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BEGIN:VEVENT
SUMMARY:Konrad Aguilar (University of Southern Denmark)
DTSTART;VALUE=DATE-TIME:20200422T190000Z
DTEND;VALUE=DATE-TIME:20200422T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/1
DESCRIPTION:Title:
Quantum metrics on the tensor product of a commutative C*-algebra and an A
F C*-algebra.\nby Konrad Aguilar (University of Southern Denmark) as p
art of NYC noncommutative geometry seminar\n\n\nAbstract\nGiven a compact
metric space X and a unital AF algebra A equipped with a faithful tracial
state\, we place quantum\nmetrics on the tensor product of C(X) and A give
n established quantum metrics on C(X) and A from work with Bice\nand Latre
moliere. We prove the inductive limit of C(X) tensor A given by A is a met
ric limit in the Gromov-Hausdorff\npropinquity. We show that our quantum m
etric is compatible with the tensor product by producing a Leibniz rule on
\nelementary tensors and showing the diameter of our quantum metric on the
tensor product is bounded above the diameter\nof the Cartesian product of
the quantum metric spaces. We provide continuous families of C(X) tensor
A which extends\nour previous results with Latremoliere on UHF algebras.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicola Ciccoli (Università di Perugia)
DTSTART;VALUE=DATE-TIME:20200506T190000Z
DTEND;VALUE=DATE-TIME:20200506T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/2
DESCRIPTION:Title:
Orbit correspondence and groupoid C*-algebras\nby Nicola Ciccoli (Univ
ersità di Perugia) as part of NYC noncommutative geometry seminar\n\n\nAb
stract\nIn those NC C*-algebras arising as quantization of a Poisson manif
old one can try to establish a relation between the symplectic foliation o
f the manifold and the unitary dual of its quantization. This relation is
what goes under the name of orbit correspondence. In the best behaved case
s this correspondence is an homeomorphism. We will review some results on
specific examples\, stressing the use of "groupoid quantization" as a too
l to better understand features of this correspondence.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jim Tao 🇳🇴 (Norwegian University of Science and Technology)
DTSTART;VALUE=DATE-TIME:20200429T190000Z
DTEND;VALUE=DATE-TIME:20200429T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/3
DESCRIPTION:Title:
A twisted local index formula for curved noncommutative two tori\nby J
im Tao 🇳🇴 (Norwegian University of Science and Technology) as part o
f NYC noncommutative geometry seminar\n\n\nAbstract\nWe consider the Dirac
operator of a general metric in the \ncanonical conformal class on the no
ncommutative two torus\, \ntwisted by an idempotent (representing the $K$-
theory class \nof a general noncommutative vector bundle)\, and derive a l
ocal \nformula for the Fredholm index of the twisted Dirac operator. Our \
napproach is based on the McKean-Singer index formula\, and \nexplicit hea
t expansion calculations by making use of Connes' \npseudodifferential cal
culus. As a technical tool\, a new rearrangement \nlemma is proved to hand
le challenges posed by the noncommutativity of \nthe algebra and the prese
nce of an idempotent in the calculations in addition \nto a conformal fact
or. This is joint work with Farzad Fathizadeh and Franz Luef.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Branimir Cacic (University of New Brunswick)
DTSTART;VALUE=DATE-TIME:20200513T190000Z
DTEND;VALUE=DATE-TIME:20200513T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/4
DESCRIPTION:Title:
Gauge theory on quantum principal bundles\nby Branimir Cacic (Universi
ty of New Brunswick) as part of NYC noncommutative geometry seminar\n\n\nA
bstract\nIn this talk\, I’ll give a brief (and somewhat idiosyncratic) i
ntroduction to gauge theory on quantum principal bundles. I’ll give a qu
ick overview of the classical setting and sketch its noncommutative genera
lisation à la Brzeziński–Majid\, Hajac\, et al. Then I’ll revisit th
e notions of principal connection and gauge transformation from the perspe
ctive of recent work by Ć.–Mesland. I'll illustrate these concepts usin
g the irrational rotation algebra as a quantum principal U(1)-bundle over
the circle.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emil V Prodan (Yeshiva University)
DTSTART;VALUE=DATE-TIME:20200603T190000Z
DTEND;VALUE=DATE-TIME:20200603T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/5
DESCRIPTION:Title:
Index theorems in KK-theory\nby Emil V Prodan (Yeshiva University) as
part of NYC noncommutative geometry seminar\n\n\nAbstract\nConsider an ext
ended (Delone) point pattern in the d-dimensional Euclidean space such tha
t each point hosts N degrees of freedom. In many practical applications\,
ranging from quantum materials to meta-materials\, one is interested in th
e collective dynamics of the degrees of freedom hosted by the pattern. As
we shall see\, the generators of any pattern-equivariant dynamics belong t
o a specific C*-algebra\, which in general takes the form of a groupoid al
gebra and\, in more manageable cases\, of crossed products with discrete g
roups. The non-commutative geometry program for the aperiodic patterns con
sists in computing the C*-algebra\, its K-theory and cyclic co-homology\,
as well as establishing index theorems for the K-theory and cyclic co-homo
logy pairings. In these seminars I will describe several interesting cases
where this program has been carried almost entirely. I have a large numbe
r of numerical simulations\, which I will try to use throughout to exempli
fy the power of these methods.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emil V Prodan (Yeshiva University)
DTSTART;VALUE=DATE-TIME:20200520T190000Z
DTEND;VALUE=DATE-TIME:20200520T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/6
DESCRIPTION:Title:
The C*-algebra of equivariant Hamiltonians over point patterns\nby Emi
l V Prodan (Yeshiva University) as part of NYC noncommutative geometry sem
inar\n\n\nAbstract\nConsider an extended (Delone) point pattern in the d-d
imensional Euclidean space such that each point hosts N degrees of freedom
. In many practical applications\, ranging from quantum materials to meta-
materials\, one is interested in the collective dynamics of the degrees of
freedom hosted by the pattern. As we shall see\, the generators of any pa
ttern-equivariant dynamics belong to a specific C*-algebra\, which in gene
ral takes the form of a groupoid algebra and\, in more manageable cases\,
of crossed products with discrete groups. The non-commutative geometry pro
gram for the aperiodic patterns consists in computing the C*-algebra\, its
K-theory and cyclic co-homology\, as well as establishing index theorems
for the K-theory and cyclic co-homology pairings. In these seminars I will
describe several interesting cases where this program has been carried al
most entirely. I have a large number of numerical simulations\, which I wi
ll try to use throughout to exemplify the power of these methods.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emil V Prodan (Yeshiva University)
DTSTART;VALUE=DATE-TIME:20200527T190000Z
DTEND;VALUE=DATE-TIME:20200527T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/7
DESCRIPTION:Title:
Cyclic co-homology\, Fredholm modules\, Kasparov’s generalizations\n
by Emil V Prodan (Yeshiva University) as part of NYC noncommutative geomet
ry seminar\n\n\nAbstract\nConsider an extended (Delone) point pattern in t
he d-dimensional Euclidean space such that each point hosts N degrees of f
reedom. In many practical applications\, ranging from quantum materials to
meta-materials\, one is interested in the collective dynamics of the degr
ees of freedom hosted by the pattern. As we shall see\, the generators of
any pattern-equivariant dynamics belong to a specific C*-algebra\, which i
n general takes the form of a groupoid algebra and\, in more manageable ca
ses\, of crossed products with discrete groups. The non-commutative geomet
ry program for the aperiodic patterns consists in computing the C*-algebra
\, its K-theory and cyclic co-homology\, as well as establishing index the
orems for the K-theory and cyclic co-homology pairings. In these seminars
I will describe several interesting cases where this program has been carr
ied almost entirely. I have a large number of numerical simulations\, whic
h I will try to use throughout to exemplify the power of these methods.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Menevse Eryuzlu (Arizona State University)
DTSTART;VALUE=DATE-TIME:20200610T190000Z
DTEND;VALUE=DATE-TIME:20200610T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/8
DESCRIPTION:Title:
Enchilada Categories\nby Menevse Eryuzlu (Arizona State University) as
part of NYC noncommutative geometry seminar\n\n\nAbstract\nMuhly and Sole
l developed a notion of Morita equivalence for C*-correspondences\, and th
ey \nproved a very important result: If two injective C*-correspondences
are Morita equivalent then the corresponding Cuntz-Pimsner algebras are Mo
rita equivalent in the sense of Rieffel. \nInstead of proving it directly\
, we build a functor that will give us the result of Muhly and Solel\, \ni
n fact a more generalized version of their result\, as a special case.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sara Azzali (Universität Hamburg)
DTSTART;VALUE=DATE-TIME:20200617T190000Z
DTEND;VALUE=DATE-TIME:20200617T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/9
DESCRIPTION:Title:
KK-theory with real coefficients\, traces\, and discrete group actions
\nby Sara Azzali (Universität Hamburg) as part of NYC noncommutative geom
etry seminar\n\n\nAbstract\nThe groups of KK-theory were introduced by Kas
parov in the 1980’s and have important applications to many geometric an
d topological problems which are tackled by C*-algebraic techniques. \n\nI
n this talk\, we investigate KK-theory groups with coefficients in $\\math
bb R$. By construction\, the adding of real coefficients provides natural
receptacles for classes coming from traces on $C^*$-algebras. \nWe focus o
n applications to the study of discrete groups actions on $C^*$-algebras.
\nWe show that in equivariant KK-theory with coefficients one can "localiz
e at the unit element“ of the discrete group\, and this procedure has in
teresting consequences on the Baum–Connes isomorphism conjecture.\nBased
on joint works with Paolo Antonini and Georges Skandalis.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jianchao Wu (Texas A & M)
DTSTART;VALUE=DATE-TIME:20200624T190000Z
DTEND;VALUE=DATE-TIME:20200624T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/10
DESCRIPTION:Title: The Novikov conjecture\, groups of diffeomorphisms\, and infinite dimensi
onal nonpositively curved spaces\nby Jianchao Wu (Texas A & M) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nThe rational strong
Novikov conjecture is a prominent problem in noncommutative geometry. It
implies deep conjectures in topology and differential geometry such as the
(classical) Novikov conjecture on higher signatures and the Gromov-Lawson
conjecture on positive scalar curvature. Using C*-algebraic and K-theoret
ic tools\, we prove that the rational strong Novikov conjecture holds for
geometrically discrete subgroups of the group of volume preserving diffeom
orphisms of any closed smooth manifold. The crucial geometric property of
these groups that we exploit is the fact that they admit isometric and pro
per actions on a type of infinite-dimensional symmetric space of nonpositi
ve curvature called the space of $L^2$-Riemannian metrics. In fact\, our r
esult holds for any discrete group admitting an isometric and proper actio
n on a (possibly infinite-dimensional) nonpositively curved space that we
call an admissible Hilbert-Hadamard space\; thus our result partially exte
nds earlier ones of Kasparov and Higson-Kasparov. This is joint work with
Sherry Gong and Guoliang Yu.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chris Bruce (Queen Mary University of London)
DTSTART;VALUE=DATE-TIME:20200708T190000Z
DTEND;VALUE=DATE-TIME:20200708T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/11
DESCRIPTION:Title: C*-algebras from actions of congruence monoids\nby Chris Bruce (Queen
Mary University of London) as part of NYC noncommutative geometry seminar
\n\n\nAbstract\nI will give an overview of recent results for semigroup C*
-algebras associated with number fields. These results are already interes
ting in the case where the field is the rational numbers\, and I will focu
s mostly on this case to make everything more explicit and accessible.\nC*
-algebras of full ax+b-semigroups over rings of algebraic integers were fi
rst studied by Cuntz\, Deninger\, and Laca\; their construction has since
been generalized by considering actions of congruence monoids. Semigroup C
*-algebras obtained this way provide an example class of unital\, separabl
e\, nuclear\, strongly purely infinite C*-algebras which\, in many cases\,
completely characterize the initial number-theoretic data. They also carr
y canonical time evolutions\, and the associated C*-dynamical systems exhi
bit intriguing phenomena. For instance\, the striking similarity between t
he K-theory formula and the parameterization space for the low temperature
KMS states\, observed by Cuntz in the case of the full ax+b-semigroup\, p
ersists in the more general setting.\nPart of this work is joint with Xin
Li\, and part is joint with Marcelo Laca and Takuya Takeishi.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Raphael Ponge (Sichuan University)
DTSTART;VALUE=DATE-TIME:20200715T190000Z
DTEND;VALUE=DATE-TIME:20200715T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/12
DESCRIPTION:Title: Analysis on curved noncommutative tori\nby Raphael Ponge (Sichuan Uni
versity) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nNon
commutative tori are important examples of noncommutative spaces. Followin
g seminal work by Connes-Tretkoff\, Connes-Moscovici\, Fathizadeh-Khalkhal
i\, and others a differential geometric apparatus on NC tori is currently
being built. So far the main focus has been mostly on conformal deformatio
n of the (flat) Euclidean metric or product of such metrics. \n\nThis talk
will report on ongoing work to deal with general Riemannian metrics on NC
tori (in the sense of Jonathan Rosenberg). Results include local and micr
olocal Weyl laws\, Gauss-Bonnet theorems metrics\, and local index formul
as.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tushar Das (University of Wisconsin - La Crosse)
DTSTART;VALUE=DATE-TIME:20200805T190000Z
DTEND;VALUE=DATE-TIME:20200805T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/13
DESCRIPTION:Title: The Varieties of Discrete Experience\, and Other Tales of Isometric Actio
ns on Gromov Hyperbolic Metric Spaces\nby Tushar Das (University of Wi
sconsin - La Crosse) as part of NYC noncommutative geometry seminar\n\n\nA
bstract\nWe survey joint work with David Simmons and Mariusz Urbanski that
explores extensions of the classical theory of Kleinian groups acting on
a finite-dimensional hyperbolic space to analogous actions on hyperbolic m
etric spaces in the sense of Gromov\, a broad class of spaces which includ
es infinite-dimensional rank one symmetric spaces of noncompact type and m
uch more!\n\nSeveral phenomena induced by greater degrees of freedom than
in finite dimensions (e.g. the different shades of discreteness alluded to
in the title) introduce new delicacies and thereby uncover fresh seams th
at await investigation. The talk is aimed at students and beginners who ar
e unencumbered by the wisdom of experts and others tragically burdened by
knowing too much. Being a novice\, any help from the audience in generatin
g new questions will be graciously accepted.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anna Duwenig (University of Wollongong)
DTSTART;VALUE=DATE-TIME:20200701T190000Z
DTEND;VALUE=DATE-TIME:20200701T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/14
DESCRIPTION:Title: Non-commutative Poincaré Duality of the irrational rotation algebra\
nby Anna Duwenig (University of Wollongong) as part of NYC noncommutative
geometry seminar\n\n\nAbstract\nThe irrational rotation algebra is known t
o be self-dual in a KK-theoretic sense. The required K-homology fundamenta
l class was constructed by Connes out of the Dolbeault operator on the 2-t
orus\, but there has not been an explicit description of the dual element.
In this talk\, I will geometrically construct that K-theory class by usin
g a pair of transverse Kronecker flows on the 2-torus. This is based on jo
int work with my PhD advisor\, Heath Emerson.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Haluk Sengun (University of Sheffield)
DTSTART;VALUE=DATE-TIME:20200722T190000Z
DTEND;VALUE=DATE-TIME:20200722T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/15
DESCRIPTION:Title: Selberg's Trace Formula in operator K-theory\nby Haluk Sengun (Univer
sity of Sheffield) as part of NYC noncommutative geometry seminar\n\n\nAbs
tract\nSelberg introduced his celebrated trace formula in 1956. Since\nthe
n\, the trace formula has become an indispensable tool in number\ntheory\,
with spectacular applications to the Langlands program. After an\nexposit
ion of the trace formula\, I will present an identity in the\nsetting of K
-theory of group C*-algebras that is an analogue of the\ntrace formula. Ti
me remaining\, I will exhibit how one can derive the\nindex theoretic vers
ion of the trace formula (due to Barbasch and\nMoscovici) from our identit
y via the theory of higher indices.\n\nThis is joint work with Bram Meslan
d (Leiden) and Hang Wang (Shanghai).\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jerry Kaminker (UC Davis)
DTSTART;VALUE=DATE-TIME:20200729T190000Z
DTEND;VALUE=DATE-TIME:20200729T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/16
DESCRIPTION:Title: Odd analytic differential K-homology\nby Jerry Kaminker (UC Davis) as
part of NYC noncommutative geometry seminar\n\n\nAbstract\nDifferential K
-theory can be viewed as K-theory for vector bundles with connection. We a
re\ndeveloping a dual version in the the Brown-Douglas-Fillmore setting of
K-homology. The\nrole of a connection is played by a projection. Our goal
is to obtain secondary invariants for\npairs of projections that yield eq
uivalent Toeplitz extensions. The talk will include a general discussion o
f differential K-theory. This is joint work with Xiang Tang.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:John Quigg (Arizona State University)
DTSTART;VALUE=DATE-TIME:20200819T190000Z
DTEND;VALUE=DATE-TIME:20200819T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/17
DESCRIPTION:Title: Baum-Connes\, coactions\, and the Tilde Problem\nby John Quigg (Arizo
na State University) as part of NYC noncommutative geometry seminar\n\n\nA
bstract\nTrouble with the Baum-Connes Conjecture (with coefficients) can i
n some way be blamed upon the existence of groups for which the reduced-cr
ossed-product functor is not exact. The full crossed product is exact but
doesn't fix the conjecture. Efforts to fix the conjecture have focused upo
n the ``minimal exact crossed product''\, whose existence is known through
abstract nonsense\, but a construction remains elusive. Baum\, Guentner\,
and Willett propose a candidate formed in part by tensoring with a fixed
action. Our contribution to the [BGW] ``exotic crossed product'' program i
nvolves composing the full crossed product with coaction functors\, hoping
that the shift to coactions will add new insights. In particular\, we rep
lace the [BGW] candidate by tensoring with a fixed coaction. For a long ti
me we had a hard time proving that our functor is exact. The ``natural'' a
pproach involves embedding into ``tilde multiplier algebras'' (which I'll
define in the talk). But we can't see how to prove that this gives an exac
t functor\, and we call this the Tilde Problem. To get around this\, we in
itially proved exactness of our coaction functor another --- extremely uns
atisfying --- way: a long odyssey through equivariant C*-correspondences\,
``natural'' Morita equivalence\, crossed-product duality\, and --- the fi
nal humiliation --- appealing to exactness of the [BGW] crossed-product fu
nctor itself\, completely thwarting our goal of doing everything within th
e realm of coactions. Fortunately\, we recently saw how to use our incompl
ete knowledge of the tilde functor to prove exactness of our coaction func
tor.\nThis is joint work with Steve Kaliszewski and Magnus Landstad.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robin Deeley (University of Colorado\, Boulder)
DTSTART;VALUE=DATE-TIME:20200812T190000Z
DTEND;VALUE=DATE-TIME:20200812T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/18
DESCRIPTION:Title: Minimal dynamical systems with prescribed K-theory\nby Robin Deeley (
University of Colorado\, Boulder) as part of NYC noncommutative geometry s
eminar\n\n\nAbstract\nI will speak about joint work in progress with Ian P
utnam and Karen Strung. The goal of the project is to study the existence
of minimal homeomorphisms on compact metric spaces. In particular\, I will
discuss partial results related to the following question: What is the ra
nge of the K-theory (or more generally the Elliott invariant) for minimal
crossed products? Our approach to this question is based on the systematic
construction of minimal homeomorphisms with prescribed K-theoretic proper
ties.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anton Yu. Savin (Peoples' Friendship University\, Moscow)
DTSTART;VALUE=DATE-TIME:20200826T190000Z
DTEND;VALUE=DATE-TIME:20200826T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/19
DESCRIPTION:Title: A local index formula for metaplectic operators\nby Anton Yu. Savin (
Peoples' Friendship University\, Moscow) as part of NYC noncommutative geo
metry seminar\n\n\nAbstract\nLet A be the algebra of unitary operators act
ing in $H=L_2(R^n)$ and generated by translations\, orthogonal transformat
ions\, products with exponentials $e^{ikx}$\nand fractional Fourier transf
orms. Equivalently\, A is the algebra generated by quantizations of isomet
ric affine canonical transformations in $T^*R^n$. We show that the well-kn
own index one operator in $R^n$ (which is obtained from the creation and a
nnihilation operators\, see Higson-Kasparov-Trout 1998) denoted by D defin
es a spectral triple (A\,H\,D) in the sense of Connes. Our main result is
an explicit formula for the Connes--Moscovici residue cocycle for this spe
ctral triple. For the subalgebra in A generated by translations and expon
entials\, this gives a local index formula for noncommutative tori. \nThis
is joint work with Elmar Schrohe (Hannover)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pierre Clare (William & Mary)
DTSTART;VALUE=DATE-TIME:20201007T190000Z
DTEND;VALUE=DATE-TIME:20201007T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/20
DESCRIPTION:Title: Essential representations of real reductive groups\nby Pierre Clare (
William & Mary) as part of NYC noncommutative geometry seminar\n\n\nAbstra
ct\nThe tempered dual of a real reductive group G equipped with the Fell\n
topology identifies with the space of irreducible representations of the\n
reduced C*-algebra of G. The Connes-Kasparov isomorphism allows to\ncomput
e the K-theory of this C*-algebra by using the index theory of\nDirac-type
operators on the symmetric space G/K. The goal of the work\npresented her
e (joint with N. Higson\, Y. Song and X. Tang) is to provide\na representa
tion-theoretic approach to this isomorphism. We will\ndescribe the structu
re of the reduced C*-algebra up to Morita\nequivalence and characterize re
presentations that contribute to the\nK-theory in terms of Dirac cohomolog
y.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mahya Ghandehari (University of Delaware)
DTSTART;VALUE=DATE-TIME:20200916T190000Z
DTEND;VALUE=DATE-TIME:20200916T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/21
DESCRIPTION:Title: Fourier algebras of the group of $\\mathbb{R}$-affine transformations and
a dual convolution\nby Mahya Ghandehari (University of Delaware) as p
art of NYC noncommutative geometry seminar\n\n\nAbstract\nA major trend in
Non-commutative Harmonic Analysis is to investigate function spaces relat
ed to Fourier analysis (and representation theory) of non-abelian groups.\
n\nThe Fourier algebra\, which is associated with the left regular represe
ntation of the ambient group\, is an important example of such function sp
aces. This function algebra encodes the properties of the group in various
ways\; for instance the existence of derivations on this algebra translat
es into information about the commutativity of the group itself. \n\n\n\nI
n this talk\, we investigate the Fourier algebra of the group of $\\mathbb
{R}$-affine transformations. In particular\, we discuss the non-commutati
ve Fourier transform for this group\, and provide an explicit formula for
the convolution product on the ``dual side'' of this transform. As an app
lication of this new dual convolution product\, we show an easy dual formu
lation for (the only known) symmetric derivative on the Fourier algebra of
the group. \n\n\n\nThis talk is mainly based on joint articles with Y. C
hoi.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Toke Meier Carlsen (University of the Faroe Islands)
DTSTART;VALUE=DATE-TIME:20200902T190000Z
DTEND;VALUE=DATE-TIME:20200902T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/22
DESCRIPTION:Title: Cuntz-Krieger algebras\, topological Markov shifts and groupoids\nby
Toke Meier Carlsen (University of the Faroe Islands) as part of NYC noncom
mutative geometry seminar\n\n\nAbstract\nIt is well-known that there is a
strong connection between Cuntz-Krieger algebras and a certain type of shi
fts of finite type called topological Markov shifts. Recently\, it has bee
n discovered that topological Markov shifts can be recovered up to differe
nt kinds of equivalence from the corresponding Cuntz-Krieger algebras.\n\n
I will give an overview of these results and explain how groupoids can be
used to prove and generalise them.\n\nThe talk will primarily be based on
the following papers.\n\nK. Matsumoto: "Orbit equivalence of topological M
arkov shifts and Cuntz-Krieger algebras".\n\nK. Matsumoto: "Continuous orb
it equivalence\, flow equivalence of Markov shifts and circle actions on C
untz–Krieger algebras".\n\nK. Matsumoto and H. Matui: "Continuous orbit
equivalence of topological Markov shifts and Cuntz–Krieger algebras".\n\
nT. M. Carlsen\, S. Eilers\, E. Ortega\, and G. Restorff: "Flow equivalenc
e and orbit equivalence for shifts of finite type and isomorphism of their
groupoids".\n\nT. M. Carlsen and J. Rout: "Diagonal-preserving gauge-inva
riant isomorphisms of\ngraph C*-algebras".\n\nT. M. Carlsen\, E. Ruiz\, A.
Sims\, and M. Tomforde: "Reconstruction of groupoids and C*-rigidity of d
ynamical systems".\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrey Glubokov (Ave Maria University\, Florida)
DTSTART;VALUE=DATE-TIME:20200909T190000Z
DTEND;VALUE=DATE-TIME:20200909T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/23
DESCRIPTION:Title: Cluster Algebras and their applications to Index Theorem\nby Andrey G
lubokov (Ave Maria University\, Florida) as part of NYC noncommutative geo
metry seminar\n\n\nAbstract\nCluster Algebras were introduced in 2000 by F
omin and Zelevinsky and since then their applications were developed in ma
ny areas of mathematics and theoretical physics. We would like to introduc
e some of the Cluster Algebras and to explore the connections between them
and Jones Index Theorem.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sayan Chakraborty (Indian Statistical Institute\, Kolkata)
DTSTART;VALUE=DATE-TIME:20200923T190000Z
DTEND;VALUE=DATE-TIME:20200923T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/24
DESCRIPTION:Title: Morita equivalence of noncommutative orbifolds\nby Sayan Chakraborty
(Indian Statistical Institute\, Kolkata) as part of NYC noncommutative geo
metry seminar\n\n\nAbstract\nWe consider group actions on noncommutative t
ori and study the corresponding 'noncommutative quotients' as crossed prod
uct C*-algebras. We will show how such actions appear naturally and also g
ive Morita equivalence classes of such crossed products. The results are a
n extension of similar results obtained by Elliott and Rieffiel for the ca
se of noncommutative tori.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cristian Ivanescu (MacEwan University\, Alberta)
DTSTART;VALUE=DATE-TIME:20200930T190000Z
DTEND;VALUE=DATE-TIME:20200930T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/25
DESCRIPTION:Title: The Cuntz semigroup and the classification of separable amenable C*-algeb
ras\nby Cristian Ivanescu (MacEwan University\, Alberta) as part of NY
C noncommutative geometry seminar\n\n\nAbstract\nNuclear C*-algebras (or e
quivalently amenable C*-algebras) are a large class of C*-algebras amenabl
e to study due to their finite-dimensional approximation property. Z-stabl
e C*-algebras are C*-algebras that satisfy a regularity property which pro
ves fundamental for the known classification results that we know so far.
In this talk\, I will describe the Cuntz semigroup and its properties. Evi
dence that the Cuntz semigroup can be used as an invariant to classify ame
nable C*-algebras will be discussed.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxim Braverman (Northeastern University)
DTSTART;VALUE=DATE-TIME:20201014T190000Z
DTEND;VALUE=DATE-TIME:20201014T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/26
DESCRIPTION:Title: Spectral Flow of Toeplitz operators and bulk-edge correspondence\nby
Maxim Braverman (Northeastern University) as part of NYC noncommutative ge
ometry seminar\n\n\nAbstract\nWe show that the (graded) spectral flow of a
family of Toeplitz operators on a complete Riemannian manifold is equal t
o the index of a certain Callias-type operator. When the dimension of the
manifold is even this leads to a cohomological formula for the spectral fl
ow. As an application\, we compute the spectral flow of a family of Toepli
tz operators on a strongly pseudoconvex domain in $\\mathbb{C}^n$. This re
sult is similar to the Boutet de Monvel's computation of the index of a si
ngle Toeplitz operator on a strongly pseudoconvex domain. Finally\, we sho
w that the bulk-boundary correspondence in a tight-binding model of topolo
gical insulators is a special case of our results. At the end I will expla
in KK-theoretical extension of the main theaorem to families of Toeplitz o
perators parametrized by an arbitrary compact manifold\, obtained by Koen
van den Dungen.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andre Kornell (Tulane University)
DTSTART;VALUE=DATE-TIME:20201118T200000Z
DTEND;VALUE=DATE-TIME:20201118T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/27
DESCRIPTION:Title: Finite quantum structures\nby Andre Kornell (Tulane University) as pa
rt of NYC noncommutative geometry seminar\n\n\nAbstract\nWeaver's quantum
relations provide a basis for a unified understanding of several classes o
f quantum structures. In full generality\, quantum relations are defined f
or arbitrary von Neumann algebras\, but to simplify the discussion\, this
talk will focus on finite-dimensional von Neumann algebras. I will talk ab
out quantum graphs\, quantum posets\, quantum groups\, quantum metric spac
es and quantum families of permutations and of graph isomorphisms. I will
emphasize that each of these quantum generalizations can be motivated from
Birkhoff and von Neumann's original conception of quantum logic as the lo
gic of closed subspaces of a Hilbert space. (arXiv:2004.04377)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabor Etesi (Budapest University of Technology and Economics)
DTSTART;VALUE=DATE-TIME:20201021T190000Z
DTEND;VALUE=DATE-TIME:20201021T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/28
DESCRIPTION:Title: The universal von Neumann algebra of smooth 4-manifolds with an applicati
on to gravity\nby Gabor Etesi (Budapest University of Technology and E
conomics) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nMa
king use of its smooth structure only\, out of a connected\noriented smoot
h $4$-manifold a von Neumann algebra is constructed. As a\nspecial four di
mensional phenomenon this von Neumann algebra is\napproximated by algebrai
c (i.e.\, formal) curvature tensors of the\nunderlying $4$-manifold and th
e von Neumann algebra itself is a\nhyperfinite factor of ${\\rm II}_1$ typ
e hence is unique up to abstract\nisomorphisms of von Neumann algebras. Ne
vertheless over a fixed\n$4$-manifold this von Neumann algebra admits a re
presentation on a Hilbert\nspace such that its unitary equivalence class i
s preserved by\norientation-preserving diffeomorphisms. Consequently the M
urray--von\nNeumann coupling constant of this representation is well-defin
ed and gives\nrise to a new and computable real-valued smooth $4$-manifold
invariant: In\nan appropriate sense this invariant along all simply conne
cted closed\n$4$-manifolds is generated by its surely non-trivial value on
\n${\\mathbb C}P^2$ (with its standard smooth structure) alone.\n\nIn the
second half of the seminar (i.e. if time remains) some consequences\nof th
is construction for quantum gravity are also discussed. Namely\nreversing
the construction by starting not with a particular smooth\n$4$-manifold bu
t with the unique hyperfinite ${\\rm II}_1$ factor\, a\nconceptually simpl
e but manifestly four dimensional\, covariant\,\nnon-perturbative and genu
inely quantum theory is introduced whose\nclassical limit is general relat
ivity in an appropriate sense. Therefore\nit is reasonable to consider it
as a sort of quantum theory of gravity. In\nthis model\, among other inter
esting things\, the observed positive but\nsmall value of the cosmological
constant acquires a natural explanation.\n\nReference\n\n1. G. Etesi: The
universal von Neumann algebra of smooth four-manifolds\,\nto appear in Ad
v. Theor. Math. Phys.\, arXiv: 1712.01828 [math-ph]\;\n\n2. G. Etesi: Grav
ity as a four dimensional algebraic quantum field theory\,\nAdv. Theor. Ma
th. Phys. 20\, 1049-1082 (2016)\, arXiv: 1402.5658 [hep-th].\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valentin Deaconu (University of Nevada\, Reno)
DTSTART;VALUE=DATE-TIME:20201028T190000Z
DTEND;VALUE=DATE-TIME:20201028T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/29
DESCRIPTION:Title: Symmetries of the $C^∗$-algebra of a vector bundle\nby Valentin Dea
conu (University of Nevada\, Reno) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nWe consider $C^*$-algebras constructed from compact
group actions on complex vector bundles $E\\to X$ endowed with a Hermiti
an metric. An action of $G$ by isometries on $E\\to X$ induces an actio
n on the $C^*$-correspondence $\\Gamma(E)$ over $C(X)$ consisting of con
tinuous sections\, and on the associated Cuntz-Pimsner algebra $\\mathcal{
O}_E$\, so we can study the crossed product $\\mathcal{O}_E\\rtimes G$.\n\
nIf the action is free and rank $E=n$\, then we prove that $\\mathcal{O}_
E\\rtimes G$ is \nMorita-Rieffel equivalent to a field of Cuntz algebras $
\\mathcal O_n$ over the orbit space $X/G$.\n\nIf the action is fiberwise
\, then $\\mathcal{O}_E\\rtimes G$ becomes a continuous field of crossed p
roducts $\\mathcal{O}_n\\rtimes G$. For transitive actions\, we show that
\n$\\mathcal{O}_E\\rtimes G$ is Morita-Rieffel equivalent to a graph $C^*
$-algebra.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Erik van Erp (Dartmouth College)
DTSTART;VALUE=DATE-TIME:20201104T200000Z
DTEND;VALUE=DATE-TIME:20201104T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/30
DESCRIPTION:Title: The Heisenberg calculus\, index theory\, and cyclic cohomology\nby Er
ik van Erp (Dartmouth College) as part of NYC noncommutative geometry semi
nar\n\n\nAbstract\nOn a compact contact manifold\, a pseudodifferential op
erator with an invertible symbol in the Heisenberg calculus is a hypoellip
tic Fredholm operator. Its symbol determines an element in the K-theory of
the noncommutative algebra of Heisenberg symbols. In joint work with Alex
ander Gorokhovksy\, we construct a cyclic cocycle which\, when paired with
the Connes-Chern character of the principal Heisenberg symbol\, calculate
s the index.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nik Weaver (Washington University)
DTSTART;VALUE=DATE-TIME:20201111T200000Z
DTEND;VALUE=DATE-TIME:20201111T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/31
DESCRIPTION:Title: Quantum graph theory\nby Nik Weaver (Washington University) as part o
f NYC noncommutative geometry seminar\n\n\nAbstract\nIn recent years opera
tor systems --- unital self-adjoint spaces of operators --- have come to b
e seen as "quantum" graphs. The original motivation for this analogy came
from quantum error correction\, but the subject has developed a life of i
ts own. I will discuss quantum Ramsey theory\, the quantum Turan problem\
, and quantum chromatic number.\n\nI will mostly stick to the finite dimen
sional setting\, so there will be few prerequisites beyond linear algebra
over the complex numbers.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bram Mesland (Leiden University)
DTSTART;VALUE=DATE-TIME:20201125T200000Z
DTEND;VALUE=DATE-TIME:20201125T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/32
DESCRIPTION:Title: Gabor frames and Wannier bases from groupoid Morita equivalences\nby
Bram Mesland (Leiden University) as part of NYC noncommutative geometry se
minar\n\n\nAbstract\nA key question in Gabor analysis is the reconstructio
n of elements in a Hilbert space \nvia a Gabor frame. Gabor frames arise f
rom a finite set of vectors acted upon by a canonically defined \nset of o
perators (typically translation and modulation). \nThis data is often conv
eniently encoded in the algebraic structure of a groupoid. In this talk we
will discuss how the natural notion of Morita equivalence of groupoids gi
ves rise to Gabor frames for the Hilbert space localisation of \nthe Morit
a equivalence bimodule of the reduced groupoid $C^*$-algebras. For finitel
y generated and projective submodules\, we show these Gabor frames are ort
honormal \nbases if and only if the module is free. \nIf time allows\, we
will discuss an application of this result to spectral subspaces of Schroe
dinger operators with atomic potentials supported on (aperiodic) Delone s
ets.\n\nThis is joint work with Chris Bourne (Tohoku University)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Jekel (UC San Diego)
DTSTART;VALUE=DATE-TIME:20201202T200000Z
DTEND;VALUE=DATE-TIME:20201202T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/33
DESCRIPTION:Title: Non-commutative transport of measure\nby David Jekel (UC San Diego) a
s part of NYC noncommutative geometry seminar\n\n\nAbstract\nGiven self-ad
joint operators $X_1\, \\dots\, X_d$ and $Y_1\, \\dots\, Y_d$\, it is diff
icult to tell when the von Neumann algebra generated by the $X_j$'s and $Y
_j$'s are isomorphic. Viewing the operators as non-commutative random var
iables\, the isomorphism of von Neumann algebras is equivalent to the exis
tence of a non-commutative function that will push forward the non-commuta
tive probability distribution of $X = (X_1\,\\dots\,X_d)$ to that of $Y =(
Y_1\,\\dots\,Y_d)$. It was proved by Guionnet\, Shlyakhtenko\, and Dabrow
ski that certain nice non-commutative probability distributions known as f
ree Gibbs laws can be transported to the non-commutative Gaussian distribu
tion\, and thus the associated von Neumann algebras are all isomorphic. M
ore recently\, we have shown that this transport can be done in a lower tr
iangular manner\, so that the von Neumann algebra generated by $X_1\, \\do
ts\, X_k$ is mapped to the von Neumann algebra generated by $Y_1\, \\dots\
, Y_k$ for $k = 1\, \\dots\, d$. Furthermore\, this transport arises in a
natural way as the large-$n$ limit of classical transport of measure for
random variables in the space of $d$-tuples $n \\times n$ matrices that ap
proximate $(X_1\,\\dots\,X_d)$ as $n \\to \\infty$.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Goncalo Tabuada (University of Warwick)
DTSTART;VALUE=DATE-TIME:20210120T160000Z
DTEND;VALUE=DATE-TIME:20210120T170000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/34
DESCRIPTION:Title: Noncommutative Weil conjecture\nby Goncalo Tabuada (University of War
wick) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nThe We
il conjectures (proved by Deligne in the 70's) played a key role in the de
velopment of modern algebraic geometry. In this talk I will extend the Wei
l conjectures from the realm of algebraic geometry to the broad noncommuta
tive setting of differential graded categories and describe some of its nu
merous applications.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Kennedy (University of Waterloo)
DTSTART;VALUE=DATE-TIME:20210127T200000Z
DTEND;VALUE=DATE-TIME:20210127T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/35
DESCRIPTION:Title: Amenability\, proximality and higher order syndeticity\nby Matthew Ke
nnedy (University of Waterloo) as part of NYC noncommutative geometry semi
nar\n\n\nAbstract\nI will present new descriptions of some universal flows
associated to a discrete group\, obtained using what we view as a kind of
"topological Furstenberg correspondence." The descriptions are algebraic
and relatively concrete\, involving subsets of the group satisfying a hig
her order notion of syndeticity. We utilize them to establish new necessar
y and sufficient conditions for strong amenability and amenability. Furthe
rmore\, utilizing similar techniques\, we obtain a characterization of "de
nse orbit sets\," answering a question of Glasner\, Tsankov\, Weiss and Zu
cker. Throughout the talk\, I will discuss connections to operator algebra
s.\n\nThis is joint work with Sven Raum and Guy Salomon.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vrej Zarikian (U.S. Naval Academy)
DTSTART;VALUE=DATE-TIME:20210203T200000Z
DTEND;VALUE=DATE-TIME:20210203T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/36
DESCRIPTION:Title: Unique Extension Properties for C*-Inclusions\nby Vrej Zarikian (U.S.
Naval Academy) as part of NYC noncommutative geometry seminar\n\n\nAbstra
ct\nLet $\\mathcal{A} \\subseteq \\mathcal{B}$ be a $C^*$-inclusion\, i.e.
\, an inclusion of unital $C^*$-algebras with the same unit. Structural pr
operties of the inclusion are often reflected by the fact that certain fam
ilies of UCP (unital completely positive) maps on $\\mathcal{A}$ extend un
iquely to UCP maps on $\\mathcal{B}$. In particular\, depending on the str
ucture of $\\mathcal{A} \\subseteq \\mathcal{B}$\, it could be the case th
at\n\ni. every pure state on $\\mathcal{A}$ extends uniquely to a pure sta
te on $\\mathcal{B}$ (i.e.\, $\\mathcal{A} \\subseteq \\mathcal{B}$ has th
e pure extension property)\;\n\nii. a weak* dense set of pure states on $\
\mathcal{A}$ extend uniquely to pure states on $\\mathcal{B}$ (i.e.\, $\\m
athcal{A} \\subseteq \\mathcal{B}$ has the almost extension property)\;\n\
niii. the identity map $\\operatorname{id}:\\mathcal{A} \\to \\mathcal{A}$
extends uniquely to a UCP map $E:\\mathcal{B} \\to \\mathcal{A}$ (i.e.\,
$\\mathcal{A} \\subseteq \\mathcal{B}$ has a unique conditional expectatio
n)\;\n\niv. the identity map $\\operatorname{id}:\\mathcal{A} \\to \\mathc
al{A}$ extends uniquely to a UCP map $\\theta:\\mathcal{B} \\to I(\\mathca
l{A})$\, where $I(\\mathcal{A})$ is the injective envelope of $\\mathcal{A
}$ (i.e.\, $\\mathcal{A} \\subseteq \\mathcal{B}$ has a unique pseudo-expe
ctation).\n\nIn this talk\, we explore properties (i)-(iv) above\, with a
special emphasis on abelian inclusions $C(X) \\subseteq C(Y)$ and inclusio
ns $\\mathcal{A} \\subseteq \\mathcal{A} \\rtimes_r G$ arising from action
s of discrete groups. Applications to determining the simplicity of reduce
d crossed products are provided.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesca Arici (Leiden University)
DTSTART;VALUE=DATE-TIME:20201209T200000Z
DTEND;VALUE=DATE-TIME:20201209T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/37
DESCRIPTION:Title: SU(2)-symmetries\, exact sequences of C*-algebras and subproduct systems<
/a>\nby Francesca Arici (Leiden University) as part of NYC noncommutative
geometry seminar\n\n\nAbstract\nMotivated by the study of symmetries of C*
-algebras as well as by multivariate operator theory\, in this talk we wil
l introduce the notion of an SU(2)-equivariant subproduct system of Hilber
ts spaces. Through an explicit construction in operator theory\, we will o
btain Toeplitz and Cuntz-Pimsner algebras\, and provide results about the
ir topological invariants. \n\nIn particular\, we will show that the Toepl
itz algebra of the subproduct system of an irreducible SU(2) representatio
n is equivariantly KK-equivalent to the algebra of complex numbers\, so th
at the (K)K-theory groups of the Cuntz-Pimsner algebra can be effectively
computed using an exact sequence involving an analogue of the Euler class.
\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marat Markin (California State University\, Fresno)
DTSTART;VALUE=DATE-TIME:20201216T200000Z
DTEND;VALUE=DATE-TIME:20201216T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/38
DESCRIPTION:Title: On the Smoothness of Weak Solutions of an Abstract Evolution Equation wit
h a Scalar Type Spectral Operator\nby Marat Markin (California State U
niversity\, Fresno) as part of NYC noncommutative geometry seminar\n\n\nAb
stract\nGiven the abstract evolution equation\n\n$$y\\prime (t) = Ay(t)\,
\\quad t ≥ 0\, \\hskip2cm (AEE)$$\n\nwith a scalar type spectral operato
r $A$ in a complex Banach space\, we find conditions on $A$\, formulated e
xclusively in terms of the location of its spectrum in the complex plane\,
necessary and sufficient for all weak solutions of the equation\, which a
priori need not be strongly differentiable\, to be strongly infinite diff
erentiable or strongly Gevrey ultradifferentiable of order $\\beta\\ge 1$\
, \nin particular analytic or entire\, on $[0\,\\infty)$ or \n$(0\, \\inft
y)$. We also reveal certain inherent smoothness improvement effects and sh
ow that\, if all weak solutions of the equation are Gevrey ultradifferenti
able of orders less than one\, then the operator is necessarily bounded.\n
\nIn addition\, we find characterizations of the generation of strongly in
finite differentiable and Gevrey ultradifferentiable $C_0$-semigroups by s
calar type spectral operators.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sylvie Paycha (Universität Potsdam)
DTSTART;VALUE=DATE-TIME:20210210T200000Z
DTEND;VALUE=DATE-TIME:20210210T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/39
DESCRIPTION:Title: Regularised traces and Getzler’s rescaling revisited\nby Sylvie Pay
cha (Universität Potsdam) as part of NYC noncommutative geometry seminar\
n\n\nAbstract\nInspired by Gilkey's invariance theory\, Connes' deformati
on to the\nnormal cone and Getzler's rescaling method\, we single out a cl
ass of\ngeometric operators among pseudodifferential operators acting on\n
sections of a class of natural vector bundles\, to which we attach a \nres
caling degree.\nThis degree is then used to express regularised traces of
geometric\noperators in terms of a rescaled limit of Wodzicki residues.
When\napplied to complex powers of the square of a Dirac operator\, this
\namounts to expressing the index of a Dirac operator in terms of a local\
nresidue involving the Getzler rescaled limit of its square.\n\nThis is
joint work with Georges Habib.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clément Dell'Aiera (ENS Lyon)
DTSTART;VALUE=DATE-TIME:20210217T200000Z
DTEND;VALUE=DATE-TIME:20210217T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/40
DESCRIPTION:Title: Dynamic asymptotic dimension and homology\nby Clément Dell'Aiera (EN
S Lyon) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nGrou
poid homology has attracted increasing attention from from the topological
dynamics and operator algebras communities following the work of Matui. M
atui's HK conjecture predicts that the K-theory groups of the reduced C*-a
lgebra of a minimal essentially principal ample groupoid coincides with it
s homology groups. We prove that homology of principal ample groupoids van
ish in degree above its dynamical asymptotic dimension\, a notion of dimen
sion from topological dynamics. We deduce several consequences: Matui's HK
conjecture holds for low dimensional principal ample groupoids\, and clas
sification of their reduced C*-algebra. (Joint work with Christian Bonicke
\, Jamie Gabe and Rufus Willett)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aristides Katavolos (University of Athens)
DTSTART;VALUE=DATE-TIME:20210224T200000Z
DTEND;VALUE=DATE-TIME:20210224T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/41
DESCRIPTION:Title: Harmonic functions\, crossed products and approximation properties\nb
y Aristides Katavolos (University of Athens) as part of NYC noncommutative
geometry seminar\n\n\nAbstract\nThe space of harmonic functions on a loca
lly compact group $G$ is the fixed point space of a\ncertain Markov operat
or. Its `quantization'\, the corresponding fixed point space of operators
on $L^2(G)$\, coincides with the weak-* closed bimodule over the group von
Neumann algebra generated by this space. We examine the analogous spaces
of jointly harmonic functions\nand their quantized operator bimodules. Thi
s leads to two different notions of crossed product of operator spaces by
actions of $G$\, which coincide when $G$ satisfies a certain approximation
property. The corresponding (dual) notions of crossed products of (co-) a
ctions by the von Neumann algebra of $G$ always coincide. This gives a new
approach to the correspondence between spectral synthesis and operator sy
nthesis.\n\n\nThe talk is a survey of joint work with M. Anoussis and I.G.
Todorov\, and of recent work by D. Andreou.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Gonçalves (Universidade Federal de Santa Catarina)
DTSTART;VALUE=DATE-TIME:20210303T200000Z
DTEND;VALUE=DATE-TIME:20210303T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/42
DESCRIPTION:Title: A generalization of shifts of finite type motivated by C*-algebra theory<
/a>\nby Daniel Gonçalves (Universidade Federal de Santa Catarina) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nUltragraphs algebra
s generalized Exel-Laca and graph algebras. In this talk we describe ultra
graphs\, their associated edge shift spaces (which generalize SFT for infi
nite alphabets)\, and their associated C*-algebras and groupoids. At the e
nd\, we present results regarding continuous orbit equivalence and full gr
oups associated to ultragraphs\, and describe how to apply these results t
o graph and Exel-Laca algebras.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joakim Arnlind (Linköping University)
DTSTART;VALUE=DATE-TIME:20210310T200000Z
DTEND;VALUE=DATE-TIME:20210310T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/43
DESCRIPTION:Title: Curvature for a class of noncommutative minimal surfaces\nby Joakim A
rnlind (Linköping University) as part of NYC noncommutative geometry semi
nar\n\n\nAbstract\nThe theory of minimal surfaces is an old and still quit
e active field\nof research\, and it is natural to ask if there exists a c
orresponding\ntheory in noncommutative geometry? In particular\, analogues
of minimal\nsubmanifolds appear in physical theories related to quantum g
ravity\n(string/membrane theory). I will present an approach to noncommuta
tive\nminimal surfaces taking an equational point of view (rather than a\n
variational one). After providing some background material leading to\nour
definition of noncommutative minimal surfaces\, I will discuss a\nframewo
rk for constructing Levi-Civita connections and curvature of\nsuch surface
s. These considerations naturally lead to a general\ndiscussion of metric
connections on hermitian modules.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cédric Arhancet (Lycée Lapérouse)
DTSTART;VALUE=DATE-TIME:20210317T190000Z
DTEND;VALUE=DATE-TIME:20210317T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/44
DESCRIPTION:Title: Entangling quantum information theory and Fourier multipliers on operator
algebras\nby Cédric Arhancet (Lycée Lapérouse) as part of NYC nonc
ommutative geometry seminar\n\n\nAbstract\nOne of the most fundamental que
stions in quantum information concerns with the amount of information that
can be transmitted reliably through a quantum channel. For that\, many ca
pacities and entropies was introduced for describing the capability of the
channel for delivering information from the sender to the receiver. In th
is talk\, we will explain how to obtain the exact values of some of these
quantities for large classes of channels by using the theory of Fourier mu
ltipliers on quantum groups.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yulia Kuznetsova (Université de Franche-Comté)
DTSTART;VALUE=DATE-TIME:20210324T190000Z
DTEND;VALUE=DATE-TIME:20210324T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/45
DESCRIPTION:Title: Quantum semigroups\, what is known or not\nby Yulia Kuznetsova (Unive
rsité de Franche-Comté) as part of NYC noncommutative geometry seminar\n
\n\nAbstract\nWhereas it is straightforward to define a topological group\
, one\nneeds more caution when dealing with semigroups: their multiplicati
on might\nbe only separately and not jointly continuous. This happens in t
he case as\nnatural as the weakly almost periodic of a locally compact gro
up. The\ndistinction exists also in the quantum case\, first addressed by
Mattthew\nDaws. After discussing it\, I will speak on duality and known li
nks with\nquantum compactifications. Finally\, I will pass to some results
on the\nstructure of quantum semigroups. The last part is work in progres
s with\nBiswarup Das.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Igor Fulman (Arizona State University)
DTSTART;VALUE=DATE-TIME:20210428T190000Z
DTEND;VALUE=DATE-TIME:20210428T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/47
DESCRIPTION:Title: Introduction to von Neumann Algebras\, I\nby Igor Fulman (Arizona Sta
te University) as part of NYC noncommutative geometry seminar\n\n\nAbstrac
t\nBasic examples. Strong\, weak and operator norm topology. Bicommutant t
heorem.\nProjections.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Igor Fulman (Arizona State University)
DTSTART;VALUE=DATE-TIME:20210505T190000Z
DTEND;VALUE=DATE-TIME:20210505T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/48
DESCRIPTION:Title: Introduction to von Neumann Algebras\, II\nby Igor Fulman (Arizona St
ate University) as part of NYC noncommutative geometry seminar\n\n\nAbstra
ct\nFactors. Direct sum of factors. Finite and infinite projections. Purel
y infinite projections. Factors of type I\, II and III. Examples.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Igor Fulman (Arizona State University)
DTSTART;VALUE=DATE-TIME:20210512T190000Z
DTEND;VALUE=DATE-TIME:20210512T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/49
DESCRIPTION:Title: Introduction to von Neumann Algebras\, III\nby Igor Fulman (Arizona S
tate University) as part of NYC noncommutative geometry seminar\n\n\nAbstr
act\nExamples of factors of type I\, II and III . Group von Neumann algebr
as. Crossed products.\nIntroduction to Tomita-Takesaki theory.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vasilisa Shramchenko (Université de Sherbrooke)
DTSTART;VALUE=DATE-TIME:20210421T190000Z
DTEND;VALUE=DATE-TIME:20210421T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/50
DESCRIPTION:Title: Poncelet theorem and Painlevé VI\nby Vasilisa Shramchenko (Universit
é de Sherbrooke) as part of NYC noncommutative geometry seminar\n\n\nAbst
ract\nIn 1995 Hitchin constructed explicit algebraic solutions to the Pain
levé VI (1/8\,-1/8\,1/8\,3/8) equation starting with any Poncelet trajec
tory\, that is a closed billiard trajectory inscribed in a conic and circu
mscribed about another conic. In this talk I will show that Hitchin's cons
truction is nothing but the Okamoto transformation between Picard's soluti
on and the general solution of the Painlevé VI (1/8\,-1/8\,1/8\,3/8) equa
tion. Moreover\, this Okamoto transformation can be written in terms of an
Abelian differential of the third kind on the associated elliptic curve.\
n
LOCATION:https://researchseminars.org/talk/NYC-NCG/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Igor Nikolaev (St. John's University)
DTSTART;VALUE=DATE-TIME:20210331T190000Z
DTEND;VALUE=DATE-TIME:20210331T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/51
DESCRIPTION:Title: Quantum dynamics of elliptic curves\nby Igor Nikolaev (St. John's Uni
versity) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nWe
calculate the $K$-theory of a crossed product $C^*$-algebra \n $\\maths
cr{A}_{RM}\\rtimes\\mathscr{E}(K)$\, where $\\mathscr{A}_{RM}$ is the \n
noncommutative torus with real multiplication and $\\mathscr{E}(K)$ is
an elliptic curve \n over the number field $K$. We use this result to e
valuate the rank and \n the Shafarevich-Tate group of $\\mathscr{E}(K)$.
\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Angel Roman (William & Mary)
DTSTART;VALUE=DATE-TIME:20210407T190000Z
DTEND;VALUE=DATE-TIME:20210407T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/52
DESCRIPTION:Title: The Mackey bijection for reductive groups and continuous fields of reduce
d group C*-algebras\nby Angel Roman (William & Mary) as part of NYC no
ncommutative geometry seminar\n\n\nAbstract\nIn the 1970's\, George Mackey
proposed that there should be some kind of analogy between unitary repres
entations of semisimple groups $G$ and unitary representations of its Car
tan motion group $G_0=K\\ltimes \\mathfrak{g}/\\mathfrak{k}$\, where $K$ i
s a maximal compact subgroup of $G$. Eventually a precise bijection was co
nstructed between the irreducible tempered unitary representations of $G$
and the irreducible unitary representations of $G_0$. In a joint work with
Nigel Higson we characterized the Mackey bijection using continuous field
s of reduced group $C^*$-algebra of complex reductive group. We constructe
d an embedding between the reduced $C^*$-algebras of $G_0$ and $G$. Time p
ermitting\, I will discuss ongoing work (with Nigel Higson and Pierre Clar
e) toward a generalization to a wider class of groups.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Frei (University of Copenhagen)
DTSTART;VALUE=DATE-TIME:20210414T190000Z
DTEND;VALUE=DATE-TIME:20210414T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/53
DESCRIPTION:Title: Relative Cuntz-Pimsner algebras: Gauge-invariant uniqueness theorem and t
he lattice of gauge-invariant ideals\nby Alexander Frei (University of
Copenhagen) as part of NYC noncommutative geometry seminar\n\n\nAbstract\
nWe start with an abstract definition of C*-correspondences comparing them
to Fell bundles.\nAfter a first few basic results\, we then swiftly move
on to their representations.\nWe introduce here the concept of covariances
and relative Cuntz-Pimsner algebras.\n\nFrom here we go into a detailed a
nalysis of covariances within the category of C*-correpondences.\nWe obtai
n here a systematic reduction leading us to a parametrisation of relative
Cuntz-Pimsner algebras.\n\nWith this at hand we arrive at the gauge-invari
ant uniqueness theorem\, for all (arbitrary) gauge-equivariant representat
ions at once.\n\nFrom here we move on to the analysis part of the program.
\nWe study the covariances in the case of the Fock representation and its
quotients.\nAs a result we derive that the parametrisation of relative Cun
tz-Pimsner algebras is classifying.\nIn other words\, we obtain a complete
and intrinsic picture of the lattice of quotients\, and equivalently of g
auge-invariant ideals.\n\nIf time permits\, we finish off with the next ch
apter on their induced Fell bundles\, as already investigated by Schweizer
.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Katz (St. John's University)
DTSTART;VALUE=DATE-TIME:20210602T190000Z
DTEND;VALUE=DATE-TIME:20210602T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/54
DESCRIPTION:Title: On real Sigma*-algebras\nby Alexander Katz (St. John's University) as
part of NYC noncommutative geometry seminar\n\n\nAbstract\nReal analogues
of (complex) Sigma*-algebras are introduced and their basic properties an
d connections with real von Neumann algebras are discussed.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandre Afgoustidis (CNRS\, l’Institut Élie Cartan de Lorrain
e)
DTSTART;VALUE=DATE-TIME:20210519T150000Z
DTEND;VALUE=DATE-TIME:20210519T160000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/55
DESCRIPTION:Title: The tempered dual of real or p-adic reductive groups\, and its noncommuta
tive geometry (joint work with Anne-Marie Aubert)\nby Alexandre Afgous
tidis (CNRS\, l’Institut Élie Cartan de Lorraine) as part of NYC noncom
mutative geometry seminar\n\n\nAbstract\nSuppose G is a real or p-adic red
uctive group. The space of irreducible tempered representations of G comes
equipped with the Fell topology\, which encodes important phenomena in re
presentation theory. The topology is usefully studied by noncommutative-g
eometric methods: the tempered dual naturally identifies with the spectrum
of the C*-algebra of G\, and its connected components identify with the s
pectra of certain `blocks’ in the C*-algebra. \n\nFor real reductive gro
ups\, A. Wassermann proved in 1987 that each `block’ has\, up to Morita
equivalence\, a beautiful and simple structure. This was a crucial step in
his proof of the Baum-Connes-Kasparov conjecture for G. For p-adic groups
\, it is not obvious at all that such a structure can exist\, but importan
t examples were given by R. Plymen and his students. \n\nIn my talk\, I wi
ll report on joint work with Anne-Marie Aubert which (1) for arbitrary G\,
gives a geometric condition for the existence of a Wassermann-type struct
ure on a given block\, and (2) when G is a quasi-split symplectic\, orthog
onal or unitary group\, explicitly determines the connected components of
the tempered dual for which the geometric assumption is satisfied.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christian Bonicke (University of Glasgow)
DTSTART;VALUE=DATE-TIME:20210526T190000Z
DTEND;VALUE=DATE-TIME:20210526T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/56
DESCRIPTION:Title: Regularity properties for ample groupoids and the type semigroup\nby
Christian Bonicke (University of Glasgow) as part of NYC noncommutative ge
ometry seminar\n\n\nAbstract\nI will introduce the type semigroup of an am
ple groupoid and explain how it encodes dynamical properties of the groupo
id in an algebraic framework. In particular I will explain how the fine st
ructure of the type semigroup relates to certain regularity properties of
the groupoid\, which play a prominent role in recent attempts to develop a
dynamical analogue of the Toms-Winter conjecture for simple separable nuc
lear C*-algebras.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesc Perera (Universitat Autònoma de Barcelona)
DTSTART;VALUE=DATE-TIME:20210609T190000Z
DTEND;VALUE=DATE-TIME:20210609T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/57
DESCRIPTION:Title: Traces on ultrapower C*-algebras\nby Francesc Perera (Universitat Aut
ònoma de Barcelona) as part of NYC noncommutative geometry seminar\n\n\nA
bstract\nEvery sequence of traces on a C*-algebra induces a limit trace on
a free ultrapower. I will discuss the natural question of characterizing
when this set of limit traces is dense\, and mention the use of techniques
coming from the theory of Cuntz semigroups to obtain such a characterizat
ion. This talk is based on joint work with Ramon Antoine\, Leonel Robert\,
and Hannes Thiel.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shanna Dobson (California State University\, Los Angeles)
DTSTART;VALUE=DATE-TIME:20210623T190000Z
DTEND;VALUE=DATE-TIME:20210623T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/58
DESCRIPTION:Title: Pro-Diamond and the Geometrization of Local Langlands\nby Shanna Dobs
on (California State University\, Los Angeles) as part of NYC noncommutati
ve geometry seminar\n\n\nAbstract\nWe recently conjectured a pro-diamond i
n our Efimov K-theory of Diamonds\, for diamonds in the sense of Scholze.
In this talk\, we discuss our pro-diamond formalism and survey the many in
carnations of diamonds in the geometrization of the local Langlands Corres
pondence.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/58/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anne-Marie Aubert (CNRS\, Sorbonne Université - Université de Pa
ris)
DTSTART;VALUE=DATE-TIME:20210630T190000Z
DTEND;VALUE=DATE-TIME:20210630T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/59
DESCRIPTION:Title: Stratified equivalences and Bernstein Center\nby Anne-Marie Aubert (C
NRS\, Sorbonne Université - Université de Paris) as part of NYC noncommu
tative geometry seminar\n\n\nAbstract\nIn the first part of the talk\, we
will introduce the notion of stratified equivalence for finite type k-alge
bras\, which is a weakening of Morita equivalence\, and illustrate it with
examples.\n\nNext\, we will recall the Bernstein decomposition of the cat
egory of smooth representations of a p-adic reductive group and show how s
tratified equivalence occurs in this context\, notably in the case of inne
r forms of the special linear group.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fabio Cipriani (Politecnico di Milano)
DTSTART;VALUE=DATE-TIME:20210714T190000Z
DTEND;VALUE=DATE-TIME:20210714T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/60
DESCRIPTION:Title: On a noncommutative Sierpiński gasket\nby Fabio Cipriani (Politecnic
o di Milano) as part of NYC noncommutative geometry seminar\n\n\nAbstract\
nWe illustrate the construction of a C*-algebra A that can be genuinely in
terpreted as a quantization of the classical Sierpiński gasket\, the most
studied instance of a self-similar fractal space. We further describe the
discrete and continuous spectrum of A\, the structure of the traces on A
as well as the construction of a Dirichlet form E and of a spectral triple
(A\,D\,H).\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pieter Spaas (UCLA)
DTSTART;VALUE=DATE-TIME:20210707T190000Z
DTEND;VALUE=DATE-TIME:20210707T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/61
DESCRIPTION:Title: Cohomological obstructions to lifting properties for full C*-algebras of
property (T) groups\nby Pieter Spaas (UCLA) as part of NYC noncommutat
ive geometry seminar\n\n\nAbstract\nWe will introduce and discuss the lift
ing property (LP) and local lifting property (LLP) for full group C*-algeb
ras. We will then introduce a new method to refute these properties\, base
d on non-vanishing of second cohomology groups. This will allow us to deri
ve that many natural examples of (relative) property (T) groups fail the L
LP\, and further large classes fail the LP. This is based on joint work wi
th Adrian Ioana and Matthew Wiersma.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/61/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mitch Haslehurst (University of Victoria)
DTSTART;VALUE=DATE-TIME:20210616T190000Z
DTEND;VALUE=DATE-TIME:20210616T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/62
DESCRIPTION:Title: Relative K-theory with applications to factor groupoids\nby Mitch Has
lehurst (University of Victoria) as part of NYC noncommutative geometry se
minar\n\n\nAbstract\nIn this talk I will speak about a portrait of relativ
e K-theory for C*-algebras inspired by a setup due to Max Karoubi using Ba
nach categories. After presenting some useful exact sequences\, I will sho
w how the portrait gives the same data\, although through a different lens
\, as the K-groups that arise from the mapping cone construction. After th
is\, I will \npresent some examples of C*-algebras from factor groupoids w
hose K-theory data are computable (in fact\, controllable\, to a certain d
egree) using these relative K-theory tools.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/62/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jens Kaad (University of Southern Denmark)
DTSTART;VALUE=DATE-TIME:20210818T190000Z
DTEND;VALUE=DATE-TIME:20210818T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/63
DESCRIPTION:Title: Exterior products of compact quantum metric spaces\nby Jens Kaad (Uni
versity of Southern Denmark) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nThe theory of compact quantum metric spaces was initiated
by Rieffel in the late nineties. Important inspiration came from the fund
amental observation of Connes saying that the metric on a compact spin man
ifold can be recovered from the Dirac operator. A compact quantum metric s
pace is an operator system (e.g. a unital C*-algebra) equipped with a semi
norm which metrizes the weak-*-topology on the state space via the associa
ted Monge-Kantorovich metric. In this talk we study tensor products of com
pact quantum metric spaces with specific focus on seminorms arising from t
he exterior product of spectral triples. On our way we obtain a novel char
acterization of compact quantum metric spaces using finite dimensional app
roximations and we apply this characterization to propose a completely bou
nded version of the theory.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/63/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scott Schmieding (University of Denver)
DTSTART;VALUE=DATE-TIME:20210721T190000Z
DTEND;VALUE=DATE-TIME:20210721T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/64
DESCRIPTION:Title: Flow equivalence and mapping class groups for symbolic dynamical systems<
/a>\nby Scott Schmieding (University of Denver) as part of NYC noncommutat
ive geometry seminar\n\n\nAbstract\nThere have been many fruitful connecti
ons between symbolic dynamical systems and operator algebras. We'll first
give a very brief survey of some examples of this\, before focusing on the
notion of flow equivalence and mapping class groups in the context of sym
bolic dynamics. The talk will be designed so that little to no knowledge o
f dynamical systems is necessary.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/64/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bernhard Burgstaller (Universidade Federal de Santa Catarina)
DTSTART;VALUE=DATE-TIME:20210728T190000Z
DTEND;VALUE=DATE-TIME:20210728T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/65
DESCRIPTION:Title: A kind of KK-theory of rings\nby Bernhard Burgstaller (Universidade F
ederal de Santa Catarina) as part of NYC noncommutative geometry seminar\n
\n\nAbstract\nA group equivariant $KK$-theory\nfor rings will be defined a
nd studied\nin analogy to Kasparov's $KK$-theory for\n$C^*$-algebras.\nIt
is a kind of linearization of the category\nof rings by allowing addition
of homomorphisms\, imposing also homotopy invariance\, invertibility of ma
trix corner embeddings\,\nand allowing morphisms which are the opposite sp
lit of split exact sequences.\nWe demonstrate the potential of this theory
\nby proving for example equivalence induced by Morita equivalence\nand a
Green-Julg isomorphism in this framework.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/65/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laurent Cantier (Universitat Autònoma de Barcelona)
DTSTART;VALUE=DATE-TIME:20210908T190000Z
DTEND;VALUE=DATE-TIME:20210908T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/66
DESCRIPTION:Title: Classification of unitary elements of a C*-algebra\nby Laurent Cantie
r (Universitat Autònoma de Barcelona) as part of NYC noncommutative geome
try seminar\n\n\nAbstract\nThe Cuntz semigroup has emerged as an essential
tool for the classification of (non-simple) C*-algebras. For instance\, i
t has been shown that the functor Cu classifies positive elements of any C
*-algebra of stable rank 1 (up to approximately unitarily equivalence). An
immediate corollary is that the Cuntz semigroup is a complete invariant f
or AI algebras. In this talk\, I will raise the question of classification
of unitary elements of a C*-algebra (of stable rank 1). It is unlikely th
at the Cuntz semigroup alone is sufficient to classify these elements and
one can speculate that an ingredient with $K_1$ flavor has to be added. Ne
vertheless\, I will prove that this remains true when restricting to AF al
gebras and I will discuss how one could to extend this classification resu
lt to a larger class of C*-algebra.\n\nEven though I will recall definitio
ns of the Cuntz semigroup and classifying functor\, it might good to point
out that knowledge about C*-algebras are needed.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/66/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lyudmila Turowska (Chalmers University of Technology)
DTSTART;VALUE=DATE-TIME:20210901T190000Z
DTEND;VALUE=DATE-TIME:20210901T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/67
DESCRIPTION:Title: Multipliers and Approximation Properties\nby Lyudmila Turowska (Chalm
ers University of Technology) as part of NYC noncommutative geometry semin
ar\n\n\nAbstract\nOne can encode various properties of locally compact gro
ups from properties of Banach algebras associated to the groups and vice v
ersa. In this talk I will explain how Herz-Schur multipliers have been use
d to study some of those properties. Then I will talk about generalization
of such multipliers to the setting of dynamical systems and explain how t
he technique of Herz-Schur multipliers can be extended to study approximat
ion properties of crossed product C*-algebras. I shall also discuss compac
t and completely compact multipliers.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/67/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefan Wagner (Blekinge Institute of Technology)
DTSTART;VALUE=DATE-TIME:20210825T190000Z
DTEND;VALUE=DATE-TIME:20210825T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/68
DESCRIPTION:Title: Factor systems as a computational framework for noncommutative principal
bundles - with an application to Atiyah’s famous Lie algebra sequence\nby Stefan Wagner (Blekinge Institute of Technology) as part of NYC nonc
ommutative geometry seminar\n\n\nAbstract\nFree C*-dynamical systems\, in
the sense of Ellwood\, provide a natural framework for noncommutative prin
cipal bundles\, which are becoming increasingly prevalent in various appli
cations to noncommutative geometry and mathematical physics. \nOne of the
key features of free C*-dynamical systems are their associated factor syst
ems\, which make them accessible to classification\, K-theoretic considera
tions\, and computations in general. \nIn this talk we present the recent
theory of factor systems for free C*-dynamical systems and apply it to giv
e a derivation-based Atiyah sequence for noncommutative principal bundles.
\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/68/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Brix (University of Glasgow)
DTSTART;VALUE=DATE-TIME:20210915T190000Z
DTEND;VALUE=DATE-TIME:20210915T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/69
DESCRIPTION:Title: Flow equivalence and C*-algebras\nby Kevin Brix (University of Glasgo
w) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nTopologic
al dynamical systems are an abundant source of examples of interesting C*-
algebras\, e.g. Cuntz-Krieger algebras\, graph C*-algebras and their highe
r rank and twisted variations. Dynamical relations such as conjugacy or fl
ow equivalence are an invitation to study the fine structure of these C*-a
lgebras and isomorphisms between them. I intend to discuss some central re
sults as well as important open questions in this field.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/69/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Timothy Schenkel (Ohio University)
DTSTART;VALUE=DATE-TIME:20210811T190000Z
DTEND;VALUE=DATE-TIME:20210811T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/70
DESCRIPTION:Title: Regular Ideals of Locally-Convex Kumjian-Pask Algebras\nby Timothy Sc
henkel (Ohio University) as part of NYC noncommutative geometry seminar\n\
n\nAbstract\nWe give a vertex set description for basic\, graded\, regular
ideals of locally-convex Kumjian-Pask Algebras. We also show that Conditi
on (B) is preserved when taking the quotient by a basic\, graded\, regular
ideal. We further show that when a locally-convex\, row-finite k-graph sa
tisfies Condition (B)\, all regular ideals are graded.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/70/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Diego Martínez (University of Madrid)
DTSTART;VALUE=DATE-TIME:20211006T190000Z
DTEND;VALUE=DATE-TIME:20211006T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/71
DESCRIPTION:Title: C* and geometric properties of inverse semigroups\nby Diego Martínez
(University of Madrid) as part of NYC noncommutative geometry seminar\n\n
\nAbstract\nInverse semigroups are a generalization of groups\, where elem
ents in an inverse semigroup can be thought of as partial symmetries of a
space (instead of global symmetries\, as in the group case). Out of these
one can construct a uniform Roe algebra algebra just as in the group case\
, and study its properties. In this talk\, we shall characterize when such
C*-algebra is nuclear by means of an intrinsic metric in the semigroup\,
and prove that its nuclearity is equivalent to the semigroup having prope
rty A. Moreover\, one can also study amenability notions in this case\, an
d relate the trace space of the uniform Roe algebra with certain invariant
measures in the semigroup. This talk is based on joint work with Pere Ara
and Fernando Lledó.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/71/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Plazas (Pontificia Universidad Javeriana)
DTSTART;VALUE=DATE-TIME:20210922T190000Z
DTEND;VALUE=DATE-TIME:20210922T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/72
DESCRIPTION:Title: Noncommutative geometry of arithmetic groups\nby Jorge Plazas (Pontif
icia Universidad Javeriana) as part of NYC noncommutative geometry seminar
\n\n\nAbstract\nIn this talk we look at constructions from noncommutative
geometry which encode various number theoretic properties of arithmetic gr
oups.\n\nIn the first part of the talk we will discuss the relation betwee
n Conway's big picture and the Connes-Marcolli Gl(2) system. This relation
leads to noncommutative spaces encoding properties of groups commensurab
le with the modular group. In the second part of the talk we discuss Hecke
operators for Bianchi groups and the action of these in K-homology via Br
edon homology and the Baum-Connes conjecture.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/72/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tyrone Crisp (University of Maine)
DTSTART;VALUE=DATE-TIME:20210929T190000Z
DTEND;VALUE=DATE-TIME:20210929T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/73
DESCRIPTION:Title: Frobenius C*-algebras and local adjunctions of C*-correspondences\nby
Tyrone Crisp (University of Maine) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nMany interesting and important C*-algebras do not
have multiplicative identities\, and C*-algebraists have long known how to
deal with this fact by using approximate identities\, multiplier algebras
\, etc. A similar situation arises when one attempts to use methods of cat
egory theory to study modules over C*-algebras: objects like "the category
of compact operators on Hilbert spaces" don't fit neatly into the standar
d theory of categories\, because they lack identity morphisms\; but they d
o fit nicely into a theory of non-unital C*-categories and their multiplie
r categories\, as developed by Kandelaki\, Mitchener\, Vasselli\, Antoun-V
oigt\, and others. This talk concerns an adaptation of the important categ
orical notion of adjoint functors to this non-unital-category point of vie
w. I will present a definition (taken from joint work with Pierre Clare an
d Nigel Higson) of adjoint functors between categories of compact operator
s on Hilbert C*-modules\, and I will explain how this definition correspon
ds to a natural notion of Frobenius C*-algebra\, mirroring a correspondenc
e between two-sided adjunctions and Frobenius algebras in classical catego
ry theory.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/73/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gilles Castro (Universidade Federal de Santa Catarina)
DTSTART;VALUE=DATE-TIME:20211103T190000Z
DTEND;VALUE=DATE-TIME:20211103T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/74
DESCRIPTION:Title: KMS states for generalized gauge actions on C*-algebras associated with s
elf-similar sets\nby Gilles Castro (Universidade Federal de Santa Cata
rina) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nOn the
one hand\, equilibrium states in quantum statistical mechanics can be des
cribed using the KMS condition. On the other hand\, in classical statistic
al mechanics\, one way of finding equilibrium states is via an operator ca
lled the Ruelle operator. It turns out that for some noncommutative C*-alg
ebras built from classical objects\, there are some relationships between
KMS states on the C*-algebras and properties of the Ruelle operator. In th
is talk\, after recalling the needed definitions\, I will present some res
ults in this direction for C*-algebras associated with self-similar sets.\
n
LOCATION:https://researchseminars.org/talk/NYC-NCG/74/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Becky Armstrong (Universität Münster)
DTSTART;VALUE=DATE-TIME:20211013T190000Z
DTEND;VALUE=DATE-TIME:20211013T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/75
DESCRIPTION:Title: A uniqueness theorem for twisted groupoid C*-algebras\nby Becky Armst
rong (Universität Münster) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nTwisted groupoid C*-algebras were introduced by Renault i
n 1980 and are a generalisation of twisted group C*-algebras\, which are t
he C*-algebraic analogue of twisted group rings. Through the work of Renau
lt and more recently of Li\, it has emerged that every simple classifiable
C*-algebra can be realised as a twisted groupoid C*-algebra\, a result th
at has led to increased interest in the structure of these C*-algebras. In
this talk I will describe the construction of reduced twisted C*-algebras
of Hausdorff étale groupoids. I will then discuss my recent preprint in
which I prove a uniqueness theorem for these algebras and use this to char
acterise simplicity in the case where the groupoid is effective.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/75/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vadim Alekseev (Technische Universität Dresden)
DTSTART;VALUE=DATE-TIME:20211110T200000Z
DTEND;VALUE=DATE-TIME:20211110T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/76
DESCRIPTION:Title: Geometry of sofic approximations\nby Vadim Alekseev (Technische Unive
rsität Dresden) as part of NYC noncommutative geometry seminar\n\n\nAbstr
act\nIn the recent years\, there has been substantial activity\nconnecting
graph theory and group theory via the concept of a metric\napproximation
of an infinite group by finite objects (groups or\ngraphs)\, particularly
around sofic groups. This lead to numerous\nresults which describe approxi
mation properties of the group (for\ninstance\, amenability or Haagerup pr
operty) in terms of geometric\nproperties of its approximations (e.g. hype
rfiniteness or coarse\nembeddability in a Hilbert space of a graph sequenc
e). In this talk\, I\nwill describe these connections between the two worl
ds (groups and\ngraphs) and some recent results around them.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/76/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicolas Monod (École Polytechnique Fédérale de Lausanne)
DTSTART;VALUE=DATE-TIME:20211020T190000Z
DTEND;VALUE=DATE-TIME:20211020T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/77
DESCRIPTION:Title: Type I\, Gelfand pairs and Iwasawa decompositions\nby Nicolas Monod (
École Polytechnique Fédérale de Lausanne) as part of NYC noncommutative
geometry seminar\n\n\nAbstract\nIn this talk\, we will prove that every G
elfand pair admits an Iwasawa\ndecomposition.\n\nBefore that\, we will exp
lain what Gelfand pairs are and why Iwasawa\ndecompositions are useful.\n\
nAt the end\, we will discuss a conjecture studied in collaboration with\n
M. Kalantar and P.-E. Caprace\, speculating about similar results for\ntyp
e I groups.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/77/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrey Glubokov (Purdue University)
DTSTART;VALUE=DATE-TIME:20211027T190000Z
DTEND;VALUE=DATE-TIME:20211027T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/78
DESCRIPTION:Title: Cluster algebra and Jones polynomials\nby Andrey Glubokov (Purdue Uni
versity) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nClu
ster $C^*$-algebra of the sphere with two cusps and its K-theory is being
investigated to demonstrate a connection to the Jones polynomials.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/78/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aaron Tikuisis (University of Ottawa)
DTSTART;VALUE=DATE-TIME:20211117T200000Z
DTEND;VALUE=DATE-TIME:20211117T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/79
DESCRIPTION:Title: Nuclear dimension and Z-stability of simple C*-algebras\nby Aaron Tik
uisis (University of Ottawa) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nMuch recent work in C*-algebra theory has focused on regu
larity properties. This is a response to examples of "irregular" simple nu
clear C*-algebras by Villadsen (algebras with perforation in their ordered
K-theory)\, Rordam (algebras with both finite and infinite projections)\,
and Toms (algebras that cannot be distinguished by ordered K-theory and t
races). I will describe two regularity properties: finite nuclear dimensio
n and Z-stability (aka Jiang-Su-stability). In joint work with Castillejos
\, Evington\, White\, and Winter\, we showed that these properties coincid
e for simple separable nuclear unital C*-algebras\, verifying a conjecture
of Toms and Winter. I will discuss this result and its implications.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/79/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xin Ma (University of Memphis)
DTSTART;VALUE=DATE-TIME:20211124T200000Z
DTEND;VALUE=DATE-TIME:20211124T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/80
DESCRIPTION:Title: Fiberwise amenability and almost elementariness for étale groupoids\
nby Xin Ma (University of Memphis) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nIn this talk\, I will discuss two new properties fo
r locally compact Hausdorff étale groupoids. One is from a coarse geometr
ic view called fiberwise amenability. Another one is called almost element
ariness\, which is a new finite-dimensional approximation property. I will
explain how these notions related to almost finiteness defined by Matui a
nd refined by Kerr and show our almost elementariness implying tracial Z-s
tability of reduced groupoid C*-algebras. As an application. This implies
that Matui's almost finiteness in the groupoid setting also implies Z-stab
ility when the groupoid is minimal 2nd countable and topological amenable.
This was open in general before. I will also present more applications if
time permits. This is based on joint work with Jianchao Wu.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/80/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yifeng Huang (University of Michigan)
DTSTART;VALUE=DATE-TIME:20211201T200000Z
DTEND;VALUE=DATE-TIME:20211201T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/81
DESCRIPTION:Title: Point count of the variety of modules over the quantum plane over a finit
e field\nby Yifeng Huang (University of Michigan) as part of NYC nonco
mmutative geometry seminar\n\n\nAbstract\nIn 1960\, Feit and Fine gave a f
ormula for the number of pairs of commuting n by n matrices over a finite
field. We consider a quantum deformation of the problem\, namely\, countin
g pairs (A\,B) of n by n matrices over a finite field that satisfy AB=qBA
for a fixed nonzero scalar q. We give a formula for this count in terms of
the order of q as a root of unity\, generalizing Feit and Fine's result.
In this talk\, after explaining the title and the results\, we will discus
s a curious phenomenon that one sees when comparing the commutative case (
q=1) and the general case from a geometric viewpoint.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/81/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Réamonn Ó Buachalla (Charles University\, Prague)
DTSTART;VALUE=DATE-TIME:20211208T200000Z
DTEND;VALUE=DATE-TIME:20211208T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/82
DESCRIPTION:Title: Quantum Root Vectors and a Dolbeault Double Complex for the A-Series Quan
tum Flag Manifolds\nby Réamonn Ó Buachalla (Charles University\, Pra
gue) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nIn the
2000s a series of seminal papers by Heckenberger and Kolb introduced an es
sentially unique covariant $q$-deformed de Rham complex for the irreducibl
e quantum flag manifolds. In the years since\, it has become increasingly
clear that these differential graded algebras have a central role to play
in the noncommutative geometry of Drinfeld–Jimbo quantum groups. Until n
ow\, however\, the question of how to extend Heckenberger and Kolb’s con
struction beyond the irreducible case has not been examined. Here we addre
ss this question for the A-series Drinfeld–Jimbo quantum groups $U_q(\\m
athfrak{sl}_{n+1})$\, and show that for precisely two reduced decompositio
ns of the longest element of the Weyl group\, Lusztig’s associated space
of quantum root vectors gives a quantum tangent space for the full quantu
m flag manifold $\\mathcal{O}_q(F_{n+1})$ with associated differential gra
ded algebra of classical dimension. Moreover\, its restriction to the quan
tum Grassmannians recovers the $q$-deformed complex of Heckenberger and Ko
lb\, giving a conceptual explanation for their origin. Time permitting\, w
e will discuss the noncommutative Kähler geometry of these spaces and the
proposed extension of the root space construction to the other series. (J
oint work with P. Somberg.)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/82/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Priyanga Ganesan (Texas A&M)
DTSTART;VALUE=DATE-TIME:20211215T200000Z
DTEND;VALUE=DATE-TIME:20211215T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/83
DESCRIPTION:Title: Spectral bounds for chromatic number of quantum graphs\nby Priyanga G
anesan (Texas A&M) as part of NYC noncommutative geometry seminar\n\n\nAbs
tract\nQuantum graphs are a non-commutative generalization of classical gr
aphs that have appeared in different branches of mathematics including ope
rator algebras\, non-commutative topology and quantum information theory.
In this talk\, I will review the different perspectives to quantum graphs
and introduce a chromatic number for quantum graphs using a non-local game
with quantum inputs and classical outputs. I will then show that many spe
ctral lower bounds for chromatic numbers in the classical case (such as Ho
ffman’s bound) also hold in the setting of quantum graphs. This is achie
ved using an algebraic formulation of quantum graph coloring and tools fro
m linear algebra.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/83/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yavar Abdolmaleki (University of New Brunswick)
DTSTART;VALUE=DATE-TIME:20220202T200000Z
DTEND;VALUE=DATE-TIME:20220202T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/84
DESCRIPTION:Title: Equivariant KK-theory and its application in Index theory\nby Yavar A
bdolmaleki (University of New Brunswick) as part of NYC noncommutative geo
metry seminar\n\n\nAbstract\nIn this talk\, we show how using the calculat
ion of a couple of Kasparov products of asymptotically equivariant cycles
we can find the index of an asymptotically equivariant Dirac-Schrodinger o
perator on a Hyperbolic manifold. In fact\,\nusing the calculation of the
Kasparov products of a couple of asymptotically equivariant cycles\, we re
duce the problem of finding the index to the\ncase in which the manifold i
s compact and so the problem reduces to the Atiyah-Singer index theorem.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/84/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Federico Vigolo (University of Münster)
DTSTART;VALUE=DATE-TIME:20220209T200000Z
DTEND;VALUE=DATE-TIME:20220209T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/85
DESCRIPTION:Title: Strong ergodicity\, projections and Markov operators\nby Federico Vig
olo (University of Münster) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nThe aim of this talk is to illustrate how some insights f
rom the theory of Markov processes can be adapted to prove that certain pr
ojections belong to "Roe-like" C*-algebras of dynamical origin. Given an a
ction of a countable discrete group on a measure space\, one may define a
C*-algebra by taking the closure of an algebra of operators with finite pr
opagation. I will explain that this C*-algebra contains a certain natural
family of rank-one projections if and only if the action is strongly ergod
ic. This result can be used to construct more counterexamples to the coars
e Baum-Connes conjecture.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/85/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ulrich Pennig (Cardiff University)
DTSTART;VALUE=DATE-TIME:20220216T200000Z
DTEND;VALUE=DATE-TIME:20220216T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/86
DESCRIPTION:Title: Bundles of C*-algebras - An Introduction to Dixmier-Douady theory\nby
Ulrich Pennig (Cardiff University) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nA bundle of C*-algebras is a collection of algebra
s continuously parametrised by a topological space. There are (at least) t
wo different definitions in operator algebras that make this intuition pre
cise: Continuous C(X)-algebras provide a flexible analytic point of view\,
while locally trivial C*-algebra bundles allow a classification via homot
opy theory. The section algebra of a bundle in the topological sense is a
C(X)-algebra\, but the converse is not true. In this talk I will compare t
hese two notions using the classical work of Dixmier and Douady on bundles
with fibres isomorphic to the compacts as a guideline. I will then explai
n joint work with Marius Dadarlat\, in which we showed that the theorems o
f Dixmier and Douady can be generalized to bundles with fibers isomorphic
to stabilized strongly self-absorbing C*-algebras. An important feature of
the theory is the appearance of higher analogues of the Dixmier-Douady cl
ass.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/86/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Damien Rivet (Université Clermont Auvergne)
DTSTART;VALUE=DATE-TIME:20220223T200000Z
DTEND;VALUE=DATE-TIME:20220223T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/87
DESCRIPTION:Title: Geometric view of semisimple quantum groups representations\nby Damie
n Rivet (Université Clermont Auvergne) as part of NYC noncommutative geo
metry seminar\n\n\nAbstract\nThe representations of the principal series o
f a semisimple quantum group can be\, as in the classical case\, construct
ed as induced representations from the characters of a quantum Borel subgr
oup. Rieffel's framework for induction can be adapted to quantum groups an
d allows to give a simple expression for the principal series representati
ons. In particular this leads\, as Clare did in the classical case\, to ga
ther all these representations into a single Hilbert module built from a c
ertain quantum homogeneous space.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/87/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Makoto Yamashita (University of Oslo)
DTSTART;VALUE=DATE-TIME:20220302T150000Z
DTEND;VALUE=DATE-TIME:20220302T160000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/88
DESCRIPTION:Title: Homology and K-theory of dynamical systems\nby Makoto Yamashita (Univ
ersity of Oslo) as part of NYC noncommutative geometry seminar\n\n\nAbstra
ct\nA theory of homology for étale groupoids was developed by Crainic and
Moerdijk based on simplicial structure of nerves of groupoids\, as a comp
anion to Haeflier's theory of cohomology for groupoids. We relate this to
another (co)homology of groupoids\, namely the operator K-groups of the as
sociated convolution algebra\, when the base is totally disconnected. Such
a connection was conjectured by Matui through his study of Cantor dynamic
al systems. Our proof is based on the triangulated categorical structure o
f groupoid equivariant KK-theory\, following the categorical approach to t
he Baum-Connes conjecture by Meyer and Nest. Along the way we uncover the
close connection to Putnam's homology theory for hyperbolic dynamical syst
ems (Smale spaces). Based on joint works with Valerio Proietti.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/88/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Fidaleo (Università di Roma "Tor Vergata")
DTSTART;VALUE=DATE-TIME:20220314T150000Z
DTEND;VALUE=DATE-TIME:20220314T160000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/89
DESCRIPTION:Title: Modular Spectral Triples and deformed Fredholm modules (Part I)\nby F
rancesco Fidaleo (Università di Roma "Tor Vergata") as part of NYC noncom
mutative geometry seminar\n\n\nAbstract\nDue to possible applications to t
he attempt to provide a set of equations which unify the four elementary i
nteractions in nature (the grand-unification) and in another\, perhaps con
nected\, direction in proving the long-standing\, still unsolved\, Riemann
conjecture about the zeroes of the $\\zeta$-function\, Connes’ non- com
mutative geometry grew up rapidly in the last decades.\n\nAmong the main o
bjects introduced (by A. Connes) for handling noncommutative geometry ther
e are the so called spectral triples\, encoding most of the properties enj
oyed by the (quantum) ”manifold” into consideration\, and the associat
ed Fredholm modules.\n\nOn the other hand\, the so-called Tomita modular t
heory is nowadays assuming an increasingly relevant role for several appli
cations in mathematics and in physics. Such a scenario suggests the necess
ary need to take the modular data into account in the investigation of qua
ntum manifolds. In such a situation\, the involved Dirac operators should
be suitably deformed (by the use of the modular operator)\, and should com
e from non-type $II_1$ representations.\n\nTaking into account such commen
ts\, we discuss the preliminary necessary step consisting in the explicit
construction of examples of non type $II_1$ representations and relative s
pectral triples\, called modular. This is done for the noncommutative 2-to
rus $A_{\\alpha}$\, provided α is a (special kind of) Liouville number\,
where the nontrivial modular structure plays a crucial role.\n\nFor such r
epresentations\, we briefly discuss the appropriate Fourier analysis\, by
proving the analogous of many of the classical known theorems in harmonic
analysis such as the Riemann-Lebesgue lemma\, the Hausdorff-Young theorem\
, and the $L_p$-convergence results associated to the Cesaro means (i.e. t
he Fejer theorem) and the Abel means reproducing the Poisson kernel. We sh
ow how those Fourier transforms ”diagonalise” appropriately some examp
les of the Dirac operators associated to the previous mentioned spectral t
riples.\n\nFinally\, we provide a definition of a deformed generalisation
of ”Fredholm module”\, i.e. a suitably deformed commutator of the ”p
hase” of the involved Dirac operator with elements of a subset (the so-c
alled Lipschitz $\\star$-algebra or Lipschitz operator system) which\, dep
ending on the cases under consideration\, is either a dense $\\star$-alge
bra or an essential operator system. We also show that all models of modul
ar spectral triples for the noncommutative 2-torus mentioned above enjoy t
he property to being also a deformed Fredholm module. This definition of d
eformed Fredholm module is new even in the usual cases associated to a tra
ce\, and could provide other\, hopefully interesting\, applications.\n\nTh
e present talk is based on the following papers:\n\n[1] F. Fidaleo and L.
Suriano: Type $III$ representations and modular spectral triples for the n
oncommutative torus\, J. Funct. Anal. 275 (2018)\, 1484-1531.\n\n[2] F. Fi
daleo: Fourier analysis for type III representations of the noncommutative
torus\, J. Fourier Anal. Appl. 25 (201)\, 2801-2835.\n\n[3] F. Ciolli and
F. Fidaleo: Type $III$ modular spectral triples and deformed Fredholm mod
ules\, preprint.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/89/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Fidaleo (Università di Roma "Tor Vergata")
DTSTART;VALUE=DATE-TIME:20220413T190000Z
DTEND;VALUE=DATE-TIME:20220413T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/90
DESCRIPTION:Title: Spectral actions for q-particles and their asymptotic (Part II)\nby F
rancesco Fidaleo (Università di Roma "Tor Vergata") as part of NYC noncom
mutative geometry seminar\n\n\nAbstract\nFor spectral actions made of the
average number of particles and arising from open systems made of general
free $q$-particles (including Bose\, Fermi and classical ones correspondin
g to $q=\\pm1$ and $0$\, respectively) in thermal equilibrium\, we compute
the asymptotic expansion with respect to the natural cut-off. We treat bo
th relevant situations relative to massless and massive particles\, where
the natural cut-off is $1/\\beta=k_{\\rm B}T$ and $1/\\sqrt{\\beta}$\, res
pectively. \nWe show that the massless situation enjoys less regularity p
roperties than the massive one. We also consider the passage to the contin
uum describing infinitely extended open systems in thermal equilibrium. We
briefly discuss the appearance of condensation phenomena occurring for Bo
se-like $q$-particles\, for which $q\\in(0\,1]$\, after passing to the con
tinuum. We also compare the arising results for the finite volume situatio
n (discrete spectrum) with the corresponding infinite volume one (continuo
us spectrum).\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/90/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward McDonald (PennState)
DTSTART;VALUE=DATE-TIME:20220323T190000Z
DTEND;VALUE=DATE-TIME:20220323T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/91
DESCRIPTION:Title: Littlewood-Paley inequalities and other analytic issues in noncommutative
Euclidean spaces\nby Edward McDonald (PennState) as part of NYC nonco
mmutative geometry seminar\n\n\nAbstract\nI will discuss some analytic iss
ues that arose in the course of investigations of the problem of character
ising quantum differentiability in noncommutative spaces. These issues hig
hlight some of the peculiar features of certain noncommutative spaces wher
e classical results become meaningless or trivially false. In particular I
discuss the apparent lack of a Poincaré inequality on noncommutative Euc
lidean planes (Moyal planes) and how this necessitates the use of new tech
niques.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/91/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Raphael Ponge (Sichuan University)
DTSTART;VALUE=DATE-TIME:20220330T190000Z
DTEND;VALUE=DATE-TIME:20220330T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/92
DESCRIPTION:Title: Dixmier trace formulas and negative eigenvalues of Schroedinger operators
on noncommutative tori\nby Raphael Ponge (Sichuan University) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nIn this talk\, we s
hall first address a question raised by Alain Connes during a conference a
t Fudan University in Shanghai in 2017. We will also explain a link that h
as come to light only recently between noncommutative geometry and the wor
k of Birman-Solomyak on semiclassical analysis of Schroedinger operators i
n the 70s. We will then present results obtained jointly with Ed McDonald
(UNSW-Sydney) on Cwikel-type estimates on NC tori. As an application we ob
tain a version of Connes' integration formulas under very weak assumptions
. Further applications include versions of the Cwikel-Lieb-Rozenblum and
Lieb-Thirring inequalities for negative eigenvalues of Schroedinger operat
ors on noncommutative tori. Ultimately\, we get a seminclassical Weyl law
for curved noncommutative tori\, i.e.\, NC tori endowed with arbitrary Rie
mannian metrics.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/92/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oleg Yu. Aristov (Moscow State University)
DTSTART;VALUE=DATE-TIME:20220406T140000Z
DTEND;VALUE=DATE-TIME:20220406T150000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/93
DESCRIPTION:Title: Complex analytic quantum groups\nby Oleg Yu. Aristov (Moscow State Un
iversity) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nWe
discuss a missing link in quantum group theory - quantum analogues of com
plex Lie groups. As such analogues\, I propose to take topological Hopf al
gebras with a finiteness condition (holomorphically ﬁnitely generated or
HFG for short). This approach is not directly related to C*-algebraic qua
ntum groups (at least for now) but is an alternative view. Nevertheless\,
the topic seems to offer a wide range of research opportunities.\n\nOur f
ocus is on examples\, such as analytic forms of some classical quantum gro
ups (a deformation of a solvable Lie group and Drinfeld-Jimbo algebras).
I also present some general results: 1) the category of Stein groups is a
nti-equivalent to the category of commutative Hopf HFG algebras\; 2) If $
G$ is a compactly generated Lie group\, the cocommutative topological Hop
f algebra $\\widehat{A(G)}$ (naturally associated with $G$) is HFG. Whe
n in addition\, $G$ is connected linear\, the structure of $\\widehat{A(G
)}$ can be described explicitly.\n\nI also plan to discuss briefly holomor
phic duality in the sense of Akbarov (which is parallel to Pontryagin dual
ity).\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/93/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karen Strung (Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220504T190000Z
DTEND;VALUE=DATE-TIME:20220504T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/94
DESCRIPTION:Title: An introduction to C*-algebras\, I\nby Karen Strung (Czech Academy of
Sciences) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nB
anach algebras\, definition of C*-algebra\, spectrum\, Gelfand transform\,
characters.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/94/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karen Strung (Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220511T190000Z
DTEND;VALUE=DATE-TIME:20220511T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/95
DESCRIPTION:Title: An introduction to C*-algebras\, II\nby Karen Strung (Czech Academy o
f Sciences) as part of NYC noncommutative geometry seminar\n\nAbstract: TB
A\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/95/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Benton Duncan (North Dakota State University)
DTSTART;VALUE=DATE-TIME:20220907T190000Z
DTEND;VALUE=DATE-TIME:20220907T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/96
DESCRIPTION:Title: Abstract operator algebras and enveloping C*-algebras\nby Benton Dunc
an (North Dakota State University) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nWe will consider nonselfadjoint operator algebras a
nd the $C^*$-algebras they generate. We will look at motivating examples o
f classes of nonselfadjoint operator algebras. We will outline several con
structions of enveloping $C^*$-algebras for operator algebras and develop
examples of the various enveloping $C^*$-algebras.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/96/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mariusz Tobolski (University of Wrocław)
DTSTART;VALUE=DATE-TIME:20220420T190000Z
DTEND;VALUE=DATE-TIME:20220420T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/97
DESCRIPTION:Title: Noncommutative numerable principal bundles from group actions on C*-algeb
ras\nby Mariusz Tobolski (University of Wrocław) as part of NYC nonco
mmutative geometry seminar\n\n\nAbstract\nThe notion of a compact noncommu
tative (or quantum) principal bundle\, which generalizes the Cartan compac
t principal bundle from topology (local triviality not assumed)\, emerged
in the literature almost 30 years ago. Recently\, the difficulty of introd
ucing the local-triviality condition to the noncommutative realm was overc
ome using the notion of the local-triviality dimension of an action of a c
ompact quantum group on a unital C*-algebra. In this talk\, I will propose
a definition of a locally trivial noncommutative principal bundle in the
setting of actions of locally compact Hausdorff groups on (possibly non-un
ital) C*-algebras. I will discuss various motivations and technical diffic
ulties that appear in the non-compact case. I will also provide some basic
results and examples. The key difference is that\, although the problem i
tself can be described in the language of C*-algebra\, one is quickly led
beyond the Gelfand-Naimark duality and to the theory of multipliers of the
Pedersen ideal.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/97/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karen Strung (Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220525T190000Z
DTEND;VALUE=DATE-TIME:20220525T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/99
DESCRIPTION:Title: An introduction to C*-algebras\, III\nby Karen Strung (Czech Academy
of Sciences) as part of NYC noncommutative geometry seminar\n\nAbstract: T
BA\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/99/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Slawomir Klimek (Indiana University–Purdue University Indianapol
is)
DTSTART;VALUE=DATE-TIME:20220427T190000Z
DTEND;VALUE=DATE-TIME:20220427T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/100
DESCRIPTION:Title: Smooth subalgebras in noncommutative geometry\nby Slawomir Klimek (I
ndiana University–Purdue University Indianapolis) as part of NYC noncomm
utative geometry seminar\n\n\nAbstract\nIn noncommutative geometry it is o
ften natural to consider dense *-subalgebras of C*-algebras in particular
in connection with cyclic cohomology or with the study of unbounded deriva
tions on C*-algebras.\nIf C*-algebras are thought of as generalizations of
topological spaces\, then dense subalgebras may be regarded as specifying
additional structures on the underlying space\, like a smooth structure.\
nAt present there is no universally accepted general theory of such smooth
subalgebras\, however there is a number of "standard" examples defined an
d studied in the literature.\nIn analogy with the algebras of smooth funct
ions on a compact manifold\, such a smooth subalgebra should have the foll
owing properties:\n(1) It should be closed under holomorphic functional ca
lculus of all elements and under smooth-functional calculus of self-adjoin
t elements\n(2) It should be complete with respect to a locally convex alg
ebra topology\nThe purpose of the talk is to discuss those concepts on exa
mples\, including some more recent constructions.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sherry Gong (Texas A&M University)
DTSTART;VALUE=DATE-TIME:20220601T190000Z
DTEND;VALUE=DATE-TIME:20220601T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/101
DESCRIPTION:Title: The Novikov conjecture\, operator K theory\, and diffeomorphism groups\nby Sherry Gong (Texas A&M University) as part of NYC noncommutative ge
ometry seminar\n\n\nAbstract\nIn this talk\, I will discuss some recent wo
rk on a version of the Novikov conjecture for certain subgroups of diffeom
orphism groups. This talk will be about joint work with Jianchao Wu\, Zhiz
hang Xie\, and Guoliang Yu.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/101/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bhishan Jacelon (Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220608T190000Z
DTEND;VALUE=DATE-TIME:20220608T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/102
DESCRIPTION:Title: Dynamical applications of C*-classification\nby Bhishan Jacelon (Cze
ch Academy of Sciences) as part of NYC noncommutative geometry seminar\n\n
\nAbstract\nBy the work of many mathematicians\, including Elliott\, Gong\
,\nLin and Niu\, the class of infinite-dimensional\, simple\, separable\nC
*-algebras that have finite nuclear dimension and satisfy the UCT can\nbe
classified by an invariant based on K-theory and traces. Insofar as\nthe t
heme of classification is pervasive throughout science in\ngeneral\, and (
noncommutative) topology in particular\, this result is\nan extraordinary
feat of mathematics. What's more\, it provides\npowerful machinery for the
analysis of the internal structure of\namenable C*-algebras. In this talk
\, I will explain one such\napplication: In the subclass of classifiable C
*-algebras consisting of\nthose for which the simplex of tracial states is
nonempty\, with\nextremal boundary that is compact and has the structure
of a connected\ntopological manifold\, automorphisms can be shown to be ge
nerically\ntracially chaotic. Using similar ideas\, I will show how certai
n stably\nprojectionless C*-algebras can be described as crossed products.
\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/102/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexey Kuzmin (University of Gothenburg)
DTSTART;VALUE=DATE-TIME:20220615T190000Z
DTEND;VALUE=DATE-TIME:20220615T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/103
DESCRIPTION:Title: Index theory of hypoelliptic operators on Carnot manifolds\nby Alexe
y Kuzmin (University of Gothenburg) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nWe study the index theory of hypoelliptic operator
s on Carnot manifolds -- manifolds whose Lie algebra of vector fields is e
quipped with a filtration induced from sub-bundles of the tangent bundle.
A Heisenberg pseudodifferential operator\, elliptic in the calculus of van
Erp-Yuncken\, is hypoelliptic and Fredholm. Under some geometric conditio
ns\, we compute its Fredholm index by means of operator K-theory. These re
sults extend the work of Baum-van Erp (Acta Mathematica '2014) for co-orie
nted contact manifolds to a methodology for solving this index problem geo
metrically on Carnot manifolds. Under the assumption that the Carnot manif
old is regular\, i.e. has isomorphic osculating Lie algebras in all fibres
\, and admits a flat coadjoint orbit\, the methodology derived from Baum-v
an Erp's work is developed in full detail. In this case\, we develop K-the
oretical dualities computing the Fredholm index by means of geometric K-ho
mology a la Baum-Douglas. The duality involves a Hilbert space bundle of f
lat orbit representations. Explicit solutions to the index problem for Toe
plitz operators and operators of the form "ΔH+γT" are computed in geomet
ric K-homology\, extending results of Boutet de Monvel and Baum-van Erp\,
respectively\, from co-oriented contact manifolds to regular polycontact m
anifolds.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/103/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhaoting Wei (Texas A&M-Commerce)
DTSTART;VALUE=DATE-TIME:20220914T190000Z
DTEND;VALUE=DATE-TIME:20220914T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/104
DESCRIPTION:Title: Equivariant K-theory on flag varieties of semisimple Lie groups\nby
Zhaoting Wei (Texas A&M-Commerce) as part of NYC noncommutative geometry s
eminar\n\n\nAbstract\nLet G be a real semisimple Lie group and X be the fl
ag variety of the complexification of G. Kashiwara proposed that there is
a deep connection between G-equivariant sheaves on X and the representatio
ns of G\, which plays the central role in geometric representation theory.
In this talk I will discuss a K-theoretic analogue of G-equivariant sheav
es\, namely G-equivariant K-theory on X. I will talk about attempts to com
pute such K-theory and its relation with the representation theory of G. I
will do some computation in special cases.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/104/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kathryn McCormick (CSU Long Beach)
DTSTART;VALUE=DATE-TIME:20220629T190000Z
DTEND;VALUE=DATE-TIME:20220629T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/105
DESCRIPTION:Title: Holomorphic subalgebras of $n$-homogeneous $C^*$-algebras\nby Kathry
n McCormick (CSU Long Beach) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nThere is a long tradition of analyzing $C^*$-algebras thr
ough topological invariants. One such result is Tomiyama and Takesaki's 19
61 proof that an $n$-homogeneous $C^*$-algebra is determined up to $*$-iso
morphism by an underlying continuous matrix bundle. Suppose that the base
space of the bundle is a bordered Riemann surface with finitely many smoot
h boundary components\, and the interior of the bundle is holomorphic. The
n for each such $n$-homogeneous $C^*$-algebra\, one can define a holomorph
ic subalgebra. In this talk\, we will describe some progress made towards
classifying these subalgebras up to complete isometric isomorphism based o
n their underlying bundles\, including some recent work with Jacob Cornejo
.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/105/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniele Alessandrini (Columbia University)
DTSTART;VALUE=DATE-TIME:20220921T190000Z
DTEND;VALUE=DATE-TIME:20220921T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/106
DESCRIPTION:Title: Non commutative cluster coordinates for Higher Teichmüller Spaces\n
by Daniele Alessandrini (Columbia University) as part of NYC noncommutativ
e geometry seminar\n\n\nAbstract\nIn higher Teichmuller theory we study su
bsets of the character varieties\nof surface groups that are higher rank a
nalogs of Teichmuller spaces\,\ne.g. the Hitchin components\, the spaces o
f maximal representations and\nthe other spaces of positive representation
s.\n\nFock-Goncharov generalized Thurston's shear coordinates and Penner's
\nLambda-lengths to the Hitchin components\, showing that they have a\nbea
utiful structure of cluster variety.\n\nWe applied a similar strategy to M
aximal Representations and we found new\ncoordinates on these spaces that
give them a structure of non-commutative\ncluster varieties\, in the sense
defined by Berenstein-Rethak. This is based on a joint\nwork with Guichar
d\, Rogozinnikov and Wienhard and one with Berenstein\, Rethak\,\nRogozinn
ikov and Wienhard.\n\nIn an project in progress we are generalizing these
coordinates to the other\nsets of positive representations\, using some to
ols we developed.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/106/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabor Etesi (Budapest University of Technology and Economics)
DTSTART;VALUE=DATE-TIME:20221026T190000Z
DTEND;VALUE=DATE-TIME:20221026T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/107
DESCRIPTION:Title: The universal von Neumann algebra of smooth four-manifolds revisited
\nby Gabor Etesi (Budapest University of Technology and Economics) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nMaking use of its s
mooth structure only\, out of a connected\noriented smooth $4$-manifold a
von Neumann algebra is constructed. As a\nspecial four dimensional phenome
non this von Neumann algebra contains\nalgebraic (i.e.\, formal or coming
from a metric) curvature tensors of the\nunderlying $4$-manifold and the v
on Neumann algebra itself is a\nhyperfinite factor of ${\\rm II}_1$-type h
ence is unique up to abstract\nisomorphisms of von Neumann algebras. Over
a fixed $4$-manifold this\nuniversal von Neumann algebra admits a particul
ar representation on a\nHilbert space such that its unitary equivalence cl
ass is preserved by\norientation-preserving diffeomorphisms consequently t
he Murray--von\nNeumann coupling constant of this representation is well-d
efined and gives\nrise to a new and computable real-valued smooth $4$-mani
fold invariant.\nIts link with Jones' subfactor theory is noticed as well
as computations\nin the simply connected closed case are carried out.\n\nA
pplication to the cosmological constant problem is also discussed.\nNamely
\, the aforementioned mathematical construction allows to reformulate\nthe
classical vacuum Einstein equation with cosmological constant over a\n$4$
-manifold as an operator equation over its tracial universal von\nNeumann
algebra such that the trace of a solution is naturally identified\nwith th
e cosmological constant. This framework permits to use the observed\nmagni
tude of the cosmological constant to estimate by topological means\nthe nu
mber of primordial black holes about the Planck era. This number\nturns ou
t to be negligable which is in agreement with known density\nestimates bas
ed on the Press--Schechter mechanism.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/107/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shirly Geffen (WWU Münster)
DTSTART;VALUE=DATE-TIME:20221102T190000Z
DTEND;VALUE=DATE-TIME:20221102T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/108
DESCRIPTION:Title: Dynamical comparison of amenable actions by non-amenable groups.\nby
Shirly Geffen (WWU Münster) as part of NYC noncommutative geometry semin
ar\n\n\nAbstract\nWe pull back boundary-type actions to paradoxical decomp
ositions of the acting group itself. \nIn particular\, we obtain strong pa
radoxical structure in non-elementary hyperbolic groups\, in many lattices
in Lie groups\, and in non-elementary Baumslag-Solitar groups.\nThis allo
ws us to show that whenever such groups admit a minimal amenable topologic
ally free action on a compact Hausdorff space\, the system has dynamical c
omparison and the attached crossed product is a purely infinite classifiab
le C*-algebra.\n\nThis is joint work with Eusebio Gardella\, Julian Kranz\
, and Petr Naryshkin.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/108/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Victor Nistor (Université de Lorraine)
DTSTART;VALUE=DATE-TIME:20221005T190000Z
DTEND;VALUE=DATE-TIME:20221005T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/110
DESCRIPTION:Title: Invariant differential operators acting on quotient spaces and their ind
ex\nby Victor Nistor (Université de Lorraine) as part of NYC noncommu
tative geometry seminar\n\n\nAbstract\nLet $G$ be a compact Lie group acti
ng on a smooth manifold $M$ (without \nboundar
y)\, $E \\to M$ be an equivariant bundle\, and $P$ be a $G$-invariant
\npseudodifferential operator acting on the sections
of $E$. Let $\\alpha$ \nbe an irreducible rep
resentation of $G$ and $\\pi_\\alpha(P)$ be the restriction
\nof $P$ to the isotypical component corresponding to $\\alpha$. We
study the \nresulting algebra of symbols and we
give a simple\, necessary and sufficient \ncriteri
on for $\\pi_\\alpha(P)$ to be Fredholm. We also provide a spectral
\nsequence converging to the periodic cyclic homology
of the corresponding \nalgebra of symbols. Thi
s work was done in collaboration with A. Baldare\,
\nM. Benameur\, R. Come\, and M. Lesch.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/110/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julian Kranz (WWU Münster)
DTSTART;VALUE=DATE-TIME:20220928T190000Z
DTEND;VALUE=DATE-TIME:20220928T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/111
DESCRIPTION:Title: K-theory of noncommutative Bernoulli shifts\nby Julian Kranz (WWU M
ünster) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nGiv
en a unital C*-algebra A and a discrete group G\, we consider the shift ac
tion of G on the infinite tensor product of G-many copies of A. In many ca
ses\, we are able to compute the K-theory of the associated reduced crosse
d product (for instance when A is finite-dimensional and G is amenable). T
he tools appearing include applications of the Baum-Connes conjecture and
elementary representation theory of finite groups. \nThis is joint work in
progress with S. Chakraborty\, S. Echterhoff and S. Nishikawa.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/111/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Frei (University of Copenhagen)
DTSTART;VALUE=DATE-TIME:20221012T190000Z
DTEND;VALUE=DATE-TIME:20221012T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/112
DESCRIPTION:Title: Operator algebras and quantum information: Connes implies Tsirelson and
robust self-testing\nby Alexander Frei (University of Copenhagen) as
part of NYC noncommutative geometry seminar\n\n\nAbstract\nWe give a very
simple proof of Connes implies Tsirelson\,\nand further advertise a hot to
pic in quantum information: optimal states and robust self-testing. We sho
wcase here how operator algebraic techniques can be quite fruitful.\n\nFor
this we begin with by recalling quantum strategies in the context of non-
local games\, and their description in terms of the state space on the ful
l group algebra of certain free groups.\n\nWith this description at hand\,
we then directly obtain the main result via an elementary lifting result
by Kim\, Paulsen and Schafhauser:\nthe Connes embedding problem implies th
e synchronous Tsirelson conjecture.\n\nAs such the entire proof is element
ary\,\nand bypasses all versions of Kirchberg's QWEP conjecture and the li
ke\,\nas well as any reformulation such as in terms of the micro state con
jecture.\n\nMoreover\, it should be (likely) easier to construct minimal n
onlocal games as counterexamples for the synchronous Tsirelson conjecture
(which is equivalent to the full Tsirelson conjecture but in a non-trivial
way) and so also nonamenable traces for above groups\, in other words non
-Connes embeddable operator algebras.\n\n\n\nAfter this we continue (as mu
ch as time permits) with an advertisement for one of the hottest topics in
quantum information:\ndevice-independent certification of quantum states\
, or in short ROBUST SELF-TESTING\,\nwhich has tremendous importance for t
he coming era of practical quantum computing.\nand we showcase how operato
r algebraic techniques can be quite fruitful here.\n\nMore precisely\, we
illustrate these techniques on the following two prominent classes of nonl
ocal games:\n\n1) The tilted CHSH game.\nWe showcase here how to compute t
he quantum value using operator algebraic techniques\, and how to use the
same to derive uniqueness for entire optimal states\, including all higher
moments as opposed to correlations defined on two-moments only\, where th
e latter compares to traditional self-testing.\nMoreover\, we report in th
is example on previously unknown phase transitions on the uniqueness of op
timal states when varying the parameters for the tilted CHSH game.\n\n2) T
he Mermin--Peres magic square and magic pentagram game.\nAs before\, we al
so note here uniqueness of optimal states\, which in these two examples is
a basically familiar result.\n\nThe first part is based on preprint: http
s://arxiv.org/abs/2209.07940\nThe second part on self-testing (and further
robust self-testing) is based on joint work with Azin Shahiri.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/112/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mario Klisse (TU Delft)
DTSTART;VALUE=DATE-TIME:20221019T190000Z
DTEND;VALUE=DATE-TIME:20221019T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/113
DESCRIPTION:Title: On the isomorphism class of q-Gaussian C*-algebras\nby Mario Klisse
(TU Delft) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nI
n 1991 Bozejko and Speicher introduced a non-commutative version of Browni
an motion by defining a family of algebras depending on a parameter −1
≤ q ≤ 1 that are nowadays commonly known as the q-Gaussian algebras. T
hese algebras interpolate between the extreme Bosonic case q = 1 and the F
ermionic case q = −1. For q = 0 they coincide with Voiculescu’s free G
aussians. The q-Gaussians can be studied on the level of *-algebras\, on t
he level of C*-algebras\, and on the level of von Neumann algebras. Wherea
s it is easily seen that in the *-algebraic setting the q-Gaussians all co
incide\, as soon as one passes to the operator algebraic level the questio
n for the dependence on the parameter q becomes notoriously difficult.\n\n
After introducing the necessary background on q-Gaussians\, by considering
the so-called Akemann-Ostrand property of the canonical inclusion we will
discuss the dependence of the isomorphism class of q-Gaussian C*-algebras
on the parameter q. This partially answers a question by Nelson and Zeng.
\n\nThe talk is baised on joint work with Matthijs Borst\, Martijn Caspers
and Mateusz Wasilewski.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/113/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sergii Bezuglyi (University of Iowa)
DTSTART;VALUE=DATE-TIME:20221115T190000Z
DTEND;VALUE=DATE-TIME:20221115T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/114
DESCRIPTION:Title: Dynamics and measures on generalized Bratteli diagrams\nby Sergii Be
zuglyi (University of Iowa) as part of NYC noncommutative geometry semina
r\n\n\nAbstract\nIn the talk\, I discuss measures on the path space of\nge
neralized Bratteli diagrams. We consider self-similar measures (called\nal
so IFS measures) on the path space of discrete and measurable Bratteli\ndi
agrams. In the literature\, similarity may be defined by systems of\naffin
e maps (Sierpinski) or systems of conformal maps (Julia). We study\nnew cl
asses of iterated function systems associated to stationary generalized\nB
ratteli diagrams. For the corresponding iterated function\nsystems\, we fu
rther identify the measures which are also shift-invariant.\nThe talk is b
ased on joint papers with Palle Jorgensen.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/114/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcin Marciniak (University of Gdansk)
DTSTART;VALUE=DATE-TIME:20221109T200000Z
DTEND;VALUE=DATE-TIME:20221109T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/115
DESCRIPTION:Title: Positive maps on operator algebras – some problems and some solutions<
/a>\nby Marcin Marciniak (University of Gdansk) as part of NYC noncommutat
ive geometry seminar\n\n\nAbstract\nIn the last decade\, the theory of pos
itive maps on operator algebras has gained increased importance as it has
been shown to have numerous applications in quantum information theory. We
will present an overview of the basic topics of this theory\, in particul
ar the characterization of extreme positive maps or the problem of decompo
sability. One of the intensively studied recently problems is the question
of the existence of entangled PPT states with high Schmidt number. In the
language of positive maps\, this is equivalent to the existence of indeco
mposable k-positive maps for large values of k.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/115/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Klaus Thomsen (Aarhus University)
DTSTART;VALUE=DATE-TIME:20221130T200000Z
DTEND;VALUE=DATE-TIME:20221130T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/116
DESCRIPTION:Title: The structure of KMS states for flows on an AF algebra\nby Klaus Tho
msen (Aarhus University) as part of NYC noncommutative geometry seminar\n\
n\nAbstract\nIn a recent work with George Elliott we have obtained a compl
ete description of the configurations of KMS states that occur for flows o
n a unital simple infinite dimensional AF algebra. The answer is that they
all do\, provided only that the simplex of 0-KMS states is affinely homeo
morphic to the tracial state space of the AF algebra\; a condition which i
s obviously necessary. In the talk I will explain the road to this conclus
ion\, which can be seen as the culmination of work and ideas that go back
more than 40 years and has involved very many mathematicians.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/116/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andre Kornell (Dalhousie University)
DTSTART;VALUE=DATE-TIME:20230125T200000Z
DTEND;VALUE=DATE-TIME:20230125T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/117
DESCRIPTION:Title: Categories of Hilbert spaces\nby Andre Kornell (Dalhousie University
) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nHilbert sp
aces form one category with bounded operators and another category with co
ntractions. I will present axioms for each of these two categories. These
axioms are interesting because they make no explicit reference to the real
number system. The proof appeals to Soler's theorem and to the theory of
dagger categories\, as well as to a few familiar results from operator the
ory.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/117/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikolai L. Vasilevski (CINVESTAV\, Mexico City)
DTSTART;VALUE=DATE-TIME:20230201T200000Z
DTEND;VALUE=DATE-TIME:20230201T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/118
DESCRIPTION:Title: Commutative algebras of Toeplitz operators on the disk: Spectral theorem
approach\nby Nikolai L. Vasilevski (CINVESTAV\, Mexico City) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nFor three standard m
odels of commutative algebras generated by Toeplitz\noperators in the weig
hted analytic Bergman space on he unit disk\, we\nfind their representatio
ns as the algebras of bounded functions of\ncertain unbounded self-adjoint
operators. We discuss main properties of\nthese representation and\, espe
cially\, describe relations between\nproperties of the spectral function o
f Toeplitz operators in the\nspectral representation and properties of the
symbols.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/118/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco D'Andrea (Università di Napoli Federico II)
DTSTART;VALUE=DATE-TIME:20230208T200000Z
DTEND;VALUE=DATE-TIME:20230208T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/120
DESCRIPTION:Title: CW structures in noncommutative geometry\nby Francesco D'Andrea (Uni
versità di Napoli Federico II) as part of NYC noncommutative geometry sem
inar\n\n\nAbstract\nI will illustrate some examples and ideas for a theory
of CW complexes in noncommutative geometry. In order to accommodate some
important examples\, instead of diagrams in the category of quantum spaces
(dual to C*-algebras) one is forced to work with a suitable homotopy cate
gory. In this category\, K-theory computations are made possible through t
he use of a Mayer-Vietoris sequence. The K-theory of a quantum space can b
e promoted from a plain abelian group to an augmented ring (in the sense o
f Cartan-Eilenberg)\, giving a finer topological invariant. The constructi
on of this invariant suggests a notion of "topology" and "continuity" in t
he quantum setting (a kind of Grothendieck topology). This is a work in pr
ogress in collaboration with P.M. Hajac\, T. Maszczyk\, A. Sheu\, and B. Z
ielinski.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/120/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christopher Wulff (University of Göttingen)
DTSTART;VALUE=DATE-TIME:20230215T200000Z
DTEND;VALUE=DATE-TIME:20230215T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/121
DESCRIPTION:Title: Generalized asymptotic algebras and E-theory for non-separable C*-algebr
as\nby Christopher Wulff (University of Göttingen) as part of NYC non
commutative geometry seminar\n\n\nAbstract\nMany common ad hoc definitions
of bivariant K-theory for\nnon-separable C*-algebras have some kind of dr
awback\, usually that one\ncannot expect the long exact sequences to hold
in full generality. I\nwill present a way to define E-theory for non-separ
able C*-algebras\nwithout such disadvantages via a generalized notion of a
symptotic\nalgebras. There is indication that canonical cycles of this new
model\nmight arise naturally in index theory on infinite dimensional mani
folds.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/121/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shanna Dobson (CSU Los Angeles)
DTSTART;VALUE=DATE-TIME:20230105T140000Z
DTEND;VALUE=DATE-TIME:20230105T150000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/122
DESCRIPTION:Title: Six Operations on Diamond Topos\nby Shanna Dobson (CSU Los Angeles)
as part of NYC noncommutative geometry seminar\n\n\nAbstract\nThis talk is
part of the Special Session on the Langlands Program\, JMM 2023 in Boston
\, MA.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/122/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marina Prokhorova (Technion)
DTSTART;VALUE=DATE-TIME:20230222T200000Z
DTEND;VALUE=DATE-TIME:20230222T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/123
DESCRIPTION:Title: Index theory of unbounded Fredholm operators\nby Marina Prokhorova (
Technion) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nIn
dex theory for norm continuous families of bounded Fredholm operators was
developed in the classical work of Atiyah\; its analog for self-adjoint op
erators was developed in the work of Atiyah and Singer. The index theory o
f elliptic differential operators on closed manifolds is based on these cl
assical results: one can pass from operators of positive order to operator
s of zeroth order\, and such a transformation is continuous.\n\nHowever\,
in other situations one needs to deal with weaker topologies on the space
of unbounded operators. For example\, for elliptic boundary value problems
on compact manifolds with boundary\, the graphs of corresponding unbounde
d operators depend continuously on parameter. The topology determined by p
assing from a closed operator to its graph is called the graph topology. T
he homotopy type of relevant spaces of unbounded Fredholm operators was de
termined by M. Joachim in 2003.\n\nMy talk is devoted to an index theory o
f graph continuous families of unbounded Fredholm operators in a Hilbert s
pace. I will show how this theory is related to the classical index theory
of bounded Fredholm operators. The talk is based on my recent preprints a
rXiv:2110.14359 and arXiv:2202.03337.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/123/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Feodor Kogan (University of Toronto)
DTSTART;VALUE=DATE-TIME:20230301T200000Z
DTEND;VALUE=DATE-TIME:20230301T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/124
DESCRIPTION:Title: Overview of Cartan subalgebras in operator algebras\nby Feodor Kogan
(University of Toronto) as part of NYC noncommutative geometry seminar\n\
n\nAbstract\nSimilar to the setting of Lie algebras\, a Cartan subalgebra
in a C*-algebra is a maximal abelian subalgebra with some additional prope
rties. Unlike the setting of Lie algebras Cartan subalgebras might not exi
st\, and if they do\, they are rarely unique. I will give an overview of o
ld and new results concerning Cartan subalgebras in C*-algebras with an em
phasis on their relation to groupoids.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/124/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christian Voigt (University of Glasgow)
DTSTART;VALUE=DATE-TIME:20230308T200000Z
DTEND;VALUE=DATE-TIME:20230308T210000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/125
DESCRIPTION:Title: Infinite quantum permutations\nby Christian Voigt (University of Gla
sgow) as part of NYC noncommutative geometry seminar\n\n\nAbstract\nQuantu
m symmetries feature naturally in the study of quantum groups\, subfactors
and quantum information. In this talk I will present an approach to study
quantum symmetries of infinite graphs. This leads to new examples of disc
rete quantum groups\, linking naturally with previous work in the case of
finite graphs. I will discuss a number of concrete examples\, and also hig
hlight some intriguing open problems.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/125/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Severino T. Melo (Universidade de São Paulo)
DTSTART;VALUE=DATE-TIME:20230315T190000Z
DTEND;VALUE=DATE-TIME:20230315T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/126
DESCRIPTION:Title: Pseudodifferential operators in strict deformation quantization\nby
Severino T. Melo (Universidade de São Paulo) as part of NYC noncommutativ
e geometry seminar\n\n\nAbstract\nMost of the talk will be about old resul
ts of H. O. Cordes\, Marcela Merklen and myself about characterizations of
pseudodifferential\noperators as smooth vectors for actions of the Heisen
berg group. Then I will announce related results recently obtained with Ro
drigo Cabral and Michael Forger\nabout a class of pseudodifferential opera
tors with $C^*$-algebra-valued symbols introduced by M. Rieffel in his con
struction of a "strict deformation\nquantization" for a $C^*$-algebra with
an action of $R^n$. We have proven the uniqueness of the $C^*$-norm for R
ieffel's (non complete) algebra and have\nalso proven a conjecture of Rief
fel which characterizes his pseudodifferential operators as the smooth vec
tors for an action of the Heisenberg group.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/126/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexei Yu. Pirkovskii (HSE Moscow)
DTSTART;VALUE=DATE-TIME:20230329T190000Z
DTEND;VALUE=DATE-TIME:20230329T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/127
DESCRIPTION:Title: Nonformal deformations of algebras of holomorphic functions\nby Alex
ei Yu. Pirkovskii (HSE Moscow) as part of NYC noncommutative geometry semi
nar\n\n\nAbstract\nFormal deformations of associative algebras are by now
classical and relatively well-studied objects. They were introduced by Ger
stenhaber in 1964\, and they are interesting especially because of their r
elation to deformation quantization. By contrast\, the theory of nonformal
deformations is now at a much earlier stage of development. Roughly\, a
general feature of all existing approaches to nonformal deformations\, whi
ch distinguishes them from formal deformations\, is that the role of the "
base" ring is now played by a certain algebra of functions (continuous\, o
r smooth\, or holomorphic...) rather than by the algebra of formal power s
eries. This makes nonformal deformations quite attractive from the physica
l point of view\, because they allow evaluating the deformed star product
at concrete nonzero values of the deformation parameter (Planck's constant
). In this talk\, our main objects will be nonformal (or\, more exactly\,
holomorphic) deformations of the algebras of holomorphic functions on the
polydisc and on the ball in $\\mathbb{C}^n$. We will discuss some properti
es of such deformations and their relation to formal deformations. If time
permits\, we will compare our approach to holomorphic deformations with S
. Waldmann's approach\, which is better adapted to deformation quantizatio
n\, but which applies only to some proper subalgebras of the algebras of h
olomorphic functions.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/127/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Elias G. Katsoulis (East Carolina University)
DTSTART;VALUE=DATE-TIME:20230419T190000Z
DTEND;VALUE=DATE-TIME:20230419T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/128
DESCRIPTION:Title: Isomorphisms and stable isomorphisms of non-selfadjoint operator algebra
s\nby Elias G. Katsoulis (East Carolina University) as part of NYC non
commutative geometry seminar\n\n\nAbstract\nIn this talk we address isomor
phisms and stable isomorphisms of various\nclasses of operator algebras. W
e state and resolve the isomorphism problem for\ntensor algebras of unital
multivariable dynamical systems. Specifically we show\nthat unitary equiv
alence after a conjugation for multi-variable dynamical systems\nis a comp
lete invariant for complete isometric isomorphisms between their tensor\na
lgebras. In particular\, this settles a conjecture of Davidson and Kakaria
dis relating\nto work of Arveson from the sixties\, and extends related wo
rk of Kakariadis and\nKatsoulis.\n\nWe also address stable isomorphism of
operator algebras\, in connection with a\nrecent work of Dor-On\, Eilers a
nd Geffen. Among others we show that if $\\mathcal{A}$\n and $\\mathcal{B}
$ are operator algebras with diagonals isomorphic to $c_0$ and \n$\\mathca
l{K}$ are the compact\noperators\, then $\\mathcal{A}\\otimes\\mathcal{K}$
and $\\mathcal{B}\\otimes\\mathcal{K}$\nare isometrically isomorphic if a
nd only if $\\mathcal{A}$ and\n$\\mathcal{B}$ are isometrically isomorphic
. If the algebras $\\mathcal{A}$ and $\\mathcal{B}$ satisfy an extra analy
ticity\ncondition\, a similar result holds with $\\mathcal{K}$ being repla
ced by any operator algebra\ncontaining the compact operators. Time permit
ting we will discuss other classes\nof operator algebras and their stable
isomorphisms\, including tensor algebras of\nmultivariable dynamical syste
ms.\n\nThe above results come from various projects with C. Ramsey\, E. Ka
kariadis\nand X. Lin.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/128/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anar Dosi (Middle East Technical University\, Cyprus)
DTSTART;VALUE=DATE-TIME:20230412T170000Z
DTEND;VALUE=DATE-TIME:20230412T180000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/129
DESCRIPTION:Title: Projective positivity of the function systems\nby Anar Dosi (Middle
East Technical University\, Cyprus) as part of NYC noncommutative geometry
seminar\n\n\nAbstract\nThe present talk is devoted to the projective posi
tivity in the category of function systems. It is an operator positivity o
ccurred in the quantization problems of the operator systems. It turns out
that every $∗$-(poly)normed topology compatible with a duality results
in the (local) projective positivity given by a filter base of the unital
cones with its separated intersection. We describe the (local) projective
positivity of the (local) $L^{p}$-spaces given by a bounded (or unbounded)
positive Radon measure on a locally compact topological space. The geomet
ry of the related state spaces is described in the case of $L^{p}$-spaces\
, Schatten matrix spaces\, and $L^{p}$-spaces of a finite von Neumann alge
bra.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/129/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitris Gerontogiannis (Leiden University)
DTSTART;VALUE=DATE-TIME:20230426T190000Z
DTEND;VALUE=DATE-TIME:20230426T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/130
DESCRIPTION:Title: Smale spaces and their dimension theory\nby Dimitris Gerontogiannis
(Leiden University) as part of NYC noncommutative geometry seminar\n\n\nAb
stract\nSmale spaces were defined by David Ruelle in the 1970's as topolog
ical models for the typically fractal-like hyperbolic nonwandering sets of
Stephen Smale's Axiom A systems. A Smale space is a compact metric space
together with a homeomorphism having exponential contraction and expansion
behaviour. Prototype examples are the topological Markov chains\, aperiod
ic substitution tilings and hyperbolic toral automorphisms. This talk will
give an example-driven introduction to Smale spaces with a focus on their
dimension theory\, which can be studied via Markov partitions and Ahlfors
regular measures. If time permits\, I will briefly mention how the dimens
ion theory of a Smale space is related to fine analytic properties of the
operator algebras encoding the stable and unstable foliations on it.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/130/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ali Raad (KU Leuven)
DTSTART;VALUE=DATE-TIME:20230517T190000Z
DTEND;VALUE=DATE-TIME:20230517T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/131
DESCRIPTION:Title: Inductive Limit Cartan Subalgebras\nby Ali Raad (KU Leuven) as part
of NYC noncommutative geometry seminar\n\n\nAbstract\nIn recent years the
interest for Cartan subalgebras in C*-algebras has risen due to new connec
tions found with topological dynamics and geometric group theory\, as well
as the classification programme for C*-algebras. For this\, the study of
Cartan subalgebras in inductive limit C*-algebras is fundamental. I will g
ive an overview of this topic as well as provide some new existence and un
iqueness results for inductive limit Cartan subalgebras.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/131/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ulrich Bunke (Universität Regensburg)
DTSTART;VALUE=DATE-TIME:20230524T190000Z
DTEND;VALUE=DATE-TIME:20230524T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/132
DESCRIPTION:Title: A homotopical view on $K$ and $KK$-theory for $C^{*}$-algebras\nby U
lrich Bunke (Universität Regensburg) as part of NYC noncommutative geomet
ry seminar\n\n\nAbstract\nThe goal of this talk is to motivate the conside
ration of spectrum-valued K-theory for $C^{*}$-algebras. To this end I wil
l discuss some examples where the spectrum-valued functor helps to simpli
fy classical statements and their justification. I will then explain how
to construct a spectrum-valued $K$-theory functor using a homotopical ref
inement of KK-theory. Accepting the language of $\\infty$-categories\, the
latter can be obtained in a straightforward way by forcing the desired
universal properties.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/132/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arthur Pander Maat (Queen Mary University)
DTSTART;VALUE=DATE-TIME:20230913T190000Z
DTEND;VALUE=DATE-TIME:20230913T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/133
DESCRIPTION:Title: Hilbert Modules over C*-categories\nby Arthur Pander Maat (Queen Mar
y University) as part of NYC noncommutative geometry seminar\n\n\nAbstract
\nC*-categories are a ‘horizontal categorification’ of C*-algebras\, a
nd they have a theory of Hilbert modules which generalizes that over C*-al
gebras. We go through some results about these modules\, culminating in an
Eilenberg-Watts theorem that characterizes which functors between module
categories are given by tensor products. We finish with some new work empl
oying this result\, along with work of Benjamin Duenzinger’s\, to exhibi
t a localization of the category of locally small C*-categories at the Mor
ita equivalences.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/133/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bernard Russo (UC Irvine)
DTSTART;VALUE=DATE-TIME:20230906T190000Z
DTEND;VALUE=DATE-TIME:20230906T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/134
DESCRIPTION:Title: Anti-$C^*$-algebras\nby Bernard Russo (UC Irvine) as part of NYC non
commutative geometry seminar\n\n\nAbstract\nWe introduce a class of Banach
algebras that we call\nanti-$C^*$-algebras. We show that the normed stan
dard embedding of a\n$C^*$-ternary ring is the direct sum of a $C^*$-algeb
ra and an\nanti-$C^*$-algebra. We prove that C*-ternary rings and anti-$C^
*$-algebras are\nsemisimple. We give two new characterizations of $C^*$-te
rnary rings which\nare isomorphic to a TRO (ternary ring of operators)\, p
roviding answers\nto a query raised by Zettl in 1983\, and we propose some
problems for\nfurther study. (Joint work with Robert Pluta)\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/134/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gihyun Lee (Ghent University)
DTSTART;VALUE=DATE-TIME:20230920T190000Z
DTEND;VALUE=DATE-TIME:20230920T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/135
DESCRIPTION:Title: $L_p$-bounds for pseudodifferential operators on curved noncommutative t
ori\nby Gihyun Lee (Ghent University) as part of NYC noncommutative ge
ometry seminar\n\n\nAbstract\nIn the theory of pseudodifferential operator
s\, one of the most essential topics is the study of mapping properties of
pseudodifferential operators between various kinds of function spaces. Th
e investigation of $L_p$-boundedness of pseudodifferential operators is pa
rticularly important\, considering its consequences for the regularity and
existence of solutions of PDEs.\n\nThe purpose of this talk is to discuss
the counterpart of this problem on noncommutative tori. Noncommutative to
ri are the most intensively studied noncommutative spaces in noncommutativ
e geometry and arise in various parts of mathematics and mathematical phys
ics. Pseudodifferential calculus on noncommutative tori was introduced in
early 1980s by A. Connes\, and it has emerged as an indispensable tool in
the recent study of differential geometry of noncommutative tori. Meanwhil
e\, J. Rosenberg introduced the notion of Riemannian metric on noncommutat
ive tori a decade ago. In this talk\, I will first recall the notion of a
curved noncommutative torus\, i.e.\, a noncommutative torus endowed with a
Riemannian metric in the sense of J. Rosenberg. I will then show the boun
dedness of pseudodifferential operators on noncommutative $L_p$-spaces ass
ociated with the volume form induced by a Riemannian metric. Based on join
t work with V. Kumar.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/135/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pawel Sarkowicz (University of Ottawa)
DTSTART;VALUE=DATE-TIME:20230927T190000Z
DTEND;VALUE=DATE-TIME:20230927T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/136
DESCRIPTION:Title: Tensorially absorbing inclusions of C*-algebras\nby Pawel Sarkowicz
(University of Ottawa) as part of NYC noncommutative geometry seminar\n\n\
nAbstract\nWe introduce the notion of a tensorially absorbing inclusion --
that is\, when an inclusion absorbs a strongly self-absorbing C*-algebra
in a suitable way. We discuss various properties\, central sequence charac
terizations\, give examples and non-examples\, and provide some applicatio
ns and natural open questions.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/136/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charlie Beil (University of Graz)
DTSTART;VALUE=DATE-TIME:20231004T190000Z
DTEND;VALUE=DATE-TIME:20231004T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/137
DESCRIPTION:Title: Nonnoetherian geometry\, noncommutative desingularizations\, and quantum
theory\nby Charlie Beil (University of Graz) as part of NYC noncommut
ative geometry seminar\n\n\nAbstract\nI will introduce a new kind of geome
try that arises from nonnoetherian subalgebras of polynomial rings\, and\,
more generally\, coordinate rings of affine varieties. In this constructi
on\, points may be 'smeared-out' and have positive dimension. I will then
describe an application of this geometry to a class of noncommutative alge
bras defined by oriented graphs in surfaces\, called dimer and ghor algebr
as. The geometry allows these algebras to be viewed as noncommutative desi
ngularizations of their centers\, and yields relationships between their r
epresentation theory and the surface topology. Finally\, I will sketch an
application of the geometry to a new spacetime model of spin and its wave
function collapse.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/137/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joakim Arnlind (Linköping University)
DTSTART;VALUE=DATE-TIME:20231011T190000Z
DTEND;VALUE=DATE-TIME:20231011T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/138
DESCRIPTION:by Joakim Arnlind (Linköping University) as part of NYC nonco
mmutative geometry seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/138/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wade Bloomquist (Morningside University)
DTSTART;VALUE=DATE-TIME:20231018T190000Z
DTEND;VALUE=DATE-TIME:20231018T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/139
DESCRIPTION:by Wade Bloomquist (Morningside University) as part of NYC non
commutative geometry seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/139/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jesse Peterson (Vanderbilt University)
DTSTART;VALUE=DATE-TIME:20231101T190000Z
DTEND;VALUE=DATE-TIME:20231101T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/140
DESCRIPTION:Title: Biexact groups and von Neumann algebras\nby Jesse Peterson (Vanderbi
lt University) as part of NYC noncommutative geometry seminar\n\n\nAbstrac
t\nThe notion of biexactness for groups was introduced by Ozawa in 2004 an
d has since become one of the major tools for studying decomposability pro
perties for von Neumann algebras. I will survey the development of biexact
ness over the last two decades\, and I will discuss a joint project with C
hangying Ding where we introduce biexact von Neumann algebras and frame ma
ny of these results in this more general setting.\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/140/
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. Christopher Phillips (University of Oregon)
DTSTART;VALUE=DATE-TIME:20231025T190000Z
DTEND;VALUE=DATE-TIME:20231025T200000Z
DTSTAMP;VALUE=DATE-TIME:20230926T001655Z
UID:NYC-NCG/141
DESCRIPTION:by N. Christopher Phillips (University of Oregon) as part of N
YC noncommutative geometry seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/NYC-NCG/141/
END:VEVENT
END:VCALENDAR