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CALSCALE:GREGORIAN
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BEGIN:VEVENT
SUMMARY:Arthur Jaffe (Harvard)
DTSTART:20210608T150000Z
DTEND:20210608T155000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/1
DESCRIPTION:Title:
Remembering the Future\nby Arthur Jaffe (Harvard) as part of Conferenc
e on operator algebras and related topics in Istanbul\, 2021\n\nAbstract:
TBA\n
LOCATION:https://researchseminars.org/talk/Opalg21/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sorin Popa (UCLA)
DTSTART:20210608T160000Z
DTEND:20210608T165000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/2
DESCRIPTION:Title:
On the rigidity of virtual symmetries of II_1 factors\nby Sorin Popa (
UCLA) as part of Conference on operator algebras and related topics in Ist
anbul\, 2021\n\n\nAbstract\nOne of the most fascinating aspects in the ana
lysis of non-commutative spaces (aka von Neumann algebras)\, is the way th
eir building data\, which is often geometric in nature\, impacts on their
generalized (or virtual) symmetry picture. This is particularly the case f
or II_1 factors\, where virtual symmetries are encoded by subfactors of fi
nite Jones index\, a numerical invariant that can be quantized in intrigui
ng ways. I will discuss some results and open problems that illustrate the
unique interplay between analysis and algebra/combinatorics entailed by t
his interdependence\, that's specific to subfactor theory.\n
LOCATION:https://researchseminars.org/talk/Opalg21/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcelo Laca (U Victoria)
DTSTART:20210608T173000Z
DTEND:20210608T181500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/3
DESCRIPTION:Title:
Toeplitz algebras of semigroups\nby Marcelo Laca (U Victoria) as part
of Conference on operator algebras and related topics in Istanbul\, 2021\n
\n\nAbstract\nI will start by reviewing classical work of Coburn\, Douglas
\, and Cuntz about C*-algebras generated by isometries\, and then present
universal models for the Toeplitz algebras of submonoids of groups and for
their boundary quotients\, discussing their uniqueness and simplicity pro
perties. This is recent joint work with Camila F. Sehnem that generalizes
previous results of Nica\, Li\, and Raeburn and myself.\n
LOCATION:https://researchseminars.org/talk/Opalg21/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hans Wenzl (UCSD)
DTSTART:20210608T183000Z
DTEND:20210608T191500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/4
DESCRIPTION:Title:
Subfactors\, Tensor Categories and Module Categories\nby Hans Wenzl (U
CSD) as part of Conference on operator algebras and related topics in Ista
nbul\, 2021\n\n\nAbstract\nWhen Vaughan Jones started to think about the n
otion of an index for subfactors\, the only known examples came from group
s and their representations and from the embedding of groups H < G. In bot
h cases the indices were integers. Vaughan's surprising examples with non-
integer index were later connected to representations of the quantum group
U_q(sl2) and to representations of the loop group LSU(2). This was subseq
uently generalized to the construction of a sequence of subfactors for eve
ry representation of a semisimple Lie algebra.The question remains to cons
truct subfactors corresponding to analogs of subgroups of Lie groups\; in
modern language this amounts to classifying module categories of certain t
ensor categories. Again\, Vaughan made important contributions for solving
the problem for the sl_2 case constructing what is generally referred to
as Goodman-de la Harpe-Jones subfactors. While complete classifications ar
e known for several Lie groupsof small rank\, the general problem is still
far from being solved. We give an overview of the current state of knowle
dge\, and present some explicit examples.\n
LOCATION:https://researchseminars.org/talk/Opalg21/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Florin Radulescu (Univ. Roma)
DTSTART:20210608T193000Z
DTEND:20210608T201500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/5
DESCRIPTION:Title:
Common trends in Operator Algebra and Number Theory\nby Florin Radules
cu (Univ. Roma) as part of Conference on operator algebras and related top
ics in Istanbul\, 2021\n\n\nAbstract\nMany years ago (almost 30) Vaughan J
ones initiated an approach to a new program of understanding of automorphi
c forms as Operator Algebra objects. There are naturally associated $II_1$
factors ( in the free groups factors series) His original motivation was
to understand if Hecke subgroups could be possibly related to a more natur
al construction of non-integer index subfactors in free group factors.. Th
ere is one "mystery trace vector (s)" which one would like to understand\,
and this showed up again in his late work. I will discuss these topics an
d their relations to other problems in number theory that have a natural O
perator Algebra counterpart.\n
LOCATION:https://researchseminars.org/talk/Opalg21/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivan Bardet (Univ. Lyon)
DTSTART:20210609T130000Z
DTEND:20210609T134500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/6
DESCRIPTION:Title:
Approximate tensorization of the relative entropy for noncommuting conditi
onal expectations\nby Ivan Bardet (Univ. Lyon) as part of Conference o
n operator algebras and related topics in Istanbul\, 2021\n\n\nAbstract\nI
will present a new generalisation of the strong subadditivity of the entr
opy to the setting of general conditional expectations onto arbitrary fini
te-dimensional von Neumann algebras. The latter inequality\, which we call
approximate tensorization of the relative entropy\, can be expressed as a
lower bound for the sum of relative entropies between a given density and
its respective projections onto two intersecting von Neumann algebras in
terms of the relative entropy between the same density and its projection
onto an algebra in the intersection\, up to multiplicative and additive co
nstants. In particular\, our inequality reduces to the so-called quasi-fac
torization of the entropy for commuting algebras\, which is a key step in
modern proofs of the logarithmic Sobolev inequality for classical lattice
spin systems.\n
LOCATION:https://researchseminars.org/talk/Opalg21/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ion Nechita (Univ. Touloouse and CNRS)
DTSTART:20210609T140000Z
DTEND:20210609T144500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/7
DESCRIPTION:Title:
Enumerating meanders - three perspectives\nby Ion Nechita (Univ. Toulo
ouse and CNRS) as part of Conference on operator algebras and related topi
cs in Istanbul\, 2021\n\n\nAbstract\nThe problem of enumerating meanders i
s a long-standing open problem in combinatorics. Many different techniques
have been used to provide bounds on the asymptotic growth rate of the num
ber of meanders. Here\, we present some of the old methods and some new on
es\, coming from three (related) points of view. First\, as noted by Fukud
a and Sniady\, meanders appear in relation to the partial transposition op
eration in quantum information theory. A second model for meandric numbers
comes from random matrix theory: we shall review some old models due to d
i Francesco and present some new ones. Finally\, I shall present a joint w
ork with Motohisa Fukuda (arXiv:1609.02756 and arXiv:2103.03615) on a thir
d point of view\, that of non-commutative probability. Using the operation
s of free and boolean moment-cumulant transforms\, we enumerate large sub-
classes of meanders\, generalizing previous work of Goulden\, Nica\, and P
uder.\n
LOCATION:https://researchseminars.org/talk/Opalg21/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alice Guionnet (ENS Lyon)
DTSTART:20210609T150000Z
DTEND:20210609T155000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/8
DESCRIPTION:Title:
Topological expansions\, Random matrices and free probability\nby Alic
e Guionnet (ENS Lyon) as part of Conference on operator algebras and relat
ed topics in Istanbul\, 2021\n\n\nAbstract\nIn this lecture\, I will discu
ss the remarkable connection between random matrices\, the enumeration of
maps and some applications to operator algebras and physics. This talk wil
l be based on joint works with Vaughan Jones and Dima Shlyakhtenko as well
as work in progress with Edouard Maurel Segala.\n
LOCATION:https://researchseminars.org/talk/Opalg21/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gilles Pisier (Texas A&M)
DTSTART:20210609T160000Z
DTEND:20210609T165000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/9
DESCRIPTION:Title:
From injectivity to approximation properties for von Neumann algebras\
nby Gilles Pisier (Texas A&M) as part of Conference on operator algebras a
nd related topics in Istanbul\, 2021\n\n\nAbstract\nA von Neumann algebra
M is called injective if there is a projection P:B(H) -> M with ||P||= 1.
This is the analogue for von Neumann algebras of amenability for discrete
groups\, and it notoriously fails when M = M(F) is the von Neumann algebra
of a non-commutative free group F. We will introduce the class of ''seemi
ngly injective'' von Neumann algebras. This includes M(F). We show that M
is seemingly injective iff it has the (matricial) weak* positive metric ap
proximation property (AP in short). This is parallel to Connes's character
ization of injectivity by the weak* completely positive AP. We show that M
(F) is isomorphic to B(H) as Banach spaces when F is countable. Lastly we
discuss several open questions that might be related to Kazhdan's property
(T) for groups.\n
LOCATION:https://researchseminars.org/talk/Opalg21/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kristan Temme (IBM Research)
DTSTART:20210609T173000Z
DTEND:20210609T181500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/10
DESCRIPTION:by Kristan Temme (IBM Research) as part of Conference on opera
tor algebras and related topics in Istanbul\, 2021\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/Opalg21/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikhil Srivastava (UC Berkeley)
DTSTART:20210609T183000Z
DTEND:20210609T191500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/11
DESCRIPTION:Title: Quantitative Diagonalizability\nby Nikhil Srivastava (UC Berkeley) as
part of Conference on operator algebras and related topics in Istanbul\,
2021\n\n\nAbstract\nA diagonalizable matrix has linearly independent eigen
vectors. Since the set of non diagonalizable matrices has measure zero\, e
very matrix is a limit of diagonalizable matrices. We prove a quantitative
version of this fact: every n x n complex matrix is within distance delta
in the operator norm of a matrix whose eigenvectors have condition number
poly(n)/delta\, confirming a conjecture of E. B. Davies. The proof is bas
ed adding a complex Gaussian perturbation to the matrix and studying its p
seudospectrum. Joint work with J. Banks\, A. Kulkarni\, S. Mukherjee\n
LOCATION:https://researchseminars.org/talk/Opalg21/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anna Jencova (Slovakian Academy of Sciences)
DTSTART:20210610T130000Z
DTEND:20210610T134500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/12
DESCRIPTION:Title: Renyi relative entropies and noncommutative Lp spaces\nby Anna Jencov
a (Slovakian Academy of Sciences) as part of Conference on operator algebr
as and related topics in Istanbul\, 2021\n\n\nAbstract\nThere are several
quantum versions of the Renyi relative entropies\, which are fundamental i
n quantum information theory. Some of these quantities were extended to th
e general context of normal states of a von Neumann algebra. We concentrat
e on the class of sandwiched quantum Renyi relative entropies. We show tha
t this class can be defined in terms of the interpolation Lp spaces due to
Kosaki. We discuss some properties of these quantities\, especially the c
onnection to the Araki relative entropy and the data processing inequality
(monotonicity) with respect to positive unital normal maps. In the second
part of the talk\, it is shown that reversibility of a 2-positive unital
normal map with respect to a set of normal states is characterized by equa
lity in the data processing inequality.The talk is based on the papers A.
Jencova: Renyi relative entropies and noncommutative Lp spaces I and II\,
Annales H. Poincare\, 2018 and 2021 (to appear).\n
LOCATION:https://researchseminars.org/talk/Opalg21/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fabio Cipriani (Politechnic Milano)
DTSTART:20210610T140000Z
DTEND:20210610T144500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/13
DESCRIPTION:Title: KMS Dirichlet forms\, coercivity and superbounded Markovian semigroups\nby Fabio Cipriani (Politechnic Milano) as part of Conference on operato
r algebras and related topics in Istanbul\, 2021\n\n\nAbstract\nWe provide
a new construction of Dirichlet forms on von Neumann algebras associated
to eigenvalues of the modular operator of f.n. non tracial states. We desc
ribe their structure in terms of derivations and prove coercivity bounds\,
from which the spectral growth rate are derived. We also introduce a regu
larizing property of Markovian semigroups (superboundedness) stronger than
hypercontractivity\, in terms of noncommutative Lp(M)spaces. We also prov
e superboundedness for the Markovian semigroups associated to the class of
Dirichlet forms introduced above\, for type I factors M. We then apply th
is tools to provide a general construction of the quantum Ornstein-Uhlembe
ck semigroups of the CCR and some of their non-perturbative deformations.\
n
LOCATION:https://researchseminars.org/talk/Opalg21/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joachim Cuntz (Univ. Muenster)
DTSTART:20210610T150000Z
DTEND:20210610T155000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/14
DESCRIPTION:Title: C*-algebras generated by isometries.\nby Joachim Cuntz (Univ. Muenste
r) as part of Conference on operator algebras and related topics in Istanb
ul\, 2021\n\n\nAbstract\nThe property of an operator s on a Hilbert space
to be isometric can be characterized by the algebraic condition s*s = 1. M
any interesting and important C*-algebras can be generated by isometrie
s or obtained by constructions involving isometries. We give a (partly his
torical) survey of various results in which the author has been involved a
nd which are based on such constructions.\n
LOCATION:https://researchseminars.org/talk/Opalg21/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:George Elliott (Univ. Toronto)
DTSTART:20210610T160000Z
DTEND:20210610T165000Z
DTSTAMP:20260422T212526Z
UID:Opalg21/15
DESCRIPTION:Title: The classification of well-behaved simple C*-algebras\nby George Elli
ott (Univ. Toronto) as part of Conference on operator algebras and related
topics in Istanbul\, 2021\n\n\nAbstract\nA brief survey will be given of
the classification of simple separable amenable C* algebras which are Jian
g-Su stable and (possibly redundant) satisfy the Universal Coefficient The
orem (UCT). There are many examples of such algebras\, but note that\, if
a given simple UCT separable amenable C* algebra is not known to be stable
under tensoring with the Jiang-Su algebra\, this is assured just by tenso
ring it anyway with this algebra. Furthermore\, the invariant can be formu
lates in a way that is insensitive to this operation. (Of course\, it is o
nly complete after tenderization).\n
LOCATION:https://researchseminars.org/talk/Opalg21/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kristin Courtney (Univ. Muenster)
DTSTART:20210610T173000Z
DTEND:20210610T181500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/16
DESCRIPTION:Title: Nuclearity and generalized inductive limits\nby Kristin Courtney (Uni
v. Muenster) as part of Conference on operator algebras and related topics
in Istanbul\, 2021\n\n\nAbstract\nOne of Alain Connes' seminal results es
tablishes that any semi-discrete (or injective or amenable) von Neumann al
gebra can be written as a direct limit of dimensional von Neumann algebras
. In the C*-setting however\, such a concise characterization is not possi
ble: the direct C*-analogue of semi-discreteness is nuclearity\, and most
nuclear C*-algebras do not arise as the direct limits of finite dimensiona
l C*-algebras. Nonetheless\, by generalizing the notion of inductive limit
s of C*-algebras\, Blackadar and Kirchberg were able to characterize quasi
diagonal nuclear C*-algebras as those arising as (generalized) inductive l
imits of finite dimensional C*-algebras. In joint work with Wilhelm Winter
\, we give a further generalization of this construction\, which gives us
a complete characterization of separable nuclear C*-algebras as those aris
ing from a (generalized) inductive limit of finite dimensional C*-algebras
.\n
LOCATION:https://researchseminars.org/talk/Opalg21/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryszard Nest (Univ. Copenhagen)
DTSTART:20210610T183000Z
DTEND:20210610T191500Z
DTSTAMP:20260422T212526Z
UID:Opalg21/17
DESCRIPTION:Title: Projective representations of compact quantum groups and the quantum asse
mbly map\nby Ryszard Nest (Univ. Copenhagen) as part of Conference on
operator algebras and related topics in Istanbul\, 2021\n\n\nAbstract\nThe
torsion phenomena play important role in the construction of the assembly
map in the context of Baum-Connes conjecture. The corresponding case of q
uantum groups is more involved\, since the torsion phenomena are not neces
sarily associated to torsion subgroups.An important role in this context i
s played by projective representations of quantum groups. We will describe
the general structure of projective representations\, associated twisted
group C*-algebras and the related torsion phenomena for compact quantum gr
oups.We will also describe the role that these results play in the context
of the assembly map for compact quantum groups.This is ''work in progress
'' joint with Kenny De Commer and Ruben Martos.\n
LOCATION:https://researchseminars.org/talk/Opalg21/17/
END:VEVENT
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