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BEGIN:VEVENT
SUMMARY:Eske Ewert (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20200527T081500Z
DTEND;VALUE=DATE-TIME:20200527T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/1
DESCRIPTION:Title: Pseudodifferential calculi and generalised fixed point algebras\
nby Eske Ewert (Universität Göttingen) as part of Göttingen Seminar Non
commutative Geometry\n\n\nAbstract\nIn this talk\, I will explain an appro
ach to pseudo-differential calculi using generalized fixed point algebras.
\nAs an interesting instance\, we will consider the calculus for filtered
manifolds that was developed by van Erp and Yuncken. Here\, vector fields
can have order higher than one when understood as differential operators.
This induces a “zoom”-action of the positive real numbers on the tange
nt groupoid of the filtered manifold. The C*-algebra of order zero pseudo-
differential operators can be described as a generalized fixed point algeb
ra with respect to this action.\nThis is part of my PhD project which is s
upervised by Prof. Ralf Meyer and Prof. Ryszard Nest.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rohan Jotz-Lean (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20200603T081500Z
DTEND;VALUE=DATE-TIME:20200603T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/2
DESCRIPTION:Title: Bivariant K-theory as a stable ∞-category\nby Rohan Jotz-Lean
(Universität Göttingen) as part of Göttingen Seminar Noncommutative Geo
metry\n\n\nAbstract\nA brief introduction of ∞-categories is followed by
a concrete construction of a stable ∞-category that truncates to Kaspar
ov's bivariant K-theory. The construction is compatible with various addi
tional structures on C*-algebras (or pro-C*-algebras)\, and it has a pract
ical universal property that can be used\, for example\, to define a monoi
dal structure.\n\nNo prior knowledge of K-theory is required.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christoph Sieling
DTSTART;VALUE=DATE-TIME:20200610T081500Z
DTEND;VALUE=DATE-TIME:20200610T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/3
DESCRIPTION:Title: K-theory of Cuntz-Pimsner Algebras\nby Christoph Sieling as part
of Göttingen Seminar Noncommutative Geometry\n\n\nAbstract\nThis seminar
talk presents the results of my Bachelor's thesis. We will introduce the
notion of a C*-correspondence and construct the Toeplitz algebra by opera
tors on the Fock space. Furthermore\, we define the (relative) Cuntz-Pims
ner algebra and see that it generalizes graph-C*-algebras and crossed prod
ucts by Z. One of the main tools for computing the K-theory of these algeb
ras is the 6-term exact sequence of Pimsner. We will give the main points
of this proof.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Celso Antunes
DTSTART;VALUE=DATE-TIME:20200617T081500Z
DTEND;VALUE=DATE-TIME:20200617T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/4
DESCRIPTION:Title: KMS states on the groupoid model for a groupoid correspondence\n
by Celso Antunes as part of Göttingen Seminar Noncommutative Geometry\n\n
\nAbstract\nKMS-states are important objects of study in operator algebras
. In physics where operators on Hilbert spaces are used to model quantum s
ystems\, KMS-states are understood as equilibrium states of the system. Th
ese ideas can be generalized to C*-algebras and in particular on the speci
fic class of C*-algebras that have a groupoid model\, KMS-states relate to
quasi-invariant measures on the unit space of the groupoid model. Groupoi
d correspondences are a generalization of topological graphs\, self-simila
r groups and self-similar graphs. A groupoid correspondence gives rise to
a C*-correspondence\, on which we can use the Cuntz-Pimsner construction t
o generate a single C*-algebra. The Cuntz-Pimsner algebra for this C*-corr
espondence is a C*-algebra of a groupoid\, which we call the groupoid mode
l for the groupoid correspondence. The unit space of this groupoid model i
s still quite complicated to work with\, which makes finding quasi-invaria
nt measures on it also complicated. We proved that this is equivalent to a
certain quasi-invariance relation on measures on the unit space of the in
itial groupoid\, simplifying the study of these measures\, and therefore K
MS-states for these C*-algebras.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Li Yuezhao
DTSTART;VALUE=DATE-TIME:20200708T081500Z
DTEND;VALUE=DATE-TIME:20200708T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/6
DESCRIPTION:Title: Coarse Mayer-Vietoris Sequence and Bulk-Edge Correspondence\nby
Li Yuezhao as part of Göttingen Seminar Noncommutative Geometry\n\n\nAbst
ract\nRoe C*-algebras are models of topological insulators. The bulk inva
riants are given by their K-theory. The bulk-edge correspondence claims t
hat non-trivial bulk invariants lead to the existence of edge states. In
a recent preprint\, Ludewig and Thiang constructed an integer-valued map t
o compute the bulk invariants and proved that the spectral gap closes if t
he map is non-zero. They used a partition of the space\, but showed also
that the map does not depend much on the partition.\n\nIn this talk\, I wi
ll show that the map defined by Ludewig and Thiang agrees with a compositi
on of boundary maps in coarse Mayer-Vietoris sequences. The insensitivity
to partitions is a consequence of the naturality of the coarse Mayer-Viet
oris sequence. The boundary maps in coarse Mayer-Vietoris sequences descr
ibe the bulk-edge correspondence. These results can be generalised to hig
her-dimensional spaces.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Frei (University of Copenhagen)
DTSTART;VALUE=DATE-TIME:20200722T081500Z
DTEND;VALUE=DATE-TIME:20200722T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/8
DESCRIPTION:Title: Gauge-invariant uniqueness theorems\, revisited\nby Alexander Fr
ei (University of Copenhagen) as part of Göttingen Seminar Noncommutative
Geometry\n\n\nAbstract\nWe give a seemingly new and conceptual treatment
of the gauge-invariant uniqueness theorem (in short\, gauge theorems) and
its consequences. Its novelty is to treat all relative Cuntz-Pimsner alg
ebras (including and beyond Katsura's ideal) for all gauge-invariant repre
sentations simultaneously\, and its proof improves upon a proof by inducti
on due to Evgenios Kakariadis\, and reduces the problem to its heart: the
Fell bundles.\n\nFor this\, we also separate the goal to prove the gauge-e
quivariant uniqueness theorems from the task to identify kernel\, covarian
ce and associated ideal for relative Cuntz-Pimsner representations. This
separation of tasks highlights the algebraic treatment from when the analy
sis of the Fock representation becomes accomodating.\n\nIncidentally\, its
proof renders any deeper analysis of cores completely redundant. This in
cludes also results beyond the gauge-equivariant uniqueness theorems\, as
for example nuclearity or the PV six-term exact sequence.\n\nSecond part:\
nFollowing from there\, its corollaries then identify the kernel\, covaria
nce and associated ideal of relative Cuntz-Pimsner representations and est
ablish the Cuntz-Pimsner short exact sequence — now using the Fock repre
sentation due to the previously established gauge-equivariant uniqueness t
heorems. We will also discover obstructions here for (not necessarily gau
ge-equivariant) representations to admit any faithful embedding of relativ
e Cuntz-Pimsner algebras. And as another application\, we will work out t
he detection of ideals property.\n\nOutlook:\nAs a next point\, the speake
r aims to find a more conceptual treatment of Katsura's results on the lat
tice of gauge-invariant ideals\, and as a future goal\, the speaker aims t
o generalise these results to product systems.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Devarshi Mukherjee (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20201102T131500Z
DTEND;VALUE=DATE-TIME:20201102T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/9
DESCRIPTION:Title: Generalised Hochschild-Kostant-Rosenberg Theorems\nby Devarshi M
ukherjee (Universität Göttingen) as part of Göttingen Seminar Noncommut
ative Geometry\n\n\nAbstract\nThe HKR theorem is a fundamental theorem rel
ating Hochschild homology and de Rham cohomology. In its most basic form\,
the theorem states that for smooth commutative algebras\, Hochschild homo
logy groups are isomorphic to Kähler differentials. This result has since
been generalised to various non-smooth and non-affine scheme theoretic co
ntexts. In this talk\, I will build up from the basic HKR theorem for smoo
th algebras to recent work by Toën-Vezzosi that proves a very general ver
sion of HKR. I will conclude by mentioning an ongoing project with Kobi Kr
emnizer and Jack Kelly that seeks to use Toën-Vezzosi's methods to prove
an analytic version of HKR using certain exact categories that arise in de
rived analytic geometry.\n\nI plan to make the talk accessible to a non-co
mmutative geometry audience and recall all relevant definitions.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Taylor (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20201123T131500Z
DTEND;VALUE=DATE-TIME:20201123T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/10
DESCRIPTION:Title: Weak Cartan inclusions following Exel and Pitts\nby Jonathan Ta
ylor (Universität Göttingen) as part of Göttingen Seminar Noncommutativ
e Geometry\n\n\nAbstract\nGiven a nice enough inclusion A into B of C*-alg
ebras\, can we describe B in terms of its dynamics on A? In 2008 Renault g
ave an answer to this: yes\, if the conditions are nice enough\, one can d
escribe the inclusion using a twisted groupoid C*-algebraic model. Renault
called an inclusion satisfying these conditions “Cartan”. \nThere hav
e been a number of advancements in this field since then\, working at weak
ening the conditions in Renault's original paper while presenting similar
results. In this seminar I will talk about one such paper by Exel and Pitt
s from 2019\, working to weaken conditions on the inclusion from Renault's
initial paper\; particularly the existence of a conditional expectation\,
and the maximal abelian property of A.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:George Nadareishvili (Tbilisi State University)
DTSTART;VALUE=DATE-TIME:20201221T131500Z
DTEND;VALUE=DATE-TIME:20201221T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/11
DESCRIPTION:Title: Approximation of KK-theory of type I C*-algebras with finite group
actions by Mackey functors for twists\nby George Nadareishvili (Tbilis
i State University) as part of Göttingen Seminar Noncommutative Geometry\
n\n\nAbstract\nIn this talk\, we will modify a familiar notion of Mackey f
unctors from representation theory\, by extending them to encompass projec
tive representations of finite groups and use them to find K-theoretic app
roximations of equivariant KK-theory of type I C*-algebras with finite gro
up actions.\nThis is ongoing joint work with Ralf Meyer\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Celso Antunes (Göttingen University)
DTSTART;VALUE=DATE-TIME:20210111T131500Z
DTEND;VALUE=DATE-TIME:20210111T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/12
DESCRIPTION:by Celso Antunes (Göttingen University) as part of Göttingen
Seminar Noncommutative Geometry\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonas Luckhardt (Göttingen University)
DTSTART;VALUE=DATE-TIME:20210118T131500Z
DTEND;VALUE=DATE-TIME:20210118T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/13
DESCRIPTION:Title: Convolution of measures on locally compact groupoids\nby Jonas
Luckhardt (Göttingen University) as part of Göttingen Seminar Noncommuta
tive Geometry\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuezhao Li (Göttingen University)
DTSTART;VALUE=DATE-TIME:20210125T131500Z
DTEND;VALUE=DATE-TIME:20210125T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/14
DESCRIPTION:Title: Bulk indices of topological insulators modelled by Roe C*-algebras<
/a>\nby Yuezhao Li (Göttingen University) as part of Göttingen Seminar N
oncommutative Geometry\n\n\nAbstract\nRoe C*-algebras are models of disord
ered topological insulators. When we consider systems with symmetries\, we
should tensor the real or complex Roe C*-algebras with a real or complex
Clifford algebra\, which gives real or complex graded C*-algebras. Their v
an Daele K-theory classes are called symmetry protected topological phases
\, briefly SPT. Using a partition of the space\, Roe C*-algebras have coar
se Mayer-Vietoris sequences in van Daele's K-theory. The Mayer-Vietoris bo
undary maps model the bulk-edge correspondences. Compositions of these ma
p an SPT phase to a Z- or Z/2-valued index.\n\nIn this talk\, we will firs
t introduce topological insulators protected by symmetries\, and show how
to use van Daele's K-theory to classify their topological phases. Then we
use the coarse Mayer-Vietoris sequence to obtain a bulk index of SPT phase
s\, and explain the Z/2-index of class AII topological insulators in dimen
sion 3. In the end\, we will use tools from coarse geometry to give some
example where the Mayer-Vietoris boundary maps are isomorphisms.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Held (Göttingen University)
DTSTART;VALUE=DATE-TIME:20210201T131500Z
DTEND;VALUE=DATE-TIME:20210201T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/15
DESCRIPTION:Title: Second adjointness for reductive p-adic groups\nby Jan Held (G
öttingen University) as part of Göttingen Seminar Noncommutative Geometr
y\n\n\nAbstract\nLet $G$ be a connected reductive $\\mathfrak p$-adic grou
p. A representation $\\pi \\colon G \\to \\operatorname{Aut}_k(V)$ is smoo
th if the stabliser of each vector is open in $G.$ The category of smooth
representations of $G$ is isomorphic to the category of smooth (non-degene
rate) modules over the convolution algebra $A = \\mathcal D(G)$ of locally
constant\, compactly supported functions $f \\colon G \\to k.$ \n\nIf $P
= MN \\subset G$ is a parabolic subgroup of $G$ with Levi subgroup $M$ und
unipotent radical $N\,$ then $M$ is again a connected reductive $\\mathfr
ak p$-adic group\, and one considers the functors $r_M$ and $i_M$ of parab
olic restriction and induction\, respectively. There is a form of Frobeniu
s reciprocity between these functors: $i_M$ is canonically right adjoint t
o $r_M.$ It is a harmless-looking\, but deep result by J. N. Bernstein\, c
alled Second Adjointness\, that $i_M$ is also left adjoint to $\\bar r_M\,
$ parabolic restriction with respect to the opposite parabolic subgroup $\
\bar P = M\\bar N.$\n\nIn this talk\, we shall recall some notions and the
n speak about an attempt to construct a proof of Second Adjointness by way
of smooth modules.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Camila Fabre Sehnem (Victoria University of Wellington)
DTSTART;VALUE=DATE-TIME:20210208T131500Z
DTEND;VALUE=DATE-TIME:20210208T144500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/16
DESCRIPTION:Title: Toeplitz algebras of semigroups\nby Camila Fabre Sehnem (Victor
ia University of Wellington) as part of Göttingen Seminar Noncommutative
Geometry\n\n\nAbstract\nThe Toeplitz C*-algebra $\\mathcal{T}_\\lambda(P)
$ of a left cancellative monoid $P$ is the C*-algebra generated by the lef
t regular representation of $P$ by isometries on $\\ell^2(P)$. When a char
acterisation of $\\mathcal{T}_\\lambda(P)$ via a universal property for ge
nerators and relations is possible\, and conditions are given for faithful
ness of representations\, one obtains what is known as a uniqueness theore
m\, as in celebrated results of Coburn\, Douglas and Cuntz. Li introduced
a C*-algebra for an arbitrary submonoid of a group via generators and rela
tions in a far-reaching generalisation of the C*-algebras associated to po
sitive cones of quasi lattice orders by Nica and of the Toeplitz-type C*-a
lgebras associated to algebraic number fields. His C*-algebra is canonical
ly isomorphic to $\\mathcal{T}_\\lambda(P)$ for $P$ in a large class of mo
noids\, but this is never the case if $P$ does not satisfy a certain indep
endence condition. I will report on recent work with M. Laca\, in which we
define a universal Toeplitz C*-algebra $\\mathcal{T}_u(P)$ via generators
and relations that is canonically isomorphic to Li's semigroup C*-algebra
when independence holds and works as it should when independence fails. I
will address faithfulness of representations and uniqueness theorems for
Toeplitz C*-algebras\, presenting results that are new also for monoids th
at satisfy independence. If time permits\, I intend to give a concrete pre
sentation for the covariance algebra of the canonical product system over
$P$ with one-dimensional fibres using a notion of foundation sets and to e
xplain why this C*-algebra may be viewed as a universal analogue of the bo
undary quotient of $\\mathcal{T}_\\lambda(P)$.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey-Desmond Busche (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20210505T121500Z
DTEND;VALUE=DATE-TIME:20210505T134500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/17
DESCRIPTION:Title: An algebraic view on differential operators and their adjoints\
nby Geoffrey-Desmond Busche (Universität Göttingen) as part of Göttinge
n Seminar Noncommutative Geometry\n\n\nAbstract\nA classical object of int
erest in manifold and groupoid theory are differential operators. This ta
lk first introduces differential operators on manifolds in different ways\
, depending more or less on the choice of coordinates. The main result ch
aracterises which *-algebra structures on the algebra of differential oper
ators come from the adjoint operator on the L²-space for a volume form.
In the end\, we carry this over to the algebra of invariant differential o
perators on a Lie groupoid.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Devarshi Mukherjee (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20210512T121500Z
DTEND;VALUE=DATE-TIME:20210512T134500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/18
DESCRIPTION:Title: Bornological Hochschild-Kostant-Rosenberg Theorem\nby Devarshi
Mukherjee (Universität Göttingen) as part of Göttingen Seminar Noncommu
tative Geometry\n\n\nAbstract\nLet R be a Banach ring. We prove that the c
ategory of chain complexes of complete bornological R-modules (and several
related categories) are homotopy and derived algebraic contexts in the se
nse of Toen-Vezzosi and Raksit. We then use the framework of derived algeb
ra to prove a general version of the HKR Theorem\, which in particular rel
ates the circle action on the Hochschild algebra to the de Rham-differenti
al- enriched-de Rham algebra of a simplicial\, commutative\, complete born
ological algebra. This has a geometric interpretation in the language of d
erived analytic geometry\, namely\, the derived loop stack of a derived an
alytic stack is equivalent to the shifted tangent stack. These observation
s are part of joint work-in-progress with Jack Kelly and Kobi Kremnizer.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Taylor (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20210519T121500Z
DTEND;VALUE=DATE-TIME:20210519T134500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/19
DESCRIPTION:Title: Morphisms between Cartan subalgebras and their underlying twisted g
roupoids\nby Jonathan Taylor (Universität Göttingen) as part of Göt
tingen Seminar Noncommutative Geometry\n\n\nAbstract\nIn his 2008 paper\,
Renault firmly established the one-to-one correspondence between Cartan pa
irs of C*-algebras and twisted étale Hausdorff essentially principal grou
poids. One may then ask the question\, what are the appropriate morphisms
to consider between such twisted groupoids to induce useful morphisms betw
een Cartan pairs (or vice versa)? In this talk\, I will give some possible
answers to this question from the work of Li\, Buneci-Stachura\, and Meye
r-Zhu. Li's work shows equivalence of injective *-homomorphisms between th
e Cartan pairs with existence of an intermediate twisted groupoid 'between
' the two Weyl groupoids. Buneci-Stachura and Meyer-Zhu introduce new morp
hisms between categories of groupoid actions\, called 'actors'\, and show
that these induce actions (i.e. multiplier valued *-homomorphisms) on the
corresponding groupoid C*-algebras. This can easily be extended to twisted
groupoids and their C*-algebras.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jack Kelly
DTSTART;VALUE=DATE-TIME:20210526T121500Z
DTEND;VALUE=DATE-TIME:20210526T134500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/20
DESCRIPTION:Title: Bornological Spectra\nby Jack Kelly as part of Göttingen Semin
ar Noncommutative Geometry\n\n\nAbstract\nIn this talk we introduce the mo
noidal (infinity\,1)-category of bornological spectra. We define the borno
logical homotopy groups of bornological spectra\, and what it means for a
bornological spectrum to be complete. Following work of Durov\, Mihara\, a
nd Paugam we define topological Hochschild homology and periodic cyclic ho
mology of bornological ring spectra\, and explain how one can globalise th
ese definitions to obtain invariants of analytic spaces. This is part of w
ork in progress with Federico Bambozzi\, Oren Ben-Bassat\, Kobi Kremnizer
and Devarshi Mukherjee.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oren Ben-Bassat (University of Haifa)
DTSTART;VALUE=DATE-TIME:20210616T121500Z
DTEND;VALUE=DATE-TIME:20210616T134500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/21
DESCRIPTION:Title: Homotopy Epimorphisms and Banach Algebraic Geometry\nby Oren Be
n-Bassat (University of Haifa) as part of Göttingen Seminar Noncommutativ
e Geometry\n\n\nAbstract\nI will start by talking about homotopy epimorphi
sms of ring-ish objects in different areas of mathematics. These include K
ontsevich's approach to non-commutative geometry and derived and homotopy
algebraic geometry as in the work of Lurie\, Toen and Vezzosi. From here\,
I will transition into (commutative\, derived) analytic geometry. I will
present a general form of algebraic geometry relative to the category of B
anach abelian groups. I will try to give examples of interest in complex a
nd p-adic analytic geometry\, and even to an analytic viewpoint on arithme
tic geometry.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taeyoung Lee (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20210908T101500Z
DTEND;VALUE=DATE-TIME:20210908T114500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/22
DESCRIPTION:Title: A bicategorical view on group actions on rings\nby Taeyoung Lee
(Universität Göttingen) as part of Göttingen Seminar Noncommutative Ge
ometry\n\n\nAbstract\nIn this talk\, We will consider the bicategory $\\ma
thfrak{Rings}$ which has rings as objects\, $S\,R$-bimodules as arrows $S
\\leftarrow R$\, and bimodule maps between them as 2-arrows. We discuss a
generalization of a twisted group action on a ring as a homomorphism $G \\
rightarrow \\mathfrak{Rings} $ and its lax and strong covariance rings. \n
We also provide few examples of strong covariance rings for some morphisms
$(\\mathbb{N}\,+) \\rightarrow \\mathfrak{Rings}$. The main idea is const
ructing a directed graph from the given morphism. The Leavitt path algebra
of such directed graph is closely related with the strong covariance ring
.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Boris Bilich (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211027T081500Z
DTEND;VALUE=DATE-TIME:20211027T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/23
DESCRIPTION:Title: Noncommutative holomorphic functional calculus for double coverings
\nby Boris Bilich (Universität Göttingen) as part of Göttingen Semi
nar Noncommutative Geometry\n\n\nAbstract\nLet $T$ be a bounded operator o
n a Banach space $X$. Let $U$ be a neighborhood of the spectrum of $T$. Th
e classical holomorphic functional calculus theorem asserts that there is
a unique continuous algebra homomorphism from the algebra of holomorphic f
unctions $\\mathcal{O}(U)$ to the algebra of bounded operators on $X$ such
that the coordinate function $z$ maps to $T$. In 1970\, Taylor extended t
his result to tuples of commuting bounded operators and holomorphic functi
ons in several variables. In later works by several authors there were att
empts to generlazie the functional calculus to non-commuting tuples of ope
rators or\, more generally\, to Banach representations of associative alge
bras. \n\nIn the talk\, I will associate a non-commutative algebra to a do
uble covering of a complex domain. One particular example of such algebra
would be a group algebra of the infinite dihedral group. Then\, I will int
roduce a structure of non-Hausdorff complex space on the primitive spectru
m of this algebra and endow it with a presheaf of noncommutative algebras\
, which will play a role of noncommutative holomorphic functions. I will d
efine a spectrum and prove the noncommutative functional calculus theorem.
I will also prove a version of the spectral mapping theorem.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey-Desmond Busche (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211103T091500Z
DTEND;VALUE=DATE-TIME:20211103T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/24
DESCRIPTION:Title: Dimension\, decomposability and nuclear C*-algebras\nby Geoffre
y-Desmond Busche (Universität Göttingen) as part of Göttingen Seminar N
oncommutative Geometry\n\n\nAbstract\nIn this talk I give a short introduc
tion to covering dimension of (separable\, metrisable) topological spaces
as defined by Hurewicz/Wallman in 1948. An important part is the Decomposa
bility Theorem\, which states that every finite open cover of an n-dimensi
onal space has an n-decomposable refinement. I give a modern proof of the
Decomposability Theorem using simplicial complices\, following a paper by
Kichberg/Winter. With respect to the same paper I compare topological cove
ring dimension to decomposition rank in C*-algebras.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Devarshi Mukherjee (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211110T091500Z
DTEND;VALUE=DATE-TIME:20211110T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/25
DESCRIPTION:Title: Local cyclic cohomology\nby Devarshi Mukherjee (Universität G
öttingen) as part of Göttingen Seminar Noncommutative Geometry\n\n\nAbst
ract\nLet $V$ be a complete discrete valuation ring with uniformiser $\\pi
$\, residue field $k = V/\\pi V$\, and fraction field $F$. In this talk\,
I will introduce an invariant of Banach $V$-algebras called local cyclic c
ohomology. This invariant is related to analytic cyclic homology for compl
ete\, bornologically torsion-free $V$-algebras. As a consequence of its de
finition and the formal properties of analytic cyclic homology\, it will b
e shown that local cyclic homology only depends on the reduction mod \\(\\
pi\\) of the original Banach \\(V\\)-algebra. Furthermore\, the invariant
we define satisfies homotopy invariance\, matricial stability and excision
. This is joint work with Joachim Cuntz and Ralf Meyer.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211117T091500Z
DTEND;VALUE=DATE-TIME:20211117T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/26
DESCRIPTION:Title: Classification of non-simple graph C*-algebras\nby Ralf Meyer (
Universität Göttingen) as part of Göttingen Seminar Noncommutative Geom
etry\n\n\nAbstract\nI speak about a project with Rasmus Bentmann that I st
arted some time ago and plan to complete in the coming weeks. The goal is
to classify graph C*-algebras\, whether simple or not\, up to isomorphism
\, using an invariant that contains the ideal structure and the K-theory o
f suitable ideals\, together with an obstruction class. The proof method
is rather elementary. We describe correspondences from a graph C*-algebra
to another C*-algebra B using projections in the stabilisation of B and c
ertain unitaries in suitable corners of the stabilisation of B. Up to hom
otopy\, we can classify these correspondences and show that a pair of maps
on a K₀- and K₁-like invariant lifts if and only if a certain homolog
ical obstruction in an Ext²-group vanishes. As of now\, the method gives
classification up to isomorphism for graph C*-algebras that are either pu
rely infinite or AF but need not be simple\, and classification up to homo
topy equivalence in general.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Taylor (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211124T091500Z
DTEND;VALUE=DATE-TIME:20211124T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/27
DESCRIPTION:Title: An analogue of the local multiplier algebra for Hilbert modules
\nby Jonathan Taylor (Universität Göttingen) as part of Göttingen Semin
ar Noncommutative Geometry\n\n\nAbstract\nGiven a C*-algebra A\, one can c
onstruct the local multiplier algebra of A into which the multiplier algeb
ras of all ideals of A embed. This allows one to define maps from other C*
-algebras into the local multiplier algebra of A by specifying how element
s may act on an ideal of A\, in particular one gains a larger suite of gen
eralised conditional expectations to work with (among other things). In th
is talk I shall show an analogous construction of the local multiplier alg
ebra for Hilbert modules\, and how one can enrich actions by Hilbert bimod
ules on A to actions on the local multiplier algebra of A. One application
of this is to enrich an inclusion of C*-algebras that is not quite Cartan
\, into a Cartan inclusion.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Becky Armstrong (Westfälische Wilhelms-Universität Münster)
DTSTART;VALUE=DATE-TIME:20211222T091500Z
DTEND;VALUE=DATE-TIME:20211222T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/28
DESCRIPTION:Title: Twisted C*-algebras of Deaconu–Renault groupoids\nby Becky Ar
mstrong (Westfälische Wilhelms-Universität Münster) as part of Götting
en Seminar Noncommutative Geometry\n\n\nAbstract\nIn 2014\, Brown\, Clark\
, Farthing\, and Sims proved that the C*-algebra of an amenable Hausdorff
étale groupoid is simple if and only if the groupoid is minimal and effec
tive. This result does not hold for the more general class of $\\textit{tw
isted}$ groupoid C*-algebras\, because\, for instance\, the irrational rot
ation algebras are simple twisted C*-algebras of non-effective groupoids.
In 2015\, Kumjian\, Pask\, and Sims used groupoid techniques to give a cha
racterisation of simplicity of twisted C*-algebras of cofinal\, row-finite
\, source-free higher-rank graphs. The groupoids involved belong to the st
rictly larger class of $\\textit{Deaconu--Renault groupoids}$. In this tal
k\, I will give a characterisation of simplicity of twisted C*-algebras of
all ($\\mathbb{Z}^k$-graded) Deaconu–Renault groupoids. (This is joint
work with Nathan Brownlowe and Aidan Sims.)\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Markus Obendrauf (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220112T091500Z
DTEND;VALUE=DATE-TIME:20220112T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/29
DESCRIPTION:Title: Classification of 2-groups using skeleta\nby Markus Obendrauf (
Universität Göttingen) as part of Göttingen Seminar Noncommutative Geom
etry\n\n\nAbstract\nCrossed modules are generalised groups\, and crossed m
odule actions are generalised group actions. Crossed modules are also the
same as strict 2-groups\, a structure arising in category theory. We use t
he tools of (bi-)category theory to classify 2-groups and crossed modules
up to equivalence.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collin Mark Joseph (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220126T091500Z
DTEND;VALUE=DATE-TIME:20220126T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/30
DESCRIPTION:Title: Geometric Construction of Hamiltonians\nby Collin Mark Joseph (
Universität Göttingen) as part of Göttingen Seminar Noncommutative Geom
etry\n\n\nAbstract\nWe compute a particular generator of the KR-theory of
the d-torus using the geometric picture of bivariant KK-theory. We use Van
Daele's K-theory to describe explicit generators for the K-theory of the
spheres.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taufik Yusof (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220209T091500Z
DTEND;VALUE=DATE-TIME:20220209T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/31
DESCRIPTION:Title: Category of modules and (classical) Morita theory\nby Taufik Yu
sof (Universität Göttingen) as part of Göttingen Seminar Noncommutative
Geometry\n\n\nAbstract\nWe revisit the classical Morita theory for unital
rings and outline the sketch of the proof. We then talk about alternative
(s) to categories of modules in the literatures\, suggesting a version of
Morita theory for the non-unital case may be made possible.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Apurva Seth (IISER Bhopal)
DTSTART;VALUE=DATE-TIME:20220119T091500Z
DTEND;VALUE=DATE-TIME:20220119T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/32
DESCRIPTION:Title: Nonstable $K$-Theory for $C^*$-Algebras\nby Apurva Seth (IISER
Bhopal) as part of Göttingen Seminar Noncommutative Geometry\n\n\nAbstrac
t\nNonstable K-theory is the study of the homotopy groups of the group of
(quasi-) unitaries of a $C^*$-algebra. We will give an overview of the the
ory and discuss a special class of $C^*$-algebras termed as $K$-stable $C^
*$-algebras along with its rational analogue. We shall give a permanence p
roperty related to $K$-stability (rational $K$-stability) concerning conti
nuous $C(X)$-algebras. We will end with a procedure to compute the rationa
l nonstable $K$-groups for AF-algebras along with some results on their $K
$-stability.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mohammed Amir (IISER Bhopal)
DTSTART;VALUE=DATE-TIME:20220202T091500Z
DTEND;VALUE=DATE-TIME:20220202T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/33
DESCRIPTION:Title: KMS states on the C*-algebra of a Fell bundle over an étale groupo
id\nby Mohammed Amir (IISER Bhopal) as part of Göttingen Seminar Nonc
ommutative Geometry\n\n\nAbstract\nFirstly\, we will discuss how to define
the full $\\textrm{C}^*$-algebra of an {\\'e}tale groupoid. After that\,
we will state Neshveyev's theorem which characterises the KMS states on th
e $\\textrm{C}^*$-algebra of an {\\'e}tale groupoid when the dynamics is g
iven by a real-valued one cocycle. Then we will discuss our generalisation
of the Neshveyev's theorem for the full $\\textrm{C}^*$-algebra of a Fell
bundle over an {\\'e}tale groupoid. And finally\, we will discuss one app
lication of our result.\n\nMeeting ID: 958 7370 6690\nPa
sscode: 295706\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Guo Chuan Thiang (Peking University\, Beijing\, China)
DTSTART;VALUE=DATE-TIME:20211208T091500Z
DTEND;VALUE=DATE-TIME:20211208T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/34
DESCRIPTION:Title: Gerbes\, topological insulators\, and quaternionic operator K-theor
y\nby Guo Chuan Thiang (Peking University\, Beijing\, China) as part o
f Göttingen Seminar Noncommutative Geometry\n\n\nAbstract\nRecently\, phy
sicists discovered that the boundary spectrum of a topological insulator i
s totally gapless in a perturbation-resistant way (mod 2). The mathematics
underlying this remarkable phenomenon involves K-theory and index theory
for operator algebras\, as well as the geometrical idea of gerbes for the
spectral interpretation. Importantly\, it takes place in the real/quaterni
onic (rather than complex) setting\, which is largely unexplored territory
potentially hiding a wealth of interesting mathematics.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211201T091500Z
DTEND;VALUE=DATE-TIME:20211201T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/35
DESCRIPTION:Title: The bicategory of groupoid correspondences\nby Ralf Meyer (Univ
ersität Göttingen) as part of Göttingen Seminar Noncommutative Geometry
\n\n\nAbstract\nWe define a bicategory with étale\, locally compact group
oids as objects and suitable correspondences\, that is\, spaces with two c
ommuting actions as arrows\; the 2-arrows are injective\, equivariant cont
inuous maps. We prove that the usual recipe for composition makes this a
bicategory\, carefully treating also non-Hausdorff groupoids and correspon
dences. We extend the groupoid C*-algebra construction to a homomorphism
from this bicategory to that of C*-algebra correspondences. We describe t
he C*-algebras of self-similar groups\, higher-rank graphs\, and discrete
Conduché fibrations in our setup.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Devarshi Mukherjee (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20211215T091500Z
DTEND;VALUE=DATE-TIME:20211215T104500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/36
DESCRIPTION:Title: Isocohomological embeddings and Hochschild homology\nby Devarsh
i Mukherjee (Universität Göttingen) as part of Göttingen Seminar Noncom
mutative Geometry\n\n\nAbstract\nWe study the interaction between various
analytification functors\,\nand a class of morphisms of rings\, called hom
otopy epimorphisms. An analytifi-\ncation functor assigns to a simplicial
commutative algebra over a ring \\(R\\)\, along\nwith a choice of Banach s
tructure on \\(R\\)\, a commutative monoid in the monoidal\nmodel category
of simplicial ind-Banach \\(R\\)-modules. We show that several\nanalytifi
cations relevant to analytic geometry - such as Tate\, overconvergent\,\nS
tein analytification\, and formal completion - are homotopy epimorphisms.\
nAnother class of examples of homotopy epimorphisms arises from Weierstras
s\,\nLaurent and rational localizations in derived analytic geometry. As a
pplications\nof this result\, we prove that Hochschild homology and the co
tangent complex\nare computable for analytic rings\, and the computation r
elies only on known\ncomputations of Hochschild homology for polynomial ri
ngs. We show that in\nvarious senses\, Hochschild homology as we define it
commutes with localizations\,\nanalytifications and completions. This is
joint work with Oren Ben-Bassat.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hao Xu (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220427T081500Z
DTEND;VALUE=DATE-TIME:20220427T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/37
DESCRIPTION:by Hao Xu (Universität Göttingen) as part of Göttingen Semi
nar Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathematisc
hes Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hao Xu (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220504T081500Z
DTEND;VALUE=DATE-TIME:20220504T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/38
DESCRIPTION:by Hao Xu (Universität Göttingen) as part of Göttingen Semi
nar Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathematisc
hes Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ali Imad Raad (KU Leuven)
DTSTART;VALUE=DATE-TIME:20220511T081500Z
DTEND;VALUE=DATE-TIME:20220511T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/39
DESCRIPTION:Title: Constructing Cartan Subalgebras in Inductive Limit C*-algebras\
nby Ali Imad Raad (KU Leuven) as part of Göttingen Seminar Noncommutative
Geometry\n\nLecture held in Sitzungssaal at Mathematisches Institut\, Gö
ttingen.\n\nAbstract\nThe concept of Cartan subalgebras in C*-algebras has
in recent years attracted attention due to its connections to geometric g
roup theory and topological dynamics\, as well as important connections to
the classification programme for C*-algebras. A relatively unexplored are
a is that of how to build Cartan subalgebras in inductive limit C*-algebra
s from Cartan subalgebras in the building blocks. In this talk\, we will e
xplore this area and give some recent existence results in certain classes
of inductive limits. We will also address the question of uniqueness of s
uch Cartan subalgebras. This talk is based on the results of my PhD\, as w
ell as recent joint work with Xin Li.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Held (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220713T081500Z
DTEND;VALUE=DATE-TIME:20220713T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/40
DESCRIPTION:Title: Bernstein's Second Adjunction Theorem\nby Jan Held (Universitä
t Göttingen) as part of Göttingen Seminar Noncommutative Geometry\n\nLec
ture held in Sitzungssaal at Mathematisches Institut\, Göttingen.\nAbstra
ct: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Celso Antunes (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220720T081500Z
DTEND;VALUE=DATE-TIME:20220720T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/41
DESCRIPTION:Title: C*-Algebras of relatively proper groupoid correspondences\nby C
elso Antunes (Universität Göttingen) as part of Göttingen Seminar Nonco
mmutative Geometry\n\nLecture held in Sitzungssaal at Mathematisches Insti
tut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Taylor (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20220601T081500Z
DTEND;VALUE=DATE-TIME:20220601T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/42
DESCRIPTION:Title: Inductive limits of noncommutative aperiodic Cartan inclusions\
nby Jonathan Taylor (Universität Göttingen) as part of Göttingen Semina
r Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathematische
s Institut\, Göttingen.\n\nAbstract\nIn 2008 Renault proved that commutat
ive Cartan pairs are given by twisted groupoid C*-algebras. In 2018 Li use
d these groupoid models to construct commutative Cartan subalgebras in ind
uctive limit C*-algebras\, where each building block C*-algebra has a comm
utative Cartan subalgebra and the connecting morphisms preserve all of the
relevant Cartan structure.\nWe generalise this result to inductive limits
where the building blocks may be noncommutative aperiodic Cartan pairs\,
showing that the inductive limit will again be a noncommutative Cartan pai
r. We give some conditions under which the inductive limit pair is also an
aperiodic inclusion. Our proof is purely C*-algebraic without passing to
groupoids\, so in particular generalises Li's proof.\nThese results are jo
int work with Ralf Meyer and Ali Imad Raad.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221027T081500Z
DTEND;VALUE=DATE-TIME:20221027T094500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/44
DESCRIPTION:Title: Representations of *-algebras by unbounded operators: Plan of the s
emester\nby Ralf Meyer (Universität Göttingen) as part of Göttingen
Seminar Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathem
atisches Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michelle Göbel (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221103T111500Z
DTEND;VALUE=DATE-TIME:20221103T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/45
DESCRIPTION:Title: Covariance algebras for actions of locally compact groups on C*- al
gebras\nby Michelle Göbel (Universität Göttingen) as part of Götti
ngen Seminar Noncommutative Geometry\n\nLecture held in Sitzungssaal at Ma
thematisches Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taufik Yusof (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221110T111500Z
DTEND;VALUE=DATE-TIME:20221110T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/46
DESCRIPTION:Title: Hilbert modules and C*-correspondences\nby Taufik Yusof (Univer
sität Göttingen) as part of Göttingen Seminar Noncommutative Geometry\n
\nLecture held in Sitzungssaal at Mathematisches Institut\, Göttingen.\nA
bstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Kern (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221124T111500Z
DTEND;VALUE=DATE-TIME:20221124T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/47
DESCRIPTION:Title: The functional calculus and its converse for regular selfadjoint
operators\nby David Kern (Universität Göttingen) as part of Götting
en Seminar Noncommutative Geometry\n\nLecture held in Sitzungssaal at Math
ematisches Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Taylor (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221222T111500Z
DTEND;VALUE=DATE-TIME:20221222T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/48
DESCRIPTION:Title: When the C*-hull is a (twisted) groupoid C*-algebra\nby Jonatha
n Taylor (Universität Göttingen) as part of Göttingen Seminar Noncommut
ative Geometry\n\nLecture held in Sitzungssaal at Mathematisches Institut\
, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20230202T111500Z
DTEND;VALUE=DATE-TIME:20230202T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/49
DESCRIPTION:Title: More examples of C*-hulls of *-algebras\nby Ralf Meyer (Univers
ität Göttingen) as part of Göttingen Seminar Noncommutative Geometry\n\
nLecture held in Sitzungssaal at Mathematisches Institut\, Göttingen.\n\n
Abstract\nI will present some more examples of C*-hulls constructed by Dow
erk\, Savchuk\, Schmüdgen using the induction theorem for C*-hulls.\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christos Kitsios (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221117T111500Z
DTEND;VALUE=DATE-TIME:20221117T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/50
DESCRIPTION:Title: Representations of *-algebras on Hilbert modules by unbounded ope
rators\nby Christos Kitsios (Universität Göttingen) as part of Gött
ingen Seminar Noncommutative Geometry\n\nLecture held in Sitzungssaal at M
athematisches Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Boris Bilich (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221201T111500Z
DTEND;VALUE=DATE-TIME:20221201T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/51
DESCRIPTION:Title: Nelson’s Theorem\nby Boris Bilich (Universität Göttingen) a
s part of Göttingen Seminar Noncommutative Geometry\n\nLecture held in Si
tzungssaal at Mathematisches Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michelle Göbel (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221208T111500Z
DTEND;VALUE=DATE-TIME:20221208T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/52
DESCRIPTION:Title: Graded algebras and induction of representations and C*-hulls\n
by Michelle Göbel (Universität Göttingen) as part of Göttingen Seminar
Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathematisches
Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michelle Göbel (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20221215T111500Z
DTEND;VALUE=DATE-TIME:20221215T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/53
DESCRIPTION:Title: Graded algebras and induction of representations and C*-hulls\n
by Michelle Göbel (Universität Göttingen) as part of Göttingen Seminar
Noncommutative Geometry\n\nLecture held in Sitzungssaal at Mathematisches
Institut\, Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20230112T111500Z
DTEND;VALUE=DATE-TIME:20230112T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/54
DESCRIPTION:Title: Some examples of C*-hulls: twisted Weyl algebras\nby Ralf Meyer
(Universität Göttingen) as part of Göttingen Seminar Noncommutative Ge
ometry\n\nLecture held in Sitzungssaal at Mathematisches Institut\, Götti
ngen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fabrizio Zanello (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20230119T111500Z
DTEND;VALUE=DATE-TIME:20230119T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/55
DESCRIPTION:Title: Host algebras for actions of topological groups\nby Fabrizio Za
nello (Universität Göttingen) as part of Göttingen Seminar Noncommutati
ve Geometry\n\nLecture held in Sitzungssaal at Mathematisches Institut\, G
öttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lennart Janshen (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20230126T111500Z
DTEND;VALUE=DATE-TIME:20230126T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/56
DESCRIPTION:Title: Host algebras for infinite-dimensional Lie groups\nby Lennart J
anshen (Universität Göttingen) as part of Göttingen Seminar Noncommutat
ive Geometry\n\nLecture held in Sitzungssaal at Mathematisches Institut\,
Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey Desmond-Busche (Universität Göttingen)
DTSTART;VALUE=DATE-TIME:20230216T111500Z
DTEND;VALUE=DATE-TIME:20230216T124500Z
DTSTAMP;VALUE=DATE-TIME:20230208T062400Z
UID:GoettingenNCG/57
DESCRIPTION:Title: The *-algebra of differential operators on a manifold\nby Geoff
rey Desmond-Busche (Universität Göttingen) as part of Göttingen Seminar
Noncommutative Geometry\n\nView-only livestream: http://streaming.math.un
i-goettingen.de\nLecture held in Sitzungssaal at Mathematisches Institut\,
Göttingen.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/GoettingenNCG/57/
URL:http://streaming.math.uni-goettingen.de
END:VEVENT
END:VCALENDAR