subproduct systems and superprodu
ct systems\nby O.M. Shalit (Technion\, Haifa) as part of Functional an
alysis and operator algebras in Athens\n\n\nAbstract\nIn a joint work with
Michael Skeide\, we introduce a framework for studying dilations of semig
roups of completely positive maps on C*-algebras. The heart of our method
is the systematic use of families of Hilbert C*-correspondences that behav
e nicely with respect to tensor products: these are product systems\, subp
roduct systems and superproduct systems. Although we developed our tools w
ith the goal of understanding the multi-parameter case\, they also lead to
new results even in the well studied one parameter case. In my talk I wil
l give a broad outline of our work.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D. Pitts (University of Nebraska-Lincoln)
DTSTART:20220408T140000Z
DTEND:20220408T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/37
DESCRIPTION:Title: Normalizers and Approximate Units for Inclusions of C*-Algebras
\nby D. Pitts (University of Nebraska-Lincoln) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nConsider {\\it incl
usions}\, which are pairs of $C^*$-algebras $(C\,D)$ with $D$ an abelian s
ubalgebra of $C$. An element $v\\in C$ {\\it normalizes} $D$ if $v^*D v
\\cup vDv^* \\subseteq D$. The inclusion $(C\,D)$ is {\\it regular} when
the linear span of the normalizers is dense in $C$ and is {\\it singular}
when every normalizer belongs to $D$.\n\nI will prove a commutation result
for Hermitian normalizers\, then discuss some consequences of this resul
t related to familiar constructions. Sample consequence:\nwhen $D$ is a r
egular 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 intermediate} to the regular MASA inclusion $(B\,D)$ if $D\\subseteq C
\\subseteq B$.\nI will give examples showing some singular MASA inclusions
are intermediate to regular MASA inclusions\, but others are not\, and wi
ll discuss the fact that when $\\mathcal H$ is a separable\, infinite dim
ensional Hilbert space\, no MASA inclusion of the form $(\\mathcal B(\\mat
hcal H)\, D)$ is intermediate to a regular MASA inclusion.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Gillaspy (U. Montana\, USA)
DTSTART:20220527T140000Z
DTEND:20220527T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/38
DESCRIPTION:Title: Cartan subalgebras in groupoid C*-algebras\nby E. Gillaspy
(U. Montana\, USA) as part of Functional analysis and operator algebras in
Athens\n\n\nAbstract\nBuilding on earlier work of Kumjian\, Renault prove
d in 2008 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
groupoid $W$ does not have to be topologically principal in order to const
ruct $C^*(W\; S)$. Do those more general groupoid C*-algebras have Cartan
subalgebras\, and if so\, what is the relationship between the Weyl groupo
id and the original groupoid?\n\n \n\nIn joint work with A. Duwenig\, R. N
orton\, S. Reznikoff\, and S. Wright\, we identified situations when a sub
groupoid $S$ of a non-principal groupoid $G$ will give rise to a Cartan su
balgebra $B = C^*(S)$ of $A = C^*(G)$. Subsequent work\, joint with A. Du
wenig and R. Norton\, revealed that in this case\, the Weyl groupoid $W$ o
f the pair $(B\, A)$ is a semidirect product: $W = G/S \\ltimes \\widehat{
S}$. We also describe the Weyl twist explicitly in the situation where th
ere 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 valid 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 talk will not assume familiarity with groupoids\, their C*-algebras\,
or Cartan subalgebras for C*-algebras\, and should (I hope) be more compre
hensible.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Brannan (U. Waterloo\, Canada)
DTSTART:20220520T130000Z
DTEND:20220520T143000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/39
DESCRIPTION:Title: Quantum path spaces\, correspondences\, and quantum Cuntz-Krieg
er algebras NOTE UNUSUAL TIME\nby M. Brannan (U. Waterloo\, Canada) as
part of Functional analysis and operator algebras in Athens\n\n\nAbstract
\nIn recent years there has been a significant interest in studying genera
lizations of graphs within the framework of noncommutative geometry. Such
objects are called quantum graphs. In this talk I will explain what a qu
antum graph is\, and also introduce quantum Cuntz-Krieger (QCK) algebras\,
which are a class of universal C*-algebras associated to quantum graphs p
reviously introduced by Eifler\, Voigt\, Weber and the speaker. \nAs th
e name suggests\, QCK algebras generalize Cuntz-Krieger algebras of ordina
ry graphs\, but they turn out to be very hard to understand. In this talk
I will explain some attempts to better understand QCK algebras by consider
ing quantum analogues of graph correspondences and their associated Cuntz-
Pimsner algebras\, as well as infinite quantum path spaces and their assoc
iated Exel crossed products. \nThis is based on joint work with Mitch Ham
idi\, Lara Ismert\, Brent Nelson and Mateusz Wasilewski.\n\nNOTE UNUSUAL T
IME\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Ghandehari (U. Delaware)
DTSTART:20220318T150000Z
DTEND:20220318T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/40
DESCRIPTION:Title: Meaningful decay behavior of higher dimensional continuous wave
let transforms\nby M. Ghandehari (U. Delaware) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nThe wavefront set o
f a tempered distribution $u$ is the set of points $t\\in{\\mathbb R}^n$ a
nd directions $\\xi$ in the sphere $S^{n-1}$ along which $u$ is not smooth
at $t$. In the recent years\, certain wavelet-type transformations (for e
xample the curvelet or shearlet transformation) have gained considerable a
ttention\, due to their potential for identifying the wavefront set of a s
ignal by inspecting the decay rate of the corresponding transformation coe
fficients. \n\nRecently\, many efforts have been made aiming to generalize
the above characterization for higher dimensional cases. Higher dimension
al wavelet transforms are constructed using square-integrable representati
ons of ${\\mathbb R}^n\\rtimes H$ where $H$ can be any suitably chosen dil
ation group. In this talk\, we consider the problem of characterizing the
Sobolev wavefront set of a distribution for a higher-dimensional wavelet t
ransform in two important cases where: 1) the mother wavelet is compactly
supported\, and 2) the mother wavelet has compactly supported Fourier tran
sform. \n\nThis talk is based on an ongoing joint project with Hartmut Fuh
r.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO TALK
DTSTART:20220325T150000Z
DTEND:20220325T163000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/41
DESCRIPTION:Title: NO TALK\nby NO TALK as part of Functional analysis and oper
ator algebras in Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Ioana (UCSD\, USA)
DTSTART:20220401T140000Z
DTEND:20220401T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/42
DESCRIPTION:Title: Wreath-like product groups and rigidity of their von Neumann al
gebras\nby A. Ioana (UCSD\, USA) as part of Functional analysis and op
erator algebras in Athens\n\n\nAbstract\nIn this talk\, I will introduce a
new class of groups\, called wreath-like products. These groups are close
relatives of the classical wreath products and arise naturally in the con
text of group theoretic Dehn filling. Unlike ordinary wreath products\, ma
ny wreath-like products have Kazhdan's property (T). I will present severa
l new rigidity results for von Neumann algebras of wreath-like products wi
th property (T). In particular\, we obtain the first examples of property
(T) groups $G$ which are W*-superrigid\, in the sense that the group von
Neumann algebra $\\text{L}(G)$ remembers the isomorphism class of $G$. We
also compute the automorphism and fundamental groups of von Neumann algeb
ras of a wide class of wreath-like products. As an application\, we show e
very finitely presented group can be realised as the outer automorprhism g
roup of $\\text{L}(G)$ for a property (T) group $G$. This is based on join
t work with Ionut Chifan\, Denis Osin and Bin Sun.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Y. Choi (U. Lancaster\, UK)
DTSTART:20220603T140000Z
DTEND:20220603T153000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/43
DESCRIPTION:Title: Extensions\, unitarizability\, and amenable operator algebras\nby Y. Choi (U. Lancaster\, UK) as part of Functional analysis and oper
ator algebras in Athens\n\n\nAbstract\nIn work with Farah and Ozawa\, we e
xhibited a closed subalgebra of\n$\\ell^\\infty\\otimes {\\mathbb M}_2$ wh
ich is amenable\, yet is not\nBanach-algebra-isomorphic to any $C^\\ast$-a
lgebra\; the non-isomorphism\nis witnessed by the failure to be "unitariza
ble" of certain bounded\nsubgroups of matrix corona algebras. It remains a
n open question\nwhether similar "counterexamples" can be found inside $C(
K)\\otimes\n{\\mathbb M}_d$ for metrizable $K$. In this talk we report on
some work\nin progress\, joint with B. Green (Lancaster)\, investigating w
hat can\nbe said when $K$ has finite Cantor-Bendixson rank.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20230113T130000Z
DTEND:20230113T150000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/44
DESCRIPTION:Title: Morita equivalence for operator systems I\nby E. Kakariadis
(Newcastle\, UK) as part of Functional analysis and operator algebras in
Athens\n\n\nAbstract\nIn ring theory\, Morita equivalence preserves many p
roperties of the objects\, and generalizes the isomorphism equivalence bet
ween commutative rings. A strong Morita equivalence for selfadjoint operat
or algebras was introduced by Rieffel in the 60s\, and works as a correspo
ndence between their representations. In the past 30 years there has been
an interest to develop a similar theory for nonselfadjoint operator algebr
as and operator spaces with much success and in this talk we will review t
he main points of these works. Then\, taking motivation from recent work o
f Connes and van Suijlekom\, we will present a Morita theory for operator
systems. We will give equivalent characterizations of Morita equivalence v
ia Morita contexts\, bihomomoprhisms and stable isomorphism\, while we wil
l highlight properties that are preserved in this context. Finally we will
provide applications to rigid systems\, function systems and non-commutat
ive graphs. \n\nThis is joint work with George Eleftherakis and Ivan Todor
ov.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. Kakariadis (Newcastle\, UK)
DTSTART:20230203T150000Z
DTEND:20230203T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/45
DESCRIPTION:Title: Morita equivalence for operator systems II\nby E. Kakariadi
s (Newcastle\, UK) as part of Functional analysis and operator algebras in
Athens\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. Lupini (Bologna\, It)
DTSTART:20230210T150000Z
DTEND:20230210T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/46
DESCRIPTION:Title: Definable refinements of classical algebraic invariants\nby
M. Lupini (Bologna\, It) as part of Functional analysis and operator alge
bras in Athens\n\n\nAbstract\nIn this talk I will explain how methods from
logic allow one to construct refinements of classical algebraic invariant
s that are endowed with additional topological and descriptive set-theoret
ic information. This approach brings to fruition initial insights due to E
ilenberg\, Mac Lane\, and Moore (among others) with the additional ingredi
ent of recent advanced tools from logic. I will then present applications
of this viewpoint to invariants from a number of areas in mathematics\, in
cluding operator algebras\, algebraic topology\, and homological algebra.\
n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Raum (Stockholm\, Sw)
DTSTART:20230217T150000Z
DTEND:20230217T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/47
DESCRIPTION:Title: Detecting ideals in reduced crossed product C*-algebras of topo
logical dynamical systems\nby S. Raum (Stockholm\, Sw) as part of Func
tional analysis and operator algebras in Athens\n\n\nAbstract\nCrossed pro
ducts arising from topological dynamical systems are an important source o
f examples of C*-algebras and form ground for interaction between dynamics
and operator algebras. Included in this class are reduced group C*-algeb
ras which code representation theoretic information of a group. Sophistica
ted tools to prove (non-)simplicity of such C*-algebras have been develope
d over the time. However\, they only apply to well-behaved dynamical syste
ms or exclude a certain kind of amenable behaviour of the dynamical system
. I will make these statements precise and report on joint work with Are A
ustad (University of Southern Denmark) in which we introduce the ℓ¹-ide
al intersection property. All non-zero ideals in the crossed product C*-a
lgebra of a dynamical system satisfying this property can be detected alre
ady inside the much smaller and more concrete ℓ¹-crossed product. We p
rove that large classes of groups\, such as lattices in Lie groups and lin
ear groups over algebraic integers in a number field have this property fo
r ANY action on a locally compact Hausdorff space. The proof combines the
theory of twisted groupoid C*-algebras and C*-simplicity with structure re
sults about amenable subgroups.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Hoefer (Delaware\, USA)
DTSTART:20230224T150000Z
DTEND:20230224T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/48
DESCRIPTION:Title: Quantum hypergraph homomorphisms and applications to non-local
games\nby G. Hoefer (Delaware\, USA) as part of Functional analysis an
d operator algebras in Athens\n\n\nAbstract\nUtilizing the simulation para
digm in information theory\, \nwe introduce notions of quantum hypergraph
homomorphisms and \nquantum hypergraph isomorphisms\nby considering differ
ent no-signalling correlation classes and the hypergraphs the associated i
nformation \nchannels induce. We provide examples of separation between \n
classical and quantum hypergraph isomorphism. \n \nFor a given hypergraph
isomorphism game\, we show that the existence of perfect no-signalling (r
esp. quantum commuting\, quantum approximate) strategies can be \ncharacte
rized in terms of states on tensor products of canonical operator systems.
\nWe further focus on a sub-class of hypergraph homomorphism games where
the hypergraphs are themselves non-local games. We define strongly no-sign
alling correlations and their various subtypes\, and investigate game stra
tegy transport and the existence of perfect strategies for games using an
operator system approach.\n\nThe talk will be based on a joint work with I
van G. Todorov.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:V. Paulsen (Waterloo\, Ca)
DTSTART:20230310T150000Z
DTEND:20230310T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/49
DESCRIPTION:Title: Matrix range characterizations of operator system properties\nby V. Paulsen (Waterloo\, Ca) as part of Functional analysis and operat
or algebras 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 $OMIN_k(S)$. The first is the universal operator system with the prop
erty that every k-positive map with domain S is completely positive as a m
ap from $OMAX_k(S)$. The second has the property that every k-positive map
with range S is completely positive as a map into $OMIN_k(S)$. A natural
question 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 characterize certain important properties of S. Finally\, when S is
the finite dimensional operator system spanned by an N-tuple of operators
T=(T_1\,...\,T_n)\, then these convergences can be characterized in terms
of geometrical properties of the joint matricial ranges of T. Of special
importance is the case when (T_1\,...\,T_n) are the unitary generators of
the universal C*-algebra of the free group on n-generators.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. Beltita (Inst. Math. Romanian Acad.)
DTSTART:20230317T150000Z
DTEND:20230317T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/50
DESCRIPTION:Title: $C^*$-rigidity for certain exponential Lie groups\nby I. Be
ltita (Inst. Math. Romanian Acad.) as part of Functional analysis and oper
ator algebras in Athens\n\n\nAbstract\nA exponential Lie group is called (
stably) $C^*$-rigid if it is uniquely determined\, within the class of exp
onential Lie groups\, by the class of isomorphism (Morita equivalence) of
its $C^*$ algebra. We discuss the problem of $C^*$-rigidity of exponential
Lie groups. In particular\, we show that generalized $ax+b$-groups are no
n-rigid\, while nilpotent Lie groups of dimension less than equal to 5 are
stably $C^*$-rigid.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Daws (University of Central Lancashire\, UK)
DTSTART:20230303T150000Z
DTEND:20230303T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/51
DESCRIPTION:Title: Around the Approximation Property for Quantum Groups\nby Ma
tthew Daws (University of Central Lancashire\, UK) as part of Functional a
nalysis and operator algebras in Athens\n\n\nAbstract\nI will introduce wh
at the "approximation property" (AP) is for (locally compact) groups\, and
provide a few applications. I will then talk about how one might give an
analogous definition for (locally compact) quantum groups\, explaining so
me of the needed technology along the way.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavlos Motakis (York University)
DTSTART:20230324T150000Z
DTEND:20230324T170000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/52
DESCRIPTION:Title: Separable spaces of continuous functions as Calkin algebras
\nby Pavlos Motakis (York University) as part of Functional analysis and o
perator algebras in Athens\n\n\nAbstract\nFor a Banach space $X$ denote $\
\mathcal{L}(X) = \\{T:X\\to X\\text{ linear and bounded}\\}$ and $\\mathca
l{K}(X) = \\{T\\in\\mathcal{L}(X): T\\text{ compact}\\}$. The Calkin algeb
ra of $X$ is the Banach algebra $\\mathcal{C}al(X) = \\mathcal{L}(X)/\\mat
hcal{K}(X)$. A question that has gathered attention in recent years is wha
t unital Banach algebras admit representations as Calkin algebras. We dis
cuss developments in this topic as well as a recent contribution\, namely
that for 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://stable.researchseminars.org/talk/AthensFAOA/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandros Eskenazis (Sorbonne\, Fr & Cambridge\, UK)
DTSTART:20230407T140000Z
DTEND:20230407T160000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/53
DESCRIPTION:Title: Discrete logarithmic Sobolev inequalities in Banach spaces\
nby Alexandros Eskenazis (Sorbonne\, Fr & Cambridge\, UK) as part of Funct
ional analysis and operator algebras in Athens\n\n\nAbstract\nWe shall dis
cuss certain aspects of vector-valued harmonic analysis on the discrete hy
percube. After presenting the geometric motivation behind such investigati
ons\, we will survey known results on the Poincaré inequality and Talagra
nd’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://stable.researchseminars.org/talk/AthensFAOA/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petros Valettas (U. Missouri\, USA)
DTSTART:20230519T140000Z
DTEND:20230519T160000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/56
DESCRIPTION:Title: Probabilistic Padé Problems\nby Petros Valettas (U. Missou
ri\, USA) as part of Functional analysis and operator algebras in Athens\n
\n\nAbstract\nIt has been observed\, by Froissart (1969)\, that zeros and
poles of higher order Padé approximants of random perturbations of a dete
rministic Taylor series tend to form unstable pairs. These pairs appear at
loci characteristic of the random part in the coefficients of the Taylor
series. While this phenomenon has only been confirmed experimentally\, it
has been suggested\, and indeed used\, as a noise detection tool. In this
talk we will explain how techniques from high-dimensional probability and
logarithmic potential theory can be melted together to rigorously establis
h and quantify the clustering of zeros in the ``pure noise’’ case\, wh
en the coefficients are drawn according to a distribution with anti-concen
tration properties. \n\nBased on a joint ongoing work with S. Dostoglou (U
niversity of Missouri).\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E.T.A. Kakariadis (Newcastle U.\, UK)
DTSTART:20230331T120000Z
DTEND:20230331T140000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/57
DESCRIPTION:Title: Entropy and phase transitions for KMS-states of Pimsner-type al
gebras\nby E.T.A. Kakariadis (Newcastle U.\, UK) as part of Functional
analysis and operator algebras in Athens\n\n\nAbstract\nThere is a well-d
eveloped theory of Kubo-Martin-Schwinger states (or equilibrium states) fo
r C*-algebras\, which are motivated by the properties of Gibbs states for
finite matrices. They have attracted interest as they provide an invariant
for classification up to equivariant isomorphisms of C*-algebras. There h
as been a growing study of their parametrization in particular for C*-alge
bras coming from Hilbert modules\, which are generalizations of the Toepli
tz and Cuntz algebras. In this talk I will give an overview about the theo
ry of KMS states in this setting and present how the notion of entropy all
ows to identify phase transitions. Time permitting we will discuss how thi
s works for graph algebras and Nica-Pimsner algebras.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sarah Reznikoff (Kansas State U.\, USA)
DTSTART:20230428T140000Z
DTEND:20230428T160000Z
DTSTAMP:20260404T111107Z
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 algebr
as in Athens\n\n\nAbstract\nWe define and discuss the regular ideals of $C
^*$-algebras including the special case of graph algebras\, in particular
properties preserved by quotients of regular ideals. This is joint work w
ith Jonathan Brown\, Adam Fuller\, and David Pitts.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/58/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ebrahim Samei (U. Saskatchewan\, Canada)
DTSTART:20230505T140000Z
DTEND:20230505T160000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/59
DESCRIPTION:Title: New tensor products of C*-algebras and characterization of type
I C*-algebras as rigidly symmetric C*-algebras\nby Ebrahim Samei (U.
Saskatchewan\, Canada) as part of Functional analysis and operator algebra
s in Athens\n\n\nAbstract\nC*-algebras are studied through various tools a
nd techniques including their tensor products. There are several classes
of tensor products that have been considered and studied extensively on C*
-algebras. We introduce a new class of such objects using the theory of co
mplex interpolations on operator spaces. Our construction allows us to pro
duce a continuum family of distinct tensor product of the reduced C*-algeb
ras of nonamenable groups possessing both the rapid decay and Haagerup pro
perty. 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
complete answer to a question of Leptin and Poguntke from 1979 proving tha
t 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 Winnipeg).\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Petrakos (WWU Münster\, Germany)
DTSTART:20230512T140000Z
DTEND:20230512T160000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/60
DESCRIPTION:Title: Dynamical Alternating Groups\nby S. Petrakos (WWU Münster\
, Germany) as part of Functional analysis and operator algebras in Athens\
n\n\nAbstract\nTopological full groups form a very important class of grou
ps arising from\ndynamical systems and\, more generally\, étale groupoids
. Their subgroups\, especially the\nalternating subgroup\, have been prove
n to exhibit various properties\, some of which were\nrarely or never befo
re witnessed. In this talk I will introduce these groups in the dynamical\
nsetting and go through some of the most important past results on the top
ic\, focusing on\nthose of operator-algebraic interest. I will then briefl
y introduce the concept of almost\nfiniteness and present a recent result
obtained in joint work with Petr Naryshkin. We prove\nthat if a subgroup o
f a TFG is amenable and contains the alternating subgroup\, then all its\n
free actions on finite-dimensional compact metrizable spaces are almost fi
nite.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:G. Kopsacheilis (WWU Münster. Germany)
DTSTART:20230526T140000Z
DTEND:20230526T160000Z
DTSTAMP:20260404T111107Z
UID:AthensFAOA/61
DESCRIPTION:Title: A comparison type property for Cartan subalgebras\nby G. Ko
psacheilis (WWU Münster. Germany) as part of Functional analysis and oper
ator algebras in Athens\n\n\nAbstract\nRegularity properties of C*-algebra
s are vital for classification theory. In the C*-setting\, finite nuclear
dimension\, tensorial absorption of the Jiang--Su algebra and strict compa
rison set the stage for Elliott's classification programme\; these propert
ies are known to be tightly related\, as the (to a large extent confirmed)
Toms--Winter conjecture predicts. On the dynamical side\, analogues of th
ese have been introduced for group actions\, and it is not yet quite clear
how these relate to the regularity properties of the crossed product. In
this talk\, we introduce a comparison type property in the context of Cart
an subalgebras and study its relations to regularity properties of the amb
ient C*-algebra\, and of the underlying dynamics\, when the inclusion aris
es from a topological dynamical system. \nThis talk is based on joint work
(in progress) with Wilhelm Winter.\n
LOCATION:https://stable.researchseminars.org/talk/AthensFAOA/61/
END:VEVENT
END:VCALENDAR