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BEGIN:VEVENT
SUMMARY:Ralf Meyer
DTSTART;VALUE=DATE-TIME:20200930T120000Z
DTEND;VALUE=DATE-TIME:20200930T133000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/2
DESCRIPTION:Title: Groupoid models and C*-algebras of diagrams of groupoid
correspondences\nby Ralf Meyer as part of Western Sydney\, IPM joint wor
kshop on Operator Algebras\n\n\nAbstract\nA groupoid correspondence is a g
eneralised morphism between étale groupoids. Topological graphs\, self-s
imilarities of groups\, or self-similar graphs are examples of this. Grou
poid correspondences induce C*-correspondences between groupoid C*-algebra
s\, which then give Cuntz-Pimsner algebras. The Cuntz-Pimsner algebra of
a groupoid correspondence is isomorphic to a groupoid C*-algebra of an ét
ale groupoid built from the groupoid correspondence. This gives a uniform
construction of groupoid models for many interesting C*-algebras\, such a
s graph C*-algebras of regular graphs\, Nekrashevych's C*-algebras of self
-similar groups and their generalisation by Exel and Pardo for self-simila
r graphs. If possible\, I would also like to mention work in progress to
extend this theorem to relative Cuntz-Pimsner algebras\, which would then
cover all topological graph C*-algebras.\nGroupoid correspondences form a
bicategory. This structure is already used to form the groupoid model of
a groupoid correspondence. It also allows us to define actions of monoids
or\, more generally\, of categories on groupoids by groupoid corresponden
ces. Passing to C*-algebras\, this gives a product system where the unit
fibre is a groupoid C*-algebra. If the monoid is an Ore monoid\, then the
Cuntz-Pimsner algebra of this product system is again a groupoid C*-algeb
ra of an étale groupoid\, which is defined directly from the action by gr
oupoid correspondences. For more general monoids\, the two constructions
become different\, however. We show this in a special case that is relate
d to separated graph C*-algebras and their tame versions.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aidan Sims
DTSTART;VALUE=DATE-TIME:20201001T103000Z
DTEND;VALUE=DATE-TIME:20201001T120000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/5
DESCRIPTION:Title: Reconstruction of groupoids\, and classification of Fel
l algebras\nby Aidan Sims as part of Western Sydney\, IPM joint workshop o
n Operator Algebras\n\n\nAbstract\nI will the history of reconstruction of
groupoids from pairs of operator algebras\, from Feldman and Moore’s re
sults on von Neumann algebras through Kumjian’s and then Renault’s res
ults about C*-algebras of twists\, and including some recent results about
groupoids that are not topologically principal. I will finish by outlinin
g how Kumjian’s theory leads to a Dixmier-Douady classification theorem
for Fell algebras.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer
DTSTART;VALUE=DATE-TIME:20201001T120000Z
DTEND;VALUE=DATE-TIME:20201001T133000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/6
DESCRIPTION:Title: Groupoid models and C*-algebras of diagrams of groupoid
correspondences\nby Ralf Meyer as part of Western Sydney\, IPM joint wor
kshop on Operator Algebras\n\n\nAbstract\nA groupoid correspondence is a g
eneralised morphism between étale groupoids. Topological graphs\, self-s
imilarities of groups\, or self-similar graphs are examples of this. Grou
poid correspondences induce C*-correspondences between groupoid C*-algebra
s\, which then give Cuntz-Pimsner algebras. The Cuntz-Pimsner algebra of
a groupoid correspondence is isomorphic to a groupoid C*-algebra of an ét
ale groupoid built from the groupoid correspondence. This gives a uniform
construction of groupoid models for many interesting C*-algebras\, such a
s graph C*-algebras of regular graphs\, Nekrashevych's C*-algebras of self
-similar groups and their generalisation by Exel and Pardo for self-simila
r graphs. If possible\, I would also like to mention work in progress to
extend this theorem to relative Cuntz-Pimsner algebras\, which would then
cover all topological graph C*-algebras.\nGroupoid correspondences form a
bicategory. This structure is already used to form the groupoid model of
a groupoid correspondence. It also allows us to define actions of monoids
or\, more generally\, of categories on groupoids by groupoid corresponden
ces. Passing to C*-algebras\, this gives a product system where the unit
fibre is a groupoid C*-algebra. If the monoid is an Ore monoid\, then the
Cuntz-Pimsner algebra of this product system is again a groupoid C*-algeb
ra of an étale groupoid\, which is defined directly from the action by gr
oupoid correspondences. For more general monoids\, the two constructions
become different\, however. We show this in a special case that is relate
d to separated graph C*-algebras and their tame versions.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dana Williams
DTSTART;VALUE=DATE-TIME:20201001T133000Z
DTEND;VALUE=DATE-TIME:20201001T150000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/7
DESCRIPTION:Title: Morita equivalence\, the equivariant Brauer group\, and
beyond\nby Dana Williams as part of Western Sydney\, IPM joint workshop o
n Operator Algebras\n\n\nAbstract\nI will give a brief survey of work on t
he equivariant Brauer group together with the necessary preliminaries as w
ell as generalizations involving groupoid C*-algebras.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabor Szabo
DTSTART;VALUE=DATE-TIME:20201001T150000Z
DTEND;VALUE=DATE-TIME:20201001T163000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/8
DESCRIPTION:Title: Dynamical criteria towards classifiable transformation
group C*-algebras\nby Gabor Szabo as part of Western Sydney\, IPM joint wo
rkshop on Operator Algebras\n\n\nAbstract\nIn this talk I will report on j
oint work with David Kerr regarding the structure and classification of ce
rtain transformation group C*-algebras. It is a general important question
when free minimal actions of amenable groups on compact spaces give rise
to crossed product C*-algebras that fall within the scope of Elliott's pro
gram. After some years of research where this had been partially settled f
or special classes of groups with methods related to noncommutative dimens
ion theory\, Kerr's notion of almost finiteness opens the door to systemat
ically study this problem for all amenable groups. I will give an overview
of these techniques and the current state-of-the-art\, culminating in our
result that asserts the classifiability of such crossed products if the u
nderlying space is finite-dimensional and the group has subexponential gro
wth.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Meyer
DTSTART;VALUE=DATE-TIME:20201002T103000Z
DTEND;VALUE=DATE-TIME:20201002T120000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/9
DESCRIPTION:Title: Groupoid models and C*-algebras of diagrams of groupoid
correspondences\nby Ralf Meyer as part of Western Sydney\, IPM joint wor
kshop on Operator Algebras\n\n\nAbstract\nA groupoid correspondence is a g
eneralised morphism between étale groupoids. Topological graphs\, self-s
imilarities of groups\, or self-similar graphs are examples of this. Grou
poid correspondences induce C*-correspondences between groupoid C*-algebra
s\, which then give Cuntz-Pimsner algebras. The Cuntz-Pimsner algebra of
a groupoid correspondence is isomorphic to a groupoid C*-algebra of an ét
ale groupoid built from the groupoid correspondence. This gives a uniform
construction of groupoid models for many interesting C*-algebras\, such a
s graph C*-algebras of regular graphs\, Nekrashevych's C*-algebras of self
-similar groups and their generalisation by Exel and Pardo for self-simila
r graphs. If possible\, I would also like to mention work in progress to
extend this theorem to relative Cuntz-Pimsner algebras\, which would then
cover all topological graph C*-algebras.\nGroupoid correspondences form a
bicategory. This structure is already used to form the groupoid model of
a groupoid correspondence. It also allows us to define actions of monoids
or\, more generally\, of categories on groupoids by groupoid corresponden
ces. Passing to C*-algebras\, this gives a product system where the unit
fibre is a groupoid C*-algebra. If the monoid is an Ore monoid\, then the
Cuntz-Pimsner algebra of this product system is again a groupoid C*-algeb
ra of an étale groupoid\, which is defined directly from the action by gr
oupoid correspondences. For more general monoids\, the two constructions
become different\, however. We show this in a special case that is relate
d to separated graph C*-algebras and their tame versions.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alcides Buss
DTSTART;VALUE=DATE-TIME:20201002T120000Z
DTEND;VALUE=DATE-TIME:20201002T133000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/10
DESCRIPTION:Title: Amenability for actions of groups on C*-algebras\nby Al
cides Buss as part of Western Sydney\, IPM joint workshop on Operator Alge
bras\n\n\nAbstract\nIn this lecture I will explain recent developments in
the theory of amenability for actions of groups on C*-algebras and Fell bu
ndles\, based on joint works with Siegfried Echterhoff\, Rufus Willett\, F
ernando Abadie and Damián Ferraro. Our main results prove that essentiall
y all known notions of amenability are equivalent. We also extend Matsumur
a’s theorem to actions of exact locally compact groups on commutative C*
-algebras and give a counter-example for the weak containment problem for
actions on noncommutative C*-algebras.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. Christopher Phillips
DTSTART;VALUE=DATE-TIME:20201002T133000Z
DTEND;VALUE=DATE-TIME:20201002T150000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/11
DESCRIPTION:Title: Crossed products by automorphisms of C(X\,D)\nby N. Chr
istopher Phillips as part of Western Sydney\, IPM joint workshop on Operat
or Algebras\n\n\nAbstract\nWe consider crossed products of\nthe form $C^*
\\bigl( {\\mathbb{Z}}\, \\\, C (X\, D)\, \\\, \\alpha \\bigr)$\nin which $
D$ is simple\, $X$ is compact metrizable\,\n$\\alpha$ induces a minimal ho
meomorphism $h \\colon X \\to X$\,\nand a mild technical assumption holds.
\nIn a number of examples inaccessible\nvia methods based on finite Rokhli
n dimension\,\neither because $D$ is not ${\\mathcal{Z}}$-stable\nor becau
se $X$ is infinite dimensional\,\nwe prove structural properties of the cr
ossed product\,\nsuch as (tracial) ${\\mathcal{Z}}$-stability\, stable ran
k one\,\nreal rank zero\, and pure infiniteness.\n\nThe method is to find
a centrally large subalgebra\nof the crossed product which is a direct lim
it of\n``recursive subhomogeneous algebras over $D$''.\nWith a better unde
rstanding of such direct limits\,\nmany more examples would become accessi
ble.\n\nThis is joint work with Dawn Archey and Julian Buck.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Kumjian
DTSTART;VALUE=DATE-TIME:20201002T150000Z
DTEND;VALUE=DATE-TIME:20201002T163000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/12
DESCRIPTION:Title: Pushouts of groupoid extensions by abelian group bundle
s\nby Alex Kumjian as part of Western Sydney\, IPM joint workshop on Opera
tor Algebras\n\n\nAbstract\nGiven a groupoid extension of a locally compac
t Hausdorff groupoid by a bundle of abelian groups on which it acts\, we c
onstruct a pushout twist over the groupoid semidirect product of the group
oid acting on the dual of the bundle regarded as a topological space. We
then show that the C*-algebra of the original extension groupoid is isomo
rphic to the twisted groupoid associated to the pushout. We will also dis
cuss examples. This talk is based on current joint work with Marius Iones
cu\, Jean Renault\, Aidan Sims and Dana Williams.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aidan Sims
DTSTART;VALUE=DATE-TIME:20200930T103000Z
DTEND;VALUE=DATE-TIME:20200930T120000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/24
DESCRIPTION:Title: Reconstruction of groupoids\, and classification of Fel
l algebras\nby Aidan Sims as part of Western Sydney\, IPM joint workshop o
n Operator Algebras\n\n\nAbstract\nI will the history of reconstruction of
groupoids from pairs of operator algebras\, from Feldman and Moore’s re
sults on von Neumann algebras through Kumjian’s and then Renault’s res
ults about C*-algebras of twists\, and including some recent results about
groupoids that are not topologically principal. I will finish by outlinin
g how Kumjian’s theory leads to a Dixmier-Douady classification theorem
for Fell algebras.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dana Williams
DTSTART;VALUE=DATE-TIME:20200930T133000Z
DTEND;VALUE=DATE-TIME:20200930T150000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/26
DESCRIPTION:Title: Morita equivalence\, the equivariant Brauer group\, and
beyond\nby Dana Williams as part of Western Sydney\, IPM joint workshop o
n Operator Algebras\n\n\nAbstract\nI will give a brief survey of work on t
he equivariant Brauer group together with the necessary preliminaries as w
ell as generalizations involving groupoid C*-algebras.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean Renault
DTSTART;VALUE=DATE-TIME:20200930T150000Z
DTEND;VALUE=DATE-TIME:20200930T163000Z
DTSTAMP;VALUE=DATE-TIME:20201029T104639Z
UID:WSIPM/27
DESCRIPTION:Title: KMS states and groupoid C*-algebras\nby Jean Renault as
part of Western Sydney\, IPM joint workshop on Operator Algebras\n\n\nAbs
tract\nI will illustrate the use of groupoids in the study of KMS states a
nd weights on C*-algebras. The KMS condition\, which was introduced in qua
ntum statistical mechanics to characterize equilibrium states\, plays a cr
ucial role in the theory of von Neumann algebras. The study of KMS states
and their phase transitions on specific C*-algebras\, in particular graph
algebras\, is an active field of research where the groupoid techniques ar
e well suited.\n
END:VEVENT
END:VCALENDAR