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BEGIN:VEVENT
SUMMARY:Mehrdad Kalantar (University of Houston\, USA)
DTSTART:20201109T150000Z
DTEND:20201109T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/1/">Furs
 tenberg boundary of a discrete quantum group</a>\nby Mehrdad Kalantar (Uni
 versity of Houston\, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbs
 tract\nThe notion of topological boundary actions has recently found strik
 ing applications in the study of operator algebras associated to discrete 
 groups. We will discuss the analogue concept for discrete quantum groups\,
  show that in this generalization there still always exists a maximal boun
 dary action - the so-called Furstenberg boundary. We discuss applications 
 in problems of C*-simplicity and uniqueness of the Haar state of the dual.
 \n\nThis is joint work with Pawel Kasprzak\, Adam Skalski and Roland Vergn
 ioux.\n
LOCATION:https://researchseminars.org/talk/QGS/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuki Arano (Kyoto University\, Japan)
DTSTART:20201116T150000Z
DTEND:20201116T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/2/">On t
 he Baum-Connes conjecture for discrete quantum groups with torsion and the
  quantum Rosenberg Conjecture</a>\nby Yuki Arano (Kyoto University\, Japan
 ) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nWe give a decompo
 sition of the equivariant Kasparov category for a discrete quantum group w
 ith torsions. This formulates the Baum-Connes assembly map for general dis
 crete quantum groups possibly with torsion. As an application\, we show th
 at the group C*-algebra of a discrete quantum group in a certain class sat
 isfies the UCT.\n
LOCATION:https://researchseminars.org/talk/QGS/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kenny De Commer (Vrije Universiteit Brussel\, Belgium)
DTSTART:20201123T150000Z
DTEND:20201123T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/3/">A qu
 antization of Sylvester's law of inertia</a>\nby Kenny De Commer (Vrije Un
 iversiteit Brussel\, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\
 nAbstract\nSylvester's law of inertia states that two self-adjoint matrice
 s A and B are related as $A = X^*BX$ for some invertible complex matrix $X
 $ if and only if $A$ and $B$ have the same signature $(N_+\,N_-\,N_0)$\, i
 .e. the same number of positive\, negative and zero eigenvalues. In this t
 alk\, we will discuss a quantized version of this law: we consider the ref
 lection equation *-algebra (REA)\, which is a quantization of the *-algebr
 a of polynomial functions on self-adjoint matrices\, together with a natur
 al adjoint action by quantum $GL(N\,\\mathbb{C})$. We then show that to ea
 ch irreducible bounded *-representation of the REA can be associated an ex
 tended signature $(N_+\,N_-\,N_0\,[r])$ with $[r]$ in $\\mathbb{R}/\\mathb
 b{Z}$\, and we will explain in what way this is a complete invariant of th
 e orbits under the action by quantum $GL(N\,\\mathbb{C})$. This is part of
  a work in progress jointly with Stephen Moore.\n
LOCATION:https://researchseminars.org/talk/QGS/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivo Dell'Ambrogio (Université de Lille\, France)
DTSTART:20201130T150000Z
DTEND:20201130T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/4/">The 
 spectrum of equivariant Kasparov theory for cyclic groups of prime order</
 a>\nby Ivo Dell'Ambrogio (Université de Lille\, France) as part of Quantu
 m Groups Seminar [QGS]\n\n\nAbstract\nIn 2006\, Ralf Meyer and Ryszard Nes
 t proved that the G-equivariant Kasparov category of a locally compact gro
 up G carries the structure of a tensor-triangulated category. This structu
 re conveniently handles the usual homological algebra\, bootstrap construc
 tions and assembly maps involved in many KK-theoretical calculations\, e.g
 . in connection with the Baum-Connes conjecture.  As with any tensor trian
 gulated category\, we can also associate to the G-equivariant Kasparov cat
 egory its spectrum in the sense of Paul Balmer. This is a topological spac
 e (similar to the Zariski spectrum of a commutative ring) which allows us\
 , as it were\, to re-inject some genuinely geometric ideas in non-commutat
 ive geometry. It turns out that the spectrum contains enough information t
 o prove the Baum-Connes conjecture for G\, hence we should expect the ques
 tion of its computation to be very hard.  In this talk\, after discussing 
 such preliminaries and motivation\, I will present joint work with Ralf Me
 yer providing the state of the art on this subject. Although more general 
 partial results are known\, a complete answer is only known so far for fin
 ite groups of prime order and for algebras in the bootstrap category.\n
LOCATION:https://researchseminars.org/talk/QGS/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martijn Caspers (TU Delft\, Netherlands)
DTSTART:20201207T150000Z
DTEND:20201207T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/5/">Ries
 z transforms on compact quantum groups and strong solidity</a>\nby Martijn
  Caspers (TU Delft\, Netherlands) as part of Quantum Groups Seminar [QGS]\
 n\n\nAbstract\nThe Riesz transform is one of the most important and classi
 cal examples of a Fourier multiplier on the real numbers. It may be descri
 bed as the operator $\\nabla_j \\Delta^{-1/2}$ where $\\nabla_j = d/dx_j$ 
 is the derivative and $\\Delta$ is the Laplace operator. In a more general
  context the Riesz transform may always be defined for any diffusion semig
 roup on the reals. In case the generator of this semi-group is the Laplace
  operator the classical Riesz transform is retrieved. In quantum probabili
 ty the quantum Markov semi-groups play the role of the diffusion semi-grou
 ps and again a suitable notion of Riesz transform can be described.\n\nWe 
 show that the Riesz transform may be used to prove rigidity properties of 
 von Neumann algebras. We focus in particular on examples from compact quan
 tum groups. Using these tools we show that a class of quantum groups admit
 s rigidity properties. The class has the following properties:\n\n(1) $\\t
 ext{SU}_q(2)$ is contained in it.\n\n(2) The class is stable under monoida
 l equivalence\, free products\, dual quantum subgroups and wreath products
  with $S^+_N$.\n\nThe rigidity properties include the Akemann-Ostrand prop
 erty and strong solidity. Part of this talk is based on joint work with Ma
 teusz Wasilewski and Yusuke Isono.\n
LOCATION:https://researchseminars.org/talk/QGS/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Kyed (University of Southern Denmark\, Denmark)
DTSTART:20201214T150000Z
DTEND:20201214T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/6
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/6/">Dyna
 mics of compact quantum metric spaces</a>\nby David Kyed (University of So
 uthern Denmark\, Denmark) as part of Quantum Groups Seminar [QGS]\n\n\nAbs
 tract\nThe classical Gelfand correspondence justifies the slogan that  C*-
 algebras are to be thought of as "non-commutative Hausdorff spaces"\, and 
  Rieffel's theory of compact quantum metric spaces provides\, in the same 
 vein\, a non-commutative counterpart to the theory of compact metric space
 s. The aim of my talk is to introduce the basics of this theory\, and expl
 ain some new results on dynamical systems of compact quantum metric spaces
 .   If time permits\, I will also touch upon another recent result\,  whic
 h shows  how quantized intervals approximate a classical interval in the q
 uantum version of the Gromov-Hausdorff distance. This is based on joint wo
 rks with Jens Kaad and Thomas Gotfredsen.\n
LOCATION:https://researchseminars.org/talk/QGS/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Penneys (The Ohio State University\, USA)
DTSTART:20210111T150000Z
DTEND:20210111T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/7
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/7/">Disc
 rete subfactors\, realization of algebra objects\, and Q-system completion
 </a>\nby David Penneys (The Ohio State University\, USA) as part of Quantu
 m Groups Seminar [QGS]\n\n\nAbstract\nIn recent decades\, we have seen tha
 t quantum symmetries of quantum\nmathematical objects\, like non-commutati
 ve spaces and quantum field\ntheories\, are best described by quantum grou
 ps\, subfactors\, and\nunitary tensor categories. Subfactor classification
  has led to\ndiscovery of interesting "exotic" quantum symmetries and to i
 mportant\nconstructions for unitary tensor categories. For example\, Q-sys
 tems\n(special C* Frobnius algebra objects) were introduced by Longo to\nc
 haracterize the canonical endomorphism for type III subfactors\, which\nis
  the analog of Jones' basic construction for type $II_1$ and Kosaki's\nver
 sion for type III. We will use this perspective to discuss some\nsubfactor
  results which go beyond small index classification\, making\nconnections 
 to quantum groups along the way. We'll then discuss a\nversion of a unitar
 y higher idempotent completion for C*/W*\n2-categories based on Gaiotto-Jo
 hnson-Freyd's theory of condensations\nin higher categories.\n
LOCATION:https://researchseminars.org/talk/QGS/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julien Bichon (Université Clermont Auvergne\, France)
DTSTART:20210118T150000Z
DTEND:20210118T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/8
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/8/">Abou
 t the monoidal invariance of cohomological dimension of Hopf algebras</a>\
 nby Julien Bichon (Université Clermont Auvergne\, France) as part of Quan
 tum Groups Seminar [QGS]\n\n\nAbstract\nI will discuss the question whethe
 r Hopf algebras having monoidally equivalent category of comodules have th
 e same cohomological dimension\, and I will present a new positive answer.
 \n
LOCATION:https://researchseminars.org/talk/QGS/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christian Voigt (University of Glasgow\, UK)
DTSTART:20210125T150000Z
DTEND:20210125T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/9
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/9/">Quan
 tum Cuntz-Krieger algebras</a>\nby Christian Voigt (University of Glasgow\
 , UK) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nThe notion of
  a quantum graph\, a concept going back to work of Erdos-Katavolos-Shulman
  and Weaver\, provides a noncommutative generalisation of finite graphs. Q
 uantum graphs play an intriguing role in the analysis of quantum symmetrie
 s of graphs via monoidal equivalences\, and\nnaturally appear also in quan
 tum information theory.\n\nIn this talk\, I will discuss the construction 
 of certain C*-algebras associated with directed quantum graphs\, in analog
 y to the definition of Cuntz-Krieger algebras\, and illustrate this with s
 ome examples. (Joint work with M. Brannan\, K. Eifler\, M. Weber.)\n
LOCATION:https://researchseminars.org/talk/QGS/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amaury Freslon (Université Paris-Saclay\, France)
DTSTART:20210215T150000Z
DTEND:20210215T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/10
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/10/">How
  to (badly) quantum shuffle cards</a>\nby Amaury Freslon (Université Pari
 s-Saclay\, France) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\n
 Card shuffles can be thought of as random walks on the symmetric group\, a
 nd the study of these random walks has been a subject of interest to proba
 bilists for more than forty years. Even for one of the simplest examples\,
  the random transposition walk\, precise results concerning the convergenc
 e to equilibrium were only very recently obtained. After briefly describin
 g that setting\, I will report on a joint work with L. Teyssier and S. Wan
 g where we study an analogue of the random transposition walk on the quant
 um symmetric group\, therefore a kind of "quantum card shuffle". In partic
 ular\, we obtain a similar asymptotic description of the convergence to eq
 uilibrium\, called the "limit profile"\, involving the free Poisson distri
 bution while the classical case involved the usual Poisson distribution.\n
LOCATION:https://researchseminars.org/talk/QGS/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Nakano (University of Georgia\, USA)
DTSTART:20210222T150000Z
DTEND:20210222T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/11
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/11/">Non
 commutative Tensor Triangular Geometry</a>\nby Daniel Nakano (University o
 f Georgia\, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nIn
  this talk\, I will show how to develop a general noncommutative version o
 f Balmer's tensor triangular geometry that is applicable to arbitrary mono
 idal triangulated categories (M$\\Delta$C). Insights from noncommutative r
 ing theory is used to obtain a framework for prime\, semiprime\, and compl
 etely prime (thick) ideals of an M$\\Delta$C\, $\\mathbf K $\, and then to
  associate to $\\mathbf K$ a topological space --the Balmer spectrum $\\te
 xt{Spc }{\\mathbf K}$.\n\nWe develop a general framework for (noncommutati
 ve) support data\, coming in three different flavors\, and show that $\\te
 xt{Spc }{\\mathbf K}$ is a universal terminal object for the first two not
 ions (support and weak support). The first two types of support data are t
 hen used in a theorem that gives a method for the explicit classification 
 of the thick (two-sided) ideals and the Balmer spectrum of an M$\\Delta$C.
  The third type (quasi support) is used in another theorem that provides a
  method for the explicit classification of the thick right ideals of $\\ma
 thbf K$\, which in turn can be applied to classify the thick two-sided ide
 als and $\\text{Spc }{\\mathbf K}$.\n\nIf time permits applications will b
 e given for quantum groups and non-cocommutative finite-dimensional Hopf a
 lgebras studied by Benson and Witherspoon.\n\nThis is joint and ongoing wo
 rk with Milen Yakimov and Kent Vashaw\n
LOCATION:https://researchseminars.org/talk/QGS/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnaud Brothier (University of New South Wales\, Australia)
DTSTART:20210308T080000Z
DTEND:20210308T090000Z
DTSTAMP:20260422T145751Z
UID:QGS/13
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/13/">Fro
 m subfactors to actions of the Thompson group</a>\nby Arnaud Brothier (Uni
 versity of New South Wales\, Australia) as part of Quantum Groups Seminar 
 [QGS]\n\n\nAbstract\nIn his quest in constructing conformal field theories
  from subfactors Vaughan Jones found an efficient machine to construct act
 ions of groups like the Thompson groups. I will briefly explain the story 
 of this discovery. I will then present a general overview of those Jones a
 ctions providing explicit examples. Some of the results presented come fro
 m joint works with Vaughan Jones and with Valeriano Aiello and Roberto Con
 ti.\n
LOCATION:https://researchseminars.org/talk/QGS/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Réamonn Ó Buachalla (Charles University\, Czech Republic)
DTSTART:20210315T150000Z
DTEND:20210315T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/14
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/14/">Qua
 ntum Root Vectors and a Dolbeault Double Complex for the A-Series Quantum 
 Flag Manifolds</a>\nby Réamonn Ó Buachalla (Charles University\, Czech R
 epublic) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nIn the 200
 0s a series of seminal papers by Heckenberger and Kolb introduced an essen
 tially unique covariant $q$-deformed de Rham complex for the irreducible q
 uantum flag manifolds. In the years since\, it has become increasingly cle
 ar that these differential graded algebras have a central role to play in 
 the noncommutative geometry of Drinfeld-Jimbo quantum groups. Until now\, 
 however\, the question of how to extend Heckenberger and Kolb's constructi
 on beyond the irreducible case has not been examined. Here we address this
  question for the $A$-series Drinfeld-Jimbo quantum groups $U_q(\\frak{sl}
 _{n+1})$\, and show that for precisely two reduced decompositions of the l
 ongest element of the Weyl group\, Lusztig's associated space of quantum r
 oot vectors gives a quantum tangent space for the full quantum flag manifo
 ld $\\mathcal{O}_q(F_{n+1})$ with associated differential graded algebra o
 f classical dimension. Moreover\, its restriction to the quantum Grassmann
 ians recovers the $q$-deformed complex of Heckenberger and Kolb\, giving a
  conceptual explanation for their origin. Time permitting\, we will discus
 s the noncommutative Kähler geometry of thesespaces and the proposed exte
 nsion of the root space construction to the other series. (Joint work with
  P. Somberg)\n
LOCATION:https://researchseminars.org/talk/QGS/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Appel (University of Parma\, Italy)
DTSTART:20210322T150000Z
DTEND:20210322T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/15
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/15/">Qua
 ntum affine algebras and spectral k-matrices</a>\nby Andrea Appel (Univers
 ity of Parma\, Italy) as part of Quantum Groups Seminar [QGS]\n\n\nAbstrac
 t\nThe Yang-Baxter equation (YBE) and the reflection equation (RE) are two
  fundamental\nsymmetries in mathematics arising from particles moving alon
 g a line or a half-line.\nThe quest for constant solutions of YBE (R-matri
 ces) is at the very origin of the Drinfeld-Jimbo\nquantum groups and their
  universal R-matrix. Similarly\, constant solutions of RE (k-matrices)\nna
 turally appear in the context of quantum symmetric pairs (QSP).\n\nIn join
 t work with Bart Vlaar\, we construct a discrete family of universal k-mat
 rices associated to\nan arbitrary quantum symmetric Kac-Moody pair as oper
 ators on category O integrable\nrepresentations. This generalises previous
  results by Balagovic-Kolb and Bao-Wang valid\nfor finite-type QSP. In thi
 s talk\, I will explain how\, in affine type\, this construction gives ris
 e to\nparameter-dependent operators (spectral k-matrices) on finite-dimens
 ional representations of\nquantum loop algebras solving the same RE introd
 uced by Cherednik and Sklyanin in the 1980s\nin the context of quantum int
 egrability near a boundary.\n
LOCATION:https://researchseminars.org/talk/QGS/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Debashish Goswami (Indian Statistical Institute\, India)
DTSTART:20210329T140000Z
DTEND:20210329T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/16
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/16/">Qua
 ntum Galois Group of Subfactors</a>\nby Debashish Goswami (Indian Statisti
 cal Institute\, India) as part of Quantum Groups Seminar [QGS]\n\n\nAbstra
 ct\n(joint work with Suvrajit Bhattacharjee and Alex Chirvasitu) \n\nIn th
 is talk\, I prove the existence of a universal (terminal) object in a numb
 er of categories of Hopf algebras acting on a given subfactor $N \\subset 
 M$ (finite index\, type $\\text{II}_1$) such that $N$ is in the fixed poin
 t subalgebra of the action. These universal Hopf algebras can be interpret
 ed as a quantum group version of Galois group of the subfactor. We compute
  such universal quantum groups for certain class of subfactors\, notably t
 hose coming from outer actions of finite dimensional Hopf $\\ast$ algebras
 .\n
LOCATION:https://researchseminars.org/talk/QGS/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Reutter (Max Planck Institute for Mathematics\, Germany)
DTSTART:20210412T140000Z
DTEND:20210412T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/17
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/17/">On 
 fusion 2-categories</a>\nby David Reutter (Max Planck Institute for Mathem
 atics\, Germany) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nI 
 will revisit and categorify concepts from the theory of fusion categories 
 — including idempotent completeness and semi-simplicity\, ultimately lea
 ding to a notion of `fusion 2-category’. I will highlight structural sim
 ilarities and differences between fusion 1- and 2-categories and discuss s
 everal concrete examples. If time permits\, I will discuss the role of fus
 ion 2-categories as a natural building block for 4-dimensional topological
  field theories.\n
LOCATION:https://researchseminars.org/talk/QGS/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandru Chirvasitu (University at Buffalo\, USA)
DTSTART:20210419T140000Z
DTEND:20210419T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/18
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/18/">Non
 -commutative balls and quantum group structures</a>\nby Alexandru Chirvasi
 tu (University at Buffalo\, USA) as part of Quantum Groups Seminar [QGS]\n
 \n\nAbstract\nThe Toeplitz algebra attached to the unit disk is the univer
 sal C∗-algebra generated by an\nisometry\, and is a non-commutative anal
 ogue of the unit disk. Similarly\, one can attach algebras to non-commutat
 ive counterparts of non-compact Hermitian symmetric spaces. I will discuss
  results to the effect that such quantum spaces cannot admit quantum group
  structures\, i.e. their attached non-commutative “function algebras” 
 do not admit reasonable Hopf algebra structures.\n\n(joint w/ Jacek Krajcz
 ok and Piotr Soltan)\n
LOCATION:https://researchseminars.org/talk/QGS/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Schapiro (UC Berkeley\, USA)
DTSTART:20210426T140000Z
DTEND:20210426T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/19
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/19/">Clu
 ster realization of spherical DAHA</a>\nby Alexander Schapiro (UC Berkeley
 \, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nSpherical s
 ubalgebra of Cherednik's double affine Hecke algebra of type A admits a po
 lynomial representation in which its generators act via elementary symmetr
 ic functions and Macdonald operators. Recognizing the elementary symmetric
  functions as eigenfunctions of quantum Toda Hamiltonians\, and applying (
 the inverse of) the Toda spectral transform\, one obtains a new representa
 tion of spherical DAHA. In this talk\, I will discuss how this new represe
 ntation gives rise to an injective homomorphism from the spherical DAHA in
 to a quantum cluster algebra in such a way that the action of the modular 
 group on the former is realized via cluster transformations.\n\nThe talk i
 s based on a joint work in progress with Philippe Di Francesco\, Rinat Ked
 em\, and Gus Schrader.\n
LOCATION:https://researchseminars.org/talk/QGS/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Corey Jones (North Carolina State University\, USA)
DTSTART:20210503T140000Z
DTEND:20210503T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/20
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/20/">Act
 ions of fusion categories on topological spaces</a>\nby Corey Jones (North
  Carolina State University\, USA) as part of Quantum Groups Seminar [QGS]\
 n\n\nAbstract\nFusion categories are algebraic objects which generalize th
 e representation categories of finite quantum groups.  We define an action
  of a (unitary) fusion category C on a compact Hausdorff space X to be a C
  module category structure on Hilb(X)\, the category of finite dimensional
  Hilbert bundles over a compact Hausdorff space X. When X is connected\, w
 e discuss obstructions to the existence of such actions and describe techn
 iques for building examples.\n
LOCATION:https://researchseminars.org/talk/QGS/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rémi Boutonnet (Institut de Mathématiques de Bordeaux\, France)
DTSTART:20210510T140000Z
DTEND:20210510T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/21
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/21/">Non
 -commutative ergodic theory of semi-simple lattices</a>\nby Rémi Boutonne
 t (Institut de Mathématiques de Bordeaux\, France) as part of Quantum Gro
 ups Seminar [QGS]\n\n\nAbstract\nIn the late 90's\, Nevo and Zimmer wrote 
 a series of papers describing the general structure of stationnary actions
  of higher rank semi-simple Lie groups G on probability spaces. With Cyril
  Houdayer we extended this result in two ways: first we upgraded it to act
 ions on non-commutative spaces (von Neumann algebras)\, and we also manage
 d to study actions of lattices in G. I will explain this non-commutative e
 rgodic theorem and the main ingredients of proof\, and give striking conse
 quences on the unitary representations of these lattices and their charact
 ers.\n
LOCATION:https://researchseminars.org/talk/QGS/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laura Mančiska (University of Copenhagen\, Denmark)
DTSTART:20210524T140000Z
DTEND:20210524T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/23
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/23/">Qua
 ntum groups and nonlocal games</a>\nby Laura Mančiska (University of Cope
 nhagen\, Denmark) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nI
 n this talk I will explain how quantum groups arise in quantum information
  theory via a class of graph based nonlocal games. Our point of departure 
 will be an interactive protocol (nonlocal game) where two provers try to c
 onvince a verifier that two graphs are isomorphic. Allowing provers to tak
 e advantage of shared quantum mechanical resources will then allow us to d
 efine quantum isomorphism of graphs as the ability of quantum players to w
 in the corresponding game with certainty. We will see that quantum isomorp
 hism can be naturally reformulated in the language of quantum groups.\n
LOCATION:https://researchseminars.org/talk/QGS/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Paolo Saracco (Université Libre de Bruxelles\, Belgium)
DTSTART:20210531T140000Z
DTEND:20210531T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/30
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/30/">Glo
 balization for Geometric Partial Comodules</a>\nby Paolo Saracco (Universi
 té Libre de Bruxelles\, Belgium) as part of Quantum Groups Seminar [QGS]\
 n\n\nAbstract\n(based on a joint work [2] with Joost Vercruysse)\n\nThe st
 udy of partial symmetries (partial actions and coactions\, partial represe
 ntations and corepresentations\, partial comodule algebras) is a relativel
 y recent field in continuous expansion and\, therein\, one of the relevant
  questions is the existence and uniqueness of a so-called globalization (o
 r enveloping action). \nFor instance\, in the framework of partial actions
  of groups any global action of a group $G$ on a set induces a partial act
 ion of the group on any subset by restriction. The idea behind the concept
  of globalization of a given partial action is to find a (universal) $G$-s
 et such that the initial partial action can be realized as the restriction
  of this global one.\n\nWe propose here a categorical approach to partial 
 symmetries and the globalization question\, explaining several of the exis
 ting results and\, at the same time\, providing a procedure to construct g
 lobalizations in concrete contexts of interest. Our approach relies on the
  notion of geometric partial comodules\, recently introduced by Hu and Ver
 cruysse [1] in order to describe partial actions of algebraic groups from 
 a Hopf-algebraic point of view.\n\nUnlike classical partial actions\, whic
 h exist only for (topological) groups and Hopf algebras\, geometric partia
 l comodules can be defined over any coalgebra in a monoidal category with 
 pullbacks and they allow to describe phenomena that are out of the reach o
 f the theory of partial (co)actions\, even in the Hopf algebra framework. 
 At the same time\, geometric partial comodules allow to approach in a unif
 ied way partial actions of groups on sets\, partial coactions of Hopf alge
 bras on algebras and partial (co)actions of Hopf algebras on vector spaces
 .\nThus\, the question of studying the existence (and uniqueness) of globa
 lization for geometric partial comodules naturally arises as a unifying wa
 y to address the issue.\n\nReferences:\n\n[1] J. Hu\, J.Vercruysse - Geome
 trically partial actions. Trans. Amer. Math. Soc. 373 (2020)\, no. 6\, 408
 5-4143.\n\n[2] P. Saracco\, J. Vercruysse - Globalization for geometric pa
 rtial comodules. Part I: general theory. Preprint (2021).\n
LOCATION:https://researchseminars.org/talk/QGS/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aryan Ghobadi (Queen Mary University of London\, UK)
DTSTART:20210607T140000Z
DTEND:20210607T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/31
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/31/">Hop
 f algebras in SupLat and set-theoretical YBE solutions</a>\nby Aryan Ghoba
 di (Queen Mary University of London\, UK) as part of Quantum Groups Semina
 r [QGS]\n\n\nAbstract\nSkew braces have recently attracted attention as a 
 method to study set-theoretical solutions of the Yang-Baxter equation. In 
 this talk\, we will present a new approach for studying these solutions\, 
 by looking at Hopf algebras in the category of complete lattices and join-
 preserving morphisms\, denoted by SupLat. Any Hopf algebra\, H in SupLat\,
  has a corresponding group\, R(H)\, which we call its remnant and a co-qua
 sitriangular structure on H induces a brading operator on R(H)\, which ind
 uces a skew brace structure on R(H). From this correspondence\, we will re
 cover several aspects of the theory of skew braces. In particular\, we wil
 l construct the universal skew brace of a set-theoretical YBE solution\, a
 s the remnant of an FRT-type reconstruction in SupLat.\n
LOCATION:https://researchseminars.org/talk/QGS/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Satyajit Guin (Indian Institute of Technology Kanpur\, India)
DTSTART:20210614T140000Z
DTEND:20210614T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/32
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/32/">Equ
 ivariant spectral triple for the compact quantum group $U_q(2)$ for comple
 x deformation parameters</a>\nby Satyajit Guin (Indian Institute of Techno
 logy Kanpur\, India) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract
 \nLet $q=|q|e^{i\\pi\\theta}$ be a nonzero complex number such that $|q|\\
 neq 1$\, and consider the compact quantum group $U_q(2)$. In this talk\, w
 e discuss a complete list of inequivalent irreducible representations of $
 U_q(2)$ and its Peter-Weyl decomposition. Then\, for $\\theta\\notin\\math
 bb{Q}\\setminus\\{0\,1\\}$\, we discuss the $K$-theory of the underlying $
 C^*$-algebra $C(U_q(2))$\, and a spectral triple which is equivariant unde
 r its own comultiplication action. The spectral triple obtained here is ev
 en\, $4^+$-summable\, non-degenerate\, and the Dirac operator acts on two 
 copies of the $L^2$-space of $U_q(2)$. The Chern character of the associat
 ed Fredholm module is nontrivial.\n
LOCATION:https://researchseminars.org/talk/QGS/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Moritz Weber (Saarland University\, Germany)
DTSTART:20210621T140000Z
DTEND:20210621T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/33
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/33/">Ort
 hogonal vs unitary in the case of "easy" quantum groups</a>\nby Moritz Web
 er (Saarland University\, Germany) as part of Quantum Groups Seminar [QGS]
 \n\n\nAbstract\nWe consider quantum subgroups of Wang’s free orthogonal 
 quantum group on the one hand and of his free unitary quantum group on the
  other. In the first case\, the generators of the underlying C*-algebras a
 re selfadjoint which is dropped in the latter case. We compare these two c
 ases along the lines of so called "easy" quantum groups and we observe tha
 t the step from the orthogonal to the unitary case is huge. This is a surv
 ey talk on the landscape of "easy" quantum groups with a particular emphas
 is on the differences between the orthogonal and the unitary case.\n
LOCATION:https://researchseminars.org/talk/QGS/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shintaro Nishikawa (University of Münster\, Germany)
DTSTART:20210920T140000Z
DTEND:20210920T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/34
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/34/">Cro
 ssed products of representable localization algebras</a>\nby Shintaro Nish
 ikawa (University of Münster\, Germany) as part of Quantum Groups Seminar
  [QGS]\n\n\nAbstract\nLet X be a locally compact\, Hausdorff space. The re
 presentable localization algebra for X was introduced and studied by Wille
 tt and Yu. The K-theory of the algebra serves as the representable K-homol
 ogy of the space X.\n\nNow let G be a second countable\, locally compact g
 roup and suppose that X is a proper G-space. It turns out that the K-theor
 y of the crossed product by G of the representable localization algebra fo
 r X serves as the representable G-equivariant K-homology of the proper G-s
 pace X.\n\nThe goal of this talk is to describe these facts and roles of t
 he representable localization algebras in the study of the Baum--Connes co
 njecture.\n
LOCATION:https://researchseminars.org/talk/QGS/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dominic Verdon (University of Bristol\, UK)
DTSTART:20210927T140000Z
DTEND:20210927T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/35
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/35/">A c
 ovariant Stinespring theorem</a>\nby Dominic Verdon (University of Bristol
 \, UK) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nWe will intr
 oduce a finite-dimensional covariant Stinespring theorem for compact quant
 um groups. Let G be a compact quantum group\, and let T:= Rep(G) be the ri
 gid C*-tensor category of finite-dimensional continuous unitary representa
 tions of G. Let Mod(T) be the rigid C*-2-category of cofinite semisimple f
 initely decomposable T-module categories. We show that finite-dimensional 
 G-C*-algebras (a.k.a C*-dynamical systems) can be identified with equivale
 nce classes of 1-morphisms out of the object T in Mod(T). For 1-morphisms 
 X: T -> M1\, Y: T -> M2\, we show that covariant channels between the corr
 esponding G-C*-algebras can be 'dilated' to isometries t: X -> Y \\otimes 
 E\, where E: M2 -> M1 is some 'environment' 1-morphism. Dilations are uniq
 ue up to partial isometry on the environment\; in particular\, the dilatio
 n minimising the quantum dimension of the environment is unique up to a un
 itary. When G is a compact group this implies and generalises previous cov
 ariant Stinespring-type theorems.\n\nWe will also discuss some results rel
 ating to rigid C*-2-categories\, including that any connected semisimple r
 igid C*-2-category is equivalent to Mod(T) for some rigid C*-tensor catego
 ry T. (Here semisimple means not just semisimplicity of Hom-categories but
  also idempotent splitting for 1-morphisms\, direct sums for objects\, etc
 .)\n\nThis talk is based on the paper arXiv:2108.09872.\n
LOCATION:https://researchseminars.org/talk/QGS/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Skalski (IMPAN\, Poland)
DTSTART:20211004T140000Z
DTEND:20211004T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/36
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/36/">Gau
 ssian states and Gaussian parts of compact quantum groups</a>\nby Adam Ska
 lski (IMPAN\, Poland) as part of Quantum Groups Seminar [QGS]\n\n\nAbstrac
 t\nI will motivate and explain the notion of a Gaussian state on a compact
  quantum group G\, as introduced by Michael Schürmann. This concept leads
  to the idea of the Gaussian part of G\, understood as the smallest quantu
 m subgroup of G which supports all the Gaussian states of G. I will discus
 s properties of Gaussian states and compute Gaussian parts for several exa
 mples. This turns out to be related to quantum connectedness and certain t
 opological generation questions for quantum subgroups. The talk will be ba
 sed on joint work with Uwe Franz and Amaury Freslon.\n
LOCATION:https://researchseminars.org/talk/QGS/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julian Kranz (University of Münster\, Germany)
DTSTART:20211011T140000Z
DTEND:20211011T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/37
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/37/">Ame
 nability and weak containment for étale groupoids</a>\nby Julian Kranz (U
 niversity of Münster\, Germany) as part of Quantum Groups Seminar [QGS]\n
 \n\nAbstract\nA famous theorem of Hulanicki says that a locally compact gr
 oup is amenable if and only if its full and reduced C*-algebras coincide. 
 For groupoids\, the situation is more delicate: While amenability implies 
 equatility of the full and reduced C*-algebra\, the converse fails accordi
 ng to examples by Willett. The behavior of Willett's groupoids can be expl
 ained by their non-exactness. We show that if an étale groupoid satisfies
  a certain exactness condition\, then equality of its full and reduced C*-
 algebra is equivalent to amenability of the groupoid.\n
LOCATION:https://researchseminars.org/talk/QGS/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonas Wahl (Hausdorff Center of Mathematics\, Germany)
DTSTART:20211025T140000Z
DTEND:20211025T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/39
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/39/">An 
 introduction to diagram algebras</a>\nby Jonas Wahl (Hausdorff Center of M
 athematics\, Germany) as part of Quantum Groups Seminar [QGS]\n\n\nAbstrac
 t\nIn this talk\, I will introduce the notion of a diagram algebra and exp
 lain their connection to the representation theory of compact quantum grou
 ps. I will also describe the role that they play for loop models in statis
 tical physics as well as the correspondence between their traces and rando
 m walks on graphs.\n
LOCATION:https://researchseminars.org/talk/QGS/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Jordan (University of Edinburgh\, UK)
DTSTART:20211101T150000Z
DTEND:20211101T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/40
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/40/">Clu
 ster quantization from factorization homology</a>\nby David Jordan (Univer
 sity of Edinburgh\, UK) as part of Quantum Groups Seminar [QGS]\n\n\nAbstr
 act\nThe character variety of a manifold is its moduli space of flat G-bun
 dles. These moduli spaces and their quantizations appear in a number of pl
 aces in mathematics\, representation theory\, and quantum field theory. Fa
 mously\, Fock and Goncharov showed that a certain "decorated" variant of c
 haracter varieties carries the structure of a cluster variety -- that is\,
  the moduli space contains a distinguished set of toric charts\, with comb
 inatorially defined transitions functions (called mutations). This led the
 m to a now-famous quantization of their decorated character varieties.\n\n
 In this talk I'll explain that the by-hands construction of these charts b
 y Fock and Goncharov can in fact be extracted from a more general framewor
 k called stratified factorization homology\, and I'll outline how this all
 ows us to extend the Fock-Goncharov story from surfaces to 3-manifolds.\n
LOCATION:https://researchseminars.org/talk/QGS/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Apurva Seth (Indian Institute of Science Education and Research - 
 Bhopal\, India)
DTSTART:20211108T150000Z
DTEND:20211108T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/41
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/41/">$C(
 X)$-Algebras and their K-Stability</a>\nby Apurva Seth (Indian Institute o
 f Science Education and Research - Bhopal\, India) as part of Quantum Grou
 ps Seminar [QGS]\n\n\nAbstract\nNon-stable K-theory is the study of the ho
 motopy groups of the group of (quasi-) unitaries of a $C^{*}$-algebra. We 
 will give an overview of the theory\, and discuss a special class of $C^{*
 }$-algebras\, termed as K-stable $C^{*}$-algebras along with its rational 
 analogue. We shall give a permanence property related to K-stability (rati
 onal K-stability) concerning continuous $C(X)$-algebras. We will end with 
 an application of the aforementioned result to crossed product $C^{*}$-alg
 ebras.\n
LOCATION:https://researchseminars.org/talk/QGS/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Floris Elzinga (University of Oslo\, Norway)
DTSTART:20211123T100000Z
DTEND:20211123T110000Z
DTSTAMP:20260422T145751Z
UID:QGS/43
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/43/">Str
 ongly 1-Bounded Quantum Group von Neumann Algebras</a>\nby Floris Elzinga 
 (University of Oslo\, Norway) as part of Quantum Groups Seminar [QGS]\n\n\
 nAbstract\nStrong $1$-boundedness is a property for a tracial von Neumann 
 algebra $M$ that was introduced by Jung that allows one to distinguish $M$
  from the (interpolated) free group factors. Many examples came from group
  von Neumann algebras\, such as those from certain groups having property 
 (T). For quantum group von Neumann algebras\, Brannan and Vergnioux showed
  in a landmark paper that those coming from the orthogonal free quantum gr
 oups are strongly $1$-bounded\, despite sharing many structural properties
  with the free group factors. We first review these developments\, and the
 n report on recent progress concerning permanence of strong $1$-boundednes
 s under finite index subfactors and applications to quantum automorphism g
 roups such as the quantum permutation group $S_{N^2}^+$. This last part is
  based on ongoing joint work with Brannan\, Harris\, and Yamashita.\n\nNot
 e the unusual day and time!\n
LOCATION:https://researchseminars.org/talk/QGS/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hadewijch De Clercq (Ghent University\, Belgium)
DTSTART:20211129T150000Z
DTEND:20211129T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/44
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/44/">Dyn
 amical quantum graphical calculus</a>\nby Hadewijch De Clercq (Ghent Unive
 rsity\, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nGr
 aphical calculus provides a diagrammatic framework for performing topologi
 cal computations with morphisms in strict tensor categories. The key idea 
 is to identify such morphisms with oriented diagrams labeled by their in- 
 and output objects. This was formalized by Reshetikhin and Turaev\, by con
 structing for every strict tensor category $C$ a strict tensor functor tha
 t assigns isotopy classes of $C$-colored ribbon graphs to morphisms in $C$
 . This can be applied to the tensor category of finite-dimensional represe
 ntations of a quantum group $U_q(g)$.\n\nIn this talk\, I will first outli
 ne the fundamentals of this finite-dimensional quantum graphical calculus.
  Then I will explain how it can be extended to a larger category of quantu
 m group representations\, encompassing the quantum group analog of the BGG
  category $O$. In particular\, this extended framework allows to visualize
  $U_q(g)$-intertwiners on Verma modules\, as well as morphisms depending o
 n a dynamical parameter\, such as dynamical R-matrices. Finally\, I will d
 escribe how this dynamical quantum graphical calculus can be used to obtai
 n q-difference equations for quantum spherical functions.\n\nThis talk is 
 based on joint work with Nicolai Reshetikhin (UC Berkeley) and Jasper Stok
 man (University of Amsterdam)\n
LOCATION:https://researchseminars.org/talk/QGS/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sophie Emma Mikkelsen (University of Southern Denmark\, Denmark)
DTSTART:20211213T150000Z
DTEND:20211213T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/46
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/46/">On 
 the quantum symplectic sphere</a>\nby Sophie Emma Mikkelsen (University of
  Southern Denmark\, Denmark) as part of Quantum Groups Seminar [QGS]\n\n\n
 Abstract\nThe algebra of the quantum symplectic $(4n-1)$-sphere $\\mathcal
 {O}(S_q^{4n-1})$ is defined as a subalgebra of the quantum symplectic grou
 p by Faddeev\, Reshetikhin and Takhtajan. Recently D'Andrea and Landi inve
 stigated faithfull irreducible $*$-representations of $\\mathcal{O}(S_q^{4
 n-1})$. They proved that the first $n-1$ generators of its enveloping $C^*
 $-algebra $C(S_q^{4n-1})$ are all zero. The result is a generalisation of 
 the case where $n=2$ which was shown by Mikkelsen and Szymański.\nIn this
  talk\, I will first present how $C(S_q^{4n-1})$ can be described as a gra
 ph $C^*$-algebra\, from which it follows that $C(S_q^{4n-1})$ is isomorphi
 c to the quantum $(2n+1)$-sphere by Vaksman and Soibelman. Then\, I presen
 t a candidate of a vector space basis for $\\mathcal{O}(S_q^{4n-1})$ which
  is constructed by a nontrivial application of the Diamond lemma. The conj
 ecture is supported by computer experiments for $n=1\,...\,8$.  By finding
  a vector space basis we can moreover conclude that the $n-1$ generators a
 re non-zero inside the algebra $\\mathcal{O}(S_q^{4n-1})$.\n
LOCATION:https://researchseminars.org/talk/QGS/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jeremiah McCarthy (Munster Technological University\, Ireland)
DTSTART:20220124T150000Z
DTEND:20220124T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/47
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/47/">The
  Frucht property in the quantum group setting</a>\nby Jeremiah McCarthy (M
 unster Technological University\, Ireland) as part of Quantum Groups Semin
 ar [QGS]\n\n\nAbstract\nA classical theorem of Frucht states that every fi
 nite group is the automorphism group of a finite graph. Is every quantum p
 ermutation group the quantum automorphism group of a finite graph? In this
  talk we will answer this question with the help of orbits and orbitals. T
 his talk is based on joint work with Teo Banica.\n
LOCATION:https://researchseminars.org/talk/QGS/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Benoît Collins (Kyoto University\, Japan)
DTSTART:20220131T130000Z
DTEND:20220131T140000Z
DTSTAMP:20260422T145751Z
UID:QGS/48
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/48/">A m
 etric characterization of freeness</a>\nby Benoît Collins (Kyoto Universi
 ty\, Japan) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nFreenes
 s of random variables has many characterizations\, with free cumulants\, f
 ree entropy\, Schwinger-Dyson equations\, etc. Here\, we discuss a new met
 ric characterization with the norm of the sum of generators tensored by th
 eir adjoint\, and explain the relation and applications to other problems 
 in operator algebras and von Neumann algebras. Time permitting\, we will a
 lso discuss some ingredients of the proof. This is based on joint work wit
 h Leonard Cadilhac.\n
LOCATION:https://researchseminars.org/talk/QGS/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon Schmidt (University of Copenhagen\, Denmark)
DTSTART:20220207T150000Z
DTEND:20220207T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/49
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/49/">A g
 raph with quantum symmetry and finite quantum automorphism group</a>\nby S
 imon Schmidt (University of Copenhagen\, Denmark) as part of Quantum Group
 s Seminar [QGS]\n\n\nAbstract\nThis talk concerns quantum automorphism gro
 ups of graphs\, a generalization of automorphism groups of graphs in the f
 ramework of compact matrix quantum groups. We will focus on certain colore
 d graphs constructed from linear constraint systems. In particular\, we wi
 ll give an explicit connection of the solution group of the linear constra
 int system and the quantum automorphism group of the corresponding colored
  graph. Using this connection and a decoloring procedure\, we will present
  an example of a graph with quantum symmetry and finite quantum automorphi
 sm group. This talk is based on joint work with David Roberson.\n
LOCATION:https://researchseminars.org/talk/QGS/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Haonan Zhang (Institute of Science and Technology Austria\, Austri
 a)
DTSTART:20220214T150000Z
DTEND:20220214T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/50
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/50/">Lp-
 Lq Fourier multipliers on locally compact quantum groups</a>\nby Haonan Zh
 ang (Institute of Science and Technology Austria\, Austria) as part of Qua
 ntum Groups Seminar [QGS]\n\n\nAbstract\nHörmander proved that the Fourie
 r multiplier is Lp-Lq bounded if the symbol lies in the weak Lr space\, fo
 r certain p\,q\,r. In recent years\, this result was generalized to more g
 eneral groups and quantum groups. Here we presented an extension to certai
 n locally compact quantum groups. It covers the known results and the proo
 f is simpler. It also yields a family of Lp-Fourier multipliers over compa
 ct quantum groups of Kac type. The talk is based on arXiv:2201.08346.\n
LOCATION:https://researchseminars.org/talk/QGS/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simeng Wang (Harbin Institute of Technology\, China)
DTSTART:20220221T140000Z
DTEND:20220221T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/51
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/51/">Par
 titions\, quantum group actions and rigidity</a>\nby Simeng Wang (Harbin I
 nstitute of Technology\, China) as part of Quantum Groups Seminar [QGS]\n\
 n\nAbstract\nIn this talk\, I will present a new combinatorial approach to
  the study of ergodic actions of compact quantum groups. The connection be
 tween compact quantum groups and the combinatorics of partitions goes back
  to Banica's founding work on the representation theory of free orthogonal
  quantum groups\, and was later formalized in the seminal paper of Banica 
 and Speicher under the theory of "easy quantum groups". Based on some new 
 alternative version of the Tannaka-Krein reconstruction procedure for ergo
 dic actions\, we extend Banica and Speicher's combinatorial approach to th
 e setting of ergodic actions of compact quantum groups. Our examples in pa
 rticular recovers actions on finite spaces\, on embedded homogeneous space
 s and on quotient spaces. Moreover\, we use this categorical point of view
  to study the quantum rigidity of ergodic actions on classical spaces\, an
 d show that the free quantum groups cannot act ergodically on a classical 
 connected compact space\, thereby answering a question of D. Goswami and H
 . Huang.\n\nThe talk is based on the recent preprint arXiv:2112.07506 join
 tly with Amaury Freslon and Frank Taipe.\n
LOCATION:https://researchseminars.org/talk/QGS/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Philipp Schmitt (Leibniz University Hannover\, Germany)
DTSTART:20220307T150000Z
DTEND:20220307T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/52
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/52/">Qua
 ntization of the 2-sphere</a>\nby Philipp Schmitt (Leibniz University Hann
 over\, Germany) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nThe
  quantization problem is the problem of associating non-commutative quantu
 m algebras to a classical Poisson algebra in such a way that the commutato
 r is related to the Poisson bracket. In a formal setting\, this problem an
 d its equivariant counterpart are well-understood and can always be solved
  (under a mild assumption in the equivariant case). However\, in a C*-alge
 braic setting\, there exist obstructions to equivariant quantization\, for
  example for the 2-sphere. In this talk\, we will give a brief introductio
 n to the quantization problem\, and propose a way to obtain an equivariant
  quantization of the 2-sphere in a Fréchet algebraic setting.\n
LOCATION:https://researchseminars.org/talk/QGS/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Suvrajit Bhattacharjee (Charles University\, Czech Republic)
DTSTART:20220328T140000Z
DTEND:20220328T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/55
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/55/">Bra
 ided quantum symmetries of graph C*-algebras</a>\nby Suvrajit Bhattacharje
 e (Charles University\, Czech Republic) as part of Quantum Groups Seminar 
 [QGS]\n\n\nAbstract\nA braided compact quantum group (over T) is\, roughly
  speaking\, a “compact quantum group” object in the category of T-C*-a
 lgebras equipped with a twisted monoidal structure. In this talk\, we shal
 l explain the existence of a universal braided compact quantum group actin
 g on a graph C*-algebra in the category mentioned above. Time permitting\,
  we shall sketch the proof\, constructing along the way a braided analogue
  of the free unitary quantum group. Finally\, as an example\, we shall com
 pute this universal braided compact quantum group for the Cuntz algebra.\n
LOCATION:https://researchseminars.org/talk/QGS/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ali Asadi-Vasfi (Institute of Mathematics\, Czech Academy of Scien
 ces\, Czech Republic)
DTSTART:20220404T140000Z
DTEND:20220404T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/56
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/56/">An 
 introduction to crossed products by group actions on C*-algebras</a>\nby A
 li Asadi-Vasfi (Institute of Mathematics\, Czech Academy of Sciences\, Cze
 ch Republic) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nWe giv
 e a survey of some results on crossed products by discrete group actions a
 nd discuss their basic properties. Further\, we restrict our attention to 
 finite group actions with the Rokhlin property\, approximate  representabi
 lity\, and their weakened versions. Time permitting\, we  outline some str
 ucture results for the crossed products by these classes of group actions 
 and their contributions to finite-dimensional quantum  groups.\n
LOCATION:https://researchseminars.org/talk/QGS/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pierre Bieliavsky (Université Catholique de Louvain\, Belgium)
DTSTART:20220411T140000Z
DTEND:20220411T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/57
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/57/">On 
 the differential geometry of Lie groups of Fröbenius type</a>\nby Pierre 
 Bieliavsky (Université Catholique de Louvain\, Belgium) as part of Quantu
 m Groups Seminar [QGS]\n\n\nAbstract\nThe talk will be based on the papers
 .\n\n(1) In the first one\, joint with V. Gayral (Memoirs AMS 2015)\, we c
 onstruct universal deformation formulae\nfor actions on topological algebr
 as (C* or Fréchet) of the Lie groups which carries a negatively curved le
 ft-invariant Kähler structure.\n\n(2) A second one\, joint with V.Gayral\
 , S. Neshveyev and L. Tuset\, where we construct locally compact quantum g
 roups from star products on a class of Lie groups.\n\nThe Lie groups on wh
 ich these deformations are performed (in both (1) and (2)) are of ``Froben
 ius type''. This means that their Lie algebras carry an exact non-degenera
 te two-cocycle or\, equivalently\, that they admit an open co-adjoint orbi
 t. In both cases\, the star products\, say at the formal level\, are of Fe
 dosov type i.e. associated with a left-invariant symplectic torsion free a
 ffine connection on the group manifold at hand. In particular\, they are o
 btained from differential theoretical considerations.\n\nHowever\, there i
 s a dichotomy: the orderings of the star products considered in (1) and (2
 ) are different. In (1)\, we deal with Weyl ordered star products\, while 
 in (2) with normal (or anti-normal) ones. This has\, apparently\, a strong
  effect on the regularity of the categories those constructions live in: s
 mooth versus measurable or topological.\nMore precisely:\nIn (1)\, we defi
 nitely deal with a ``smooth object''\, e.g. the universal deformation form
 ula (i.e. the twist) allows to deform smooth vectors of the group action\,
  e.g. they are relevant in differential noncommutative geometry in the sen
 se of A. Connes. But\, no locally compact quantum group is present there. 
 And until now\, I haven't be able to define a reasonable notion of ``smoot
 h quantum group'' attached to the construction.\nIn (2)\, the quantum grou
 p is present\, but the deformation procedure apparently breaks smoothness:
  smooth vectors of strongly continuous actions (i.e. smooth module-algebra
 s) of the group are not stable under twisting.\n\nIn the talk\, I will dis
 cuss  differential geometrical aspects of Frobenius Lie groups within this
  deformation quantization context. I will end with a suggestion based on t
 he possible use of a Lie group theoretical version of a\nmicrolocal analyt
 ical tool : Hörmander's smooth wave front set.\n
LOCATION:https://researchseminars.org/talk/QGS/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lucas Hataishi (University of Oslo\, Norway)
DTSTART:20220516T140000Z
DTEND:20220516T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/59
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/59/">Yet
 ter-Drinfeld algebras\, module categories and injectivity</a>\nby Lucas Ha
 taishi (University of Oslo\, Norway) as part of Quantum Groups Seminar [QG
 S]\n\n\nAbstract\nMany examples of quantum group actions carry a Yetter-Dr
 infeld structure. Among them\, you find C*-algebras coming from the bounda
 ry theory of Drinfeld doubles\, which is closely related to the theory of 
 ucp maps and injective envelopes of Hamana. Exploring Tannaka-Krein dualit
 y for quantum group actions\, it is possible to extend many concepts and r
 esults of boundary theory to the categorical setting\, but the lack of a c
 ategorification of non-braided-commutative Yetter-Drinfeld algebras impose
  an obstruction to a full analogy.\n\nIn this talk\, I will sketch how to 
 perform such a categorification and relate it to the study of injectivity 
 for module categories. Based on joint works with E. Habbestad\, S. Neshvey
 ev and M. Yamashita.\n
LOCATION:https://researchseminars.org/talk/QGS/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sebastian Halbig (TU Dresden\, Germany)
DTSTART:20220530T140000Z
DTEND:20220530T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/60
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/60/">Piv
 otality\, twisted centres and the anti-double of a Hopf monad</a>\nby Seba
 stian Halbig (TU Dresden\, Germany) as part of Quantum Groups Seminar [QGS
 ]\n\n\nAbstract\nPairs in involution are an algebraic structure whose syst
 ematic study\nis motivated by their applications in knot theory\, represen
 tation theory and\ncyclic homology theories.\n\nIn this talk\, we will exp
 lore a categorical view for these objects from the\nperspective of represe
 ntation theory of monoidal categories.\nA focus will lie on illustrating h
 ow their existence is linked to a particular\nwell-behaved notion of duali
 ty called pivotality.\nIn particular\, we will show how the language of mo
 nads allows us to combine\nthe algebraic with the categorical perspective 
 of these pairs.\n\nThis talk is based on the article arXiv:2201.05361.\n
LOCATION:https://researchseminars.org/talk/QGS/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Johan Konings (Vrije Universiteit Brussel\, Belgium)
DTSTART:20220606T140000Z
DTEND:20220606T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/61
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/61/">Par
 tial algebraic quantum groups and their Drinfeld doubles</a>\nby Johan Kon
 ings (Vrije Universiteit Brussel\, Belgium) as part of Quantum Groups Semi
 nar [QGS]\n\n\nAbstract\nIn this talk\, we will define partial algebraic q
 uantum groups\, which are special cases of weak multiplier Hopf algebras\,
  as introduced by Van Daele and Wang. At the same time\, they provide a ge
 neralization to the notion of a partial compact quantum group\, as introdu
 ced by De Commer and Timmermann. The main aim of the talk will be to reali
 ze the Drinfeld double of a partial compact quantum group as a partial alg
 ebraic quantum group. This talk is based on joint work with K. De Commer.\
 n
LOCATION:https://researchseminars.org/talk/QGS/61/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roland Vergnioux (Université de Caen\, France)
DTSTART:20220620T140000Z
DTEND:20220620T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/62
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/62/">Hec
 ke algebras and the Schlichting completion for discrete quantum groups</a>
 \nby Roland Vergnioux (Université de Caen\, France) as part of Quantum Gr
 oups Seminar [QGS]\n\n\nAbstract\nIn recent joint work with Skalski and Vo
 igt we construct and study the Hecke algebra and Hecke operators associate
 d with an almost normal subgroup in a discrete quantum group. We also give
  in this framework a quantum version of the Schlichting completion\, which
  yields an algebraic quantum group with a compact-open subgroup. We descri
 be a class of examples arising from HNN extensions.\n
LOCATION:https://researchseminars.org/talk/QGS/62/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roberto Hernández Palomares (Texas A&M University\, USA)
DTSTART:20220627T140000Z
DTEND:20220627T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/63
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/63/">Q-s
 ystems and higher unitary idempotent completion for C*-algebras</a>\nby Ro
 berto Hernández Palomares (Texas A&M University\, USA) as part of Quantum
  Groups Seminar [QGS]\n\n\nAbstract\nQ-systems were introduced by Longo to
  study finite index inclusions of infinite von Neumann factors. A Q-system
  is a unitary version of a Frobenius algebra object in a tensor category o
 r a C* 2-category. By the work of Müger\, Q-systems give an axiomatizatio
 n of the standard invariant of a finite index subfactor.\n\nFollowing work
  of Douglass-Reutter\, a Q-system is also a unitary version of a higher id
 empotent. In this talk\, we will describe a higher unitary idempotent comp
 letion for C* 2-categories called Q-system completion.\n\nOur main goal is
  to show that C*Alg\, the C* 2-category of right correspondences of unital
  C*-algebras is Q-system complete. To do so\, we will use the graphical ca
 lculus for C* 2-categories\, and adapt a subfactor reconstruction techniqu
 e called realization\, which is inverse to Q-system completion. This resul
 t allows for the straightforward adaptation of subfactor results to C*-alg
 ebras\, characterizing finite index extensions of unital C*-algebras equip
 ped with a faithful conditional expectation in terms of the Q-systems in C
 *Alg. If time allows\, we will discuss an application to induce new symmet
 ries of C*-algebras from old via Q-system completion.\n\nThis is joint wor
 k with Q. Chen\, C. Jones and D. Penneys (arXiv: 2105.12010).\n
LOCATION:https://researchseminars.org/talk/QGS/63/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Harshit Yadav (Rice University\, USA)
DTSTART:20220704T140000Z
DTEND:20220704T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/64
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/64/">Fil
 tered Frobenius algebras in monoidal categories</a>\nby Harshit Yadav (Ric
 e University\, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\
 nWe develop filtered-graded techniques for algebras in monoidal\ncategorie
 s with the goal of establishing a categorical version of Bongale's\n1967 r
 esult: A filtered deformation of a Frobenius algebra over a field is\nFrob
 enius as well. Towards the goal\, we construct a monoidal associated\ngrad
 ed functor\, building on prior works of Ardizzoni-Menini\, of Galatius et\
 nal.\, and of Gwillian-Pavlov. We then produce equivalent conditions for a
 n\nalgebra in a rigid monoidal category to be Frobenius in terms of the\ne
 xistence of categorical Frobenius form. These two results of independent\n
 interest are used to achieve our goal. As an application of our main\nresu
 lt\, we show that any exact module category over a symmetric finite\ntenso
 r category is represented by a Frobenius algebra in it. This is joint\nwor
 k with Dr. Chelsea Walton (Rice University)\n
LOCATION:https://researchseminars.org/talk/QGS/64/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Benjamin Anderson-Sackaney (Université de Caen\, France)
DTSTART:20221018T140000Z
DTEND:20221018T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/65
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/65/">Rel
 ative Amenability\, Amenability\, and Coamenability of Coideals</a>\nby Be
 njamin Anderson-Sackaney (Université de Caen\, France) as part of Quantum
  Groups Seminar [QGS]\n\n\nAbstract\nAmenability is a deeply studied prope
 rty of groups\, with many interesting reformulations and connections to th
 e operator algebraic aspects of groups. For example\, the reduced $C^*$-al
 gebra $C^*_r(G)$ of a discrete group has a unique tracial state if and onl
 y if there are no non-trivial amenable normal subgroups. This\, among othe
 r related results\, makes it apparent that the structure of the amenable s
 ubgroups of $G$ contains important information about $C^*_r(G)$. For a qua
 ntum group $\\mathbb{G}$\, an appropriate analogue of a subgroup is a coid
 eal $N\\subseteq L^\\infty(\\mathbb{G})$. We will present notions of relat
 ive amenability\, amenability\, and coamenability for coideals of discrete
  and compact quantum groups motivated by "relativizations" of amenability 
 and coamenability of a subgroup of a group. We will discuss the known rela
 tionships between these formally distinct notions and their relevance to c
 ertain properties of the reduced $C^*$-algebras of discrete quantum groups
 .\n
LOCATION:https://researchseminars.org/talk/QGS/65/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Magnus Landstad (Norwegian University of Science and Technology\, 
 Norway)
DTSTART:20221108T150000Z
DTEND:20221108T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/66
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/66/">Exo
 tic group algebras\, crossed products\, and coactions</a>\nby Magnus Lands
 tad (Norwegian University of Science and Technology\, Norway) as part of Q
 uantum Groups Seminar [QGS]\n\n\nAbstract\nIf $G$ is a locally compact gro
 up\, we have the full group C*-algebra $C^*(G)$ and the reduced $C^*_r(G)$
 . We call a C*-algebra properly between $C^*(G)$ and $C^*_r(G)$ exotic.\n\
 nSimilarly\, if $G$ acts on a C*-algebra $A$ we can form the full crossed 
 product $C^*(G\\ltimes A)$ and the reduced crossed product $C^*_r(G\\ltime
 s A)$. An exotic crossed product is a C*-algebra properly between the two.
  Work by Baum\, Guentner\, and Willett show that these algebras are releva
 nt to the Baum-Connes conjecture.\n\nWe think that the best way to study t
 hese algebras is by also looking at the corresponding dual theory of coact
 ions. I will discuss some of these aspects\, but there will be more questi
 ons than answers.\n\nThis is joint work with Steve Kaliszewski and John Qu
 igg.\n
LOCATION:https://researchseminars.org/talk/QGS/66/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alfons Van Daele (KU Leuven\, Belgium)
DTSTART:20221115T150000Z
DTEND:20221115T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/67
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/67/">Alg
 ebraic quantum hypergroups and duality</a>\nby Alfons Van Daele (KU Leuven
 \, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nLet $G$
  be a finite group and $H$ a subgroup. The set $\\mathcal{G}$ of double co
 sets $HpH$\, with $p \\in G$ has the structure of an hypergroup. The produ
 ct of two elements $HpH$ and $HqH$ is the set of cosets $HrH$ where $r \\i
 n pHq$. The algebra $A$ of functions on $\\mathcal{G}$ is the space of fun
 ctions on $G$ that are constant on double cosets. It carries a natural cop
 roduct\, dual to the product\, and given by\n$$∆(p\,q) = \\frac{1}{n} \\
 sum_{h \\in H} f(phq)$$\nwhere $n$ is the number of elements in $H$. The d
 ual algebra is known as the Hecke algebra associated with the pair $G\,H$.
 \nIn this talk I will discuss the notion of an algebraic quantum hypergrou
 p\, its fundamental properties and duality for algebraic quantum hypergrou
 ps.\nI will illustrate this with an example\, coming from bicrossproduct t
 heory\, constructed from a pair of closed subgroups $H$ and $K$ of a group
  $G$\, with the assumption that $H \\cap K = {e}$.\nThis is part of more g
 eneral work in progress with M. Landstad (NTNU\, Trondheim)\n
LOCATION:https://researchseminars.org/talk/QGS/67/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Erik Habbestad (Universityof Oslo\, Norway)
DTSTART:20221213T150000Z
DTEND:20221213T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/70
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/70/">C*-
 algebras associated to Temperley-Lieb polynomials</a>\nby Erik Habbestad (
 Universityof Oslo\, Norway) as part of Quantum Groups Seminar [QGS]\n\n\nA
 bstract\nWe define Temperley-Lieb polynomials and consider the (standard) 
 subproduct systems they generate. This subproduct system turns out to be e
 quivariant with respect to a compact quantum group G monoidally equivalent
  to $U_q(2)$. Exploiting this we are able to describe the C*-algebras asso
 ciated to the subproduct system\, which turn out to be closesly related to
  the linking algebra $B(U_q(2)\,G)$. This is joint work with Sergey Neshve
 yev.\n
LOCATION:https://researchseminars.org/talk/QGS/70/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fatemeh Khosravi (Seoul National University\, South Korea)
DTSTART:20221129T100000Z
DTEND:20221129T110000Z
DTSTAMP:20260422T145751Z
UID:QGS/72
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/72/">Co-
 amenable quantum homogeneous spaces of compact Kac quantum groups</a>\nby 
 Fatemeh Khosravi (Seoul National University\, South Korea) as part of Quan
 tum Groups Seminar [QGS]\n\n\nAbstract\nGiven a locally compact group G\, 
 Leptin's theorem states that G is amenable if and only if the Fourier alge
 bra A(G) admits a bounded approximate identity\, where the latter property
  is known as co-amenability of the quantum dual of G. In the quantum setti
 ng\, this characterization is known as the duality between amenability and
  co-amenability. It is proved that a discrete quantum group is amenable if
  and only if its dual compact quantum group is co-amenable. The definition
  of co-amenability for quantum homogeneous spaces is given by Kalantar-Kas
 przak-Skalski-Vergnioux. Furthermore\, they ask whether the co-amenability
  of a quantum homogeneous space is equivalent to the (relative) amenabilit
 y of its co-dual. In this talk\, we will answer this question for quantum 
 homogeneous spaces of compact Kac quantum groups under a mild assumption. 
 Based on joint work with Mehrdad Kalantar.\n
LOCATION:https://researchseminars.org/talk/QGS/72/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefaan Vaes (KU Leuven\, Belgium)
DTSTART:20221122T160000Z
DTEND:20221122T170000Z
DTSTAMP:20260422T145751Z
UID:QGS/75
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/75/">Qua
 ntum automorphism groups of connected locally finite graphs and quantizati
 ons of finitely generated groups</a>\nby Stefaan Vaes (KU Leuven\, Belgium
 ) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nI present a joint
  work with Lukas Rollier. We construct the quantum automorphism group of a
 ny connected locally finite\, possibly infinite\, graph as a locally compa
 ct quantum group that has the classical (locally compact) automorphism gro
 up as a closed quantum subgroup. For finite graphs\, we get the quantum au
 tomorphism group of Banica and Bichon. One of the key tools is the constru
 ction of a unitary tensor category associated with any connected locally f
 inite graph. When this graph is the Cayley graph of a finitely generated g
 roup\, the associated unitary tensor category has a canonical fiber functo
 r. We thus also obtain a quantization procedure for arbitrary finitely gen
 erated groups. In the particular example of groups defined by a triangle p
 resentation\, this construction gives the property (T) discrete quantum gr
 oups from earlier joint work with Valvekens.\n
LOCATION:https://researchseminars.org/talk/QGS/75/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kan Kitamura (University of Tokyo\, Japan)
DTSTART:20221220T150000Z
DTEND:20221220T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/77
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/77/">Par
 tial Pontryagin duality for actions of quantum groups on C*-algebras</a>\n
 by Kan Kitamura (University of Tokyo\, Japan) as part of Quantum Groups Se
 minar [QGS]\n\n\nAbstract\nWe compare actions on C*-algebras of two constr
 uctions of locally compact quantum groups\, the bicrossed product due to V
 aes-Vainerman and the double crossed product due to Baaj-Vaes. We give a o
 ne-to-one correspondence between them up to Morita equivalence\, in the sa
 me spirit as Takesaki-Takai and Baaj-Skandalis dualities. This includes a 
 duality between a quantum double and the product of the original quantum g
 roup with its opposite. We will explain its consequences for equivariant K
 asparov theory in relation to the quantum analog of the Baum-Connes conjec
 ture.\n
LOCATION:https://researchseminars.org/talk/QGS/77/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julia Plavnik (Indiana University Bloomington\, USA)
DTSTART:20230124T150000Z
DTEND:20230124T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/78
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/78/">Com
 paring different constructions of modular categories</a>\nby Julia Plavnik
  (Indiana University Bloomington\, USA) as part of Quantum Groups Seminar 
 [QGS]\n\n\nAbstract\nModular categories arise naturally in many areas of m
 athematics\, such as conformal field theory\, representations of braid gro
 ups\, quantum groups\, and Hopf algebras\, and low dimensional topology\, 
 and they have important applications in condensed matter physics.\n\nDespi
 te recent progress in the classification of modular categories\, we are st
 ill in the early stages of this theory and the general landscape remains l
 argely unexplored. One important step towards deepening our understanding 
 of modular categories is to have well-studied constructions. In this talk\
 , we will present an overview of various of these constructions and compar
 e their properties. We will focus on ribbon zesting and symmetry gauging\,
  and we will comment on some constructions in the G-crossed setting.\n
LOCATION:https://researchseminars.org/talk/QGS/78/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Daws (University of Central Lancashire\, UK)
DTSTART:20230131T150000Z
DTEND:20230131T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/79
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/79/">Aro
 und the Approximation Property for Quantum Groups</a>\nby Matthew Daws (Un
 iversity of Central Lancashire\, UK) as part of Quantum Groups Seminar [QG
 S]\n\n\nAbstract\nI will introduce what the "approximation property" (AP) 
 is for (locally compact) groups\, and provide a few applications.  I will 
 then talk about how one might give an analogous definition for (locally co
 mpact) quantum groups\, explaining some of the need technology along the w
 ay.  Time allowing\, I will discuss how the AP interacts with various comm
 on constructions\, and also about "central" versions and links with tensor
  categories.\n
LOCATION:https://researchseminars.org/talk/QGS/79/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oleg Aristov
DTSTART:20230207T150000Z
DTEND:20230207T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/80
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/80/">Com
 plex-analytic approach to quantum groups</a>\nby Oleg Aristov as part of Q
 uantum Groups Seminar [QGS]\n\n\nAbstract\nWe discuss quantum analogues of
  complex Lie groups. Our approach is closer to classical quantum group the
 ory than to C*-algebraic one (no multipliers and no invariant weights). I 
 propose to consider a topological Hopf algebra with a finiteness condition
  (holomorphically finitely generated or HFG for short). This topic seems 
 to offer a wide range of research opportunities.\n\nOur focus is on exampl
 es\, such as analytic forms of some classical quantum groups (a deformatio
 n of a solvable Lie group and Drinfeld-Jimbo algebras). I also present som
 e general results: (1) the category of Stein groups is anti-equivalent to 
 the category of commutative Hopf HFG algebras\; (2) If G is a compactly ge
 nerated Lie group\, the associated convolution cocommutative topological H
 opf algebra (introduced by Akbarov) is HFG. When\, in addition\, G is conn
 ected and linear\, the structure of this cocommutative algebra can be desc
 ribed explicitly. I also plan to discuss briefly holomorphic duality (whic
 h is parallel to Pontryagin duality).\n
LOCATION:https://researchseminars.org/talk/QGS/80/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Devarshi Mukherjee (University of Buenos Aires\, Argentina)
DTSTART:20230221T150000Z
DTEND:20230221T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/81
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/81/">Non
 commutative geometry in mixed characteristic</a>\nby Devarshi Mukherjee (U
 niversity of Buenos Aires\, Argentina) as part of Quantum Groups Seminar [
 QGS]\n\n\nAbstract\nI will give an overview of noncommutative topological 
 algebras and their cohomology theories in the setting of the p-adic intege
 rs.\n\nThis will entail constructions that are familiar from the complex c
 ase\, such as the formation of a smooth subalgebra of a C*-algebra.  The e
 xamples I will specialise these constructions to are group algebras of dis
 crete and p-adic Lie groups. It turns out that these are also examples of 
 bornological quantum groups (in the sense of Voigt). Finally\, if time per
 mits\, I will also discuss the computations of the Hochschild homology of 
 the completions of such algebras.\n
LOCATION:https://researchseminars.org/talk/QGS/81/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mao Hoshino (University of Tokyo\, Japan)
DTSTART:20230307T150000Z
DTEND:20230307T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/82
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/82/">Equ
 ivariant covering spaces of quantum homogeneous spaces</a>\nby Mao Hoshino
  (University of Tokyo\, Japan) as part of Quantum Groups Seminar [QGS]\n\n
 \nAbstract\nIn this talk I will explain the imprimitivity theorems for equ
 ivariant correspondences in two cases: for a general compact quantum group
  under a finiteness condition\, and for the Drinfeld-Jimbo deformation of 
 a semisimple compact Lie group. These results involve the representation\n
 theories of function algebras and the Tannaka-Krein duality for equivarian
 t correspondences. I also would like to give some applications if time all
 ows.\n
LOCATION:https://researchseminars.org/talk/QGS/82/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Melody Molander (University of California\, Santa Barbara\, USA)
DTSTART:20230314T150000Z
DTEND:20230314T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/83
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/83/">Ske
 in Theory for Affine ADE Subfactor Planar Algebras</a>\nby Melody Molander
  (University of California\, Santa Barbara\, USA) as part of Quantum Group
 s Seminar [QGS]\n\n\nAbstract\nSubfactor planar algebras first were constr
 ucted by Vaughan Jones as a diagrammatic axiomatization of the standard in
 variant of a subfactor. These planar algebras also encode two other invari
 ants of the subfactors: the index and the principal graph. The Kuperberg P
 rogram asks to find all diagrammatic presentations of subfactor planar alg
 ebras. This program has been completed for index less than 4. In this talk
 \, I will introduce subfactor planar algebras and give some presentations 
 of subfactor planar algebras of index 4 which have affine ADE Dynkin diagr
 ams as their principal graphs.\n
LOCATION:https://researchseminars.org/talk/QGS/83/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arthur Troupel (Université Paris Cité\, France)
DTSTART:20230214T150000Z
DTEND:20230214T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/84
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/84/">Fre
 e wreath products as fundamental graph C*-algebras</a>\nby Arthur Troupel 
 (Université Paris Cité\, France) as part of Quantum Groups Seminar [QGS]
 \n\n\nAbstract\nThe free wreath product of a compact quantum group by the 
 quantum permutation group $S_N^+$ has been introduced by Bichon in order t
 o give a quantum counterpart of the classical wreath product. The represen
 tation theory of such groups is well-known\, but some results about their 
 operator algebras were still open\, for example Haagerup property\, K-amen
 ability or factoriality of the von Neumann algebra. I will present a joint
  work with Pierre Fima in which we identify these algebras with the fundam
 ental C*-algebras of certain graphs of C*-algebras\, and we deduce these p
 roperties from these constructions.\n
LOCATION:https://researchseminars.org/talk/QGS/84/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yasuyuki Kawahigashi (University of Tokyo\, Japan)
DTSTART:20230328T110000Z
DTEND:20230328T120000Z
DTSTAMP:20260422T145751Z
UID:QGS/85
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/85/">Top
 ological order\, tensor networks and subfactors</a>\nby Yasuyuki Kawahigas
 hi (University of Tokyo\, Japan) as part of Quantum Groups Seminar [QGS]\n
 \n\nAbstract\nI will explain interactions between two-dimensional topologi
 cal order and subfactors from a viewpoint of tensor networks.  The range o
 f a certain finite dimensional projection appearing in statistical physics
  is identified with the higher relative commutant of the subfactor arising
  from such a tensor network.  We then work out the machinery of alpha-indu
 ction\nfor braided fusion categories in the setting of certain 4-tensors\,
  called bi-unitary connections\, appearing in subfactor theory.\n
LOCATION:https://researchseminars.org/talk/QGS/85/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Brannan (University of Waterloo\, Canada)
DTSTART:20230425T140000Z
DTEND:20230425T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/92
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/92/">No-
 signalling bicorrelations and generalized quantum automorphisms of graphs<
 /a>\nby Michael Brannan (University of Waterloo\, Canada) as part of Quant
 um Groups Seminar [QGS]\n\n\nAbstract\nI'll report on some recent joint wo
 rk with Sam Harris\,\nLyudmila Turowska and Ivan Todorov (arXiv:2302.04268
 )\, where we\nintroduce an analogue of bisynchronous correlations in the c
 ontext of\nquantum input-quantum output non-local games.  One of the main\
 nmotivations of this work was to find a non-local game interpretation of\n
 the quantum automorphisms and isomorphisms of quantum graphs that have\nap
 peared recently in the literature.  I'll explain how these\nconsiderations
  are related to tracial representations of quantum\nautomorphism groups of
  matrix algebras\, and in the case of ordinary\ngraphs\, lead us to a soft
 er (and possibly more general) notion of\nquantum symmetry for graphs.\n
LOCATION:https://researchseminars.org/talk/QGS/92/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mainak Ghosh (Indian Statistical Institute\, India)
DTSTART:20230620T090000Z
DTEND:20230620T100000Z
DTSTAMP:20260422T145751Z
UID:QGS/98
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/98/">Uni
 tary connections and Q-systems</a>\nby Mainak Ghosh (Indian Statistical In
 stitute\, India) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nTh
 e standard invariant plays a major role in subfactor theory. In this talk\
 , I will discuss a 2-categorical generalization of an axiomatization of th
 e standard invariant and further discuss some algebraic structures associa
 ted to it. This is based on joint work with P. Das\, S. Ghosh and C. Jones
  (arXiv:2211.03822) and on arxiv : 2302.04921.\n
LOCATION:https://researchseminars.org/talk/QGS/98/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joeri De Ro (Vrije Universiteit Brussel\, Belgium)
DTSTART:20230606T140000Z
DTEND:20230606T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/100
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/100/">Ac
 tions of compact and discrete quantum groups on operator systems</a>\nby J
 oeri De Ro (Vrije Universiteit Brussel\, Belgium) as part of Quantum Group
 s Seminar [QGS]\n\n\nAbstract\nWe introduce the notion of an action of a d
 iscrete or compact quantum group on an operator system\, and study equivar
 iant operator system injectivity. Given an action of a discrete quantum gr
 oup on an operator system X\, we introduce associated crossed products\, a
 nd we prove that equivariant injectivity of the operator system X is equiv
 alent with dual equivariant injectivity of the associated crossed products
 . As an application of this result\, we prove a duality result for equivar
 iant injective envelopes. This is joint work with Lucas Hataishi.\n
LOCATION:https://researchseminars.org/talk/QGS/100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mateusz Wasilewski (IMPAM\, Poland)
DTSTART:20231016T140000Z
DTEND:20231016T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/101
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/101/">Qu
 antum Cayley graphs</a>\nby Mateusz Wasilewski (IMPAM\, Poland) as part of
  Quantum Groups Seminar [QGS]\n\n\nAbstract\nI will talk about a method of
  associating a quantum graph to a discrete quantum group together with a p
 rojection in its function algebra. These quantum graphs are analogues of C
 ayley graphs and they do not depend on the choice of a generating projecti
 on in the sense of metric geometry. Later I will show how they can help in
  finding examples of finite quantum groups having Frucht property\, i.e. a
 rising as quantum automorphism groups of quantum graphs.\n\nPart of the ta
 lk will be based on an on-going joint work with Michael Brannan and Adam S
 kalski.\n
LOCATION:https://researchseminars.org/talk/QGS/101/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amaury Freslon (Université Paris-Saclay\, France)
DTSTART:20231023T140000Z
DTEND:20231023T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/102
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/102/">Cl
 assical actions of quantum permutations</a>\nby Amaury Freslon (Universit
 é Paris-Saclay\, France) as part of Quantum Groups Seminar [QGS]\n\n\nAbs
 tract\nQuantum permutation groups can act non-trivially\, and even ergodic
 ally\, on finite spaces. This is\, in view of many quantum rigidity result
 s\, an exception and it is natural to wonder whether there are other class
 ical spaces on which quantum permutations can act. H. Huang constructed a 
 family of such spaces\, and we will show that these are the only possibili
 ties. This is a joint work with F. Taipe and S. Wang.\n
LOCATION:https://researchseminars.org/talk/QGS/102/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Siegfried Echterhoff (WWU Münster\, Germany)
DTSTART:20231204T150000Z
DTEND:20231204T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/103
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/103/">Pr
 oper actions\, fixed-point algebras\, and deformation via coactions</a>\nb
 y Siegfried Echterhoff (WWU Münster\, Germany) as part of Quantum Groups 
 Seminar [QGS]\n\n\nAbstract\nThe notion of proper actions of groups on spa
 ces has various generalizations for group actions of noncommutative $C^*$-
 algebras $A$\, which all allow the construction of generalized fixed-point
  algebras $A^G$ which are Morita equivalent to ideals in the reduced cross
 ed products $A\\rtimes_rG$. The weakest version was introduced by  Rieffel
  in 1990 and it  played an important role in his theory of deformations vi
 a actions of $\\mathbb R^d$. In this talk we want to report on some joint 
 work with Alcides Buss on a version of proper actions which allows the con
 struction of maximal (or exotic) generalized fixed-point algebras which ar
 e Morita equivalent to ideals in the maximal (resp. exotic) crossed produc
 ts. We will report on several applications including Landstad duality for 
 coactions and deformation of C*-algebras via coactions in the sense of Kas
 przak and Bowmick\, Neshveyev\, and Sangha.\n
LOCATION:https://researchseminars.org/talk/QGS/103/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Benjamin Anderson-Sackaney (Université de Caen\, France)
DTSTART:20231113T150000Z
DTEND:20231113T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/104
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/104/">To
 pological Boundaries of Representations and Coideals</a>\nby Benjamin Ande
 rson-Sackaney (Université de Caen\, France) as part of Quantum Groups Sem
 inar [QGS]\n\n\nAbstract\nWe will introduce and study quantum analogues of
  Furstenberg-Hamana boundaries of representations of discrete quantum grou
 ps\, where the Furstenberg boundary is the Furstenberg-Hamana boundary of 
 the left regular representation. Our focus is on the GNS representations o
 f idempotent states\, or to put it differently\, the quasi-regular represe
 ntations coming from coideals associated to compact quasi-subgroups. We us
 e their Furstenberg-Hamana boundaries to study (co)amenability properties 
 of such coideals. Then\, we combine our work with recent work of Hataishi 
 and De Ro to settle open problems of Kalantar\, Kasprzak\, Skalski\, and V
 ergnioux for wide classes of quantum groups\, including unimodular discret
 e quantum groups and C*-exact discrete quantum groups. For example\, we pr
 ove that a unimodular discrete quantum group has the unique trace property
  iff it acts faithfully on its Furstenberg boundary.\n\nThis is joint work
  with Fatemeh Khosravi.\n
LOCATION:https://researchseminars.org/talk/QGS/104/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Yuncken (Université de Lorraine\, France)
DTSTART:20231120T150000Z
DTEND:20231120T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/105
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/105/">Cr
 ystallizing compact semisimple Lie groups</a>\nby Robert Yuncken (Universi
 té de Lorraine\, France) as part of Quantum Groups Seminar [QGS]\n\n\nAbs
 tract\nThe theory of crystal bases is a means of simplifying the represent
 ation theory of semisimple Lie algebras by passing through quantum groups.
   Varying the parameter q of the quantized enveloping algebras\, we pass f
 rom the classical theory at ​$q=1$ through the Drinfeld-Jimbo algebras a
 t $q\\in]0\,1[$ to the crystal limit at $q = 0$. At this point\, the main 
 features of the representation theory crystallize into purely combinatoria
 l data described by crystal graphs.  In this talk\, we will describe what 
 happens to the C*-algebra of functions on a compact semisimple Lie group u
 nder the crystallization process\, yielding higher-rank graph algebras. Th
 is is joint work with Marco Matassa.\n
LOCATION:https://researchseminars.org/talk/QGS/105/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Malte Gerhold (Saarland University\, Germany)
DTSTART:20231127T150000Z
DTEND:20231127T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/106
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/106/">Co
 homology of free unitary quantum groups</a>\nby Malte Gerhold (Saarland Un
 iversity\, Germany) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\
 nIn the talk\, we will discuss the free unitary quantum groups\n(or "unive
 rsal quantum groups") of Wang and van Daele from a\n(co)homological perspe
 ctive. We find a free resolution of the\ncounit\, a versatile tool which h
 elps to compute cohomological data such\nas Hochschild cohomology or bialg
 ebra cohomology of the associated Hopf\nalgebras. For free orthogonal quan
 tum groups\, such resolutions have been\nfound by Collins\, Härtel\, and 
 Thom (in the Kac-case) and Bichon (in the\ngeneral case)\, and they will s
 erve as our starting point for finding\nresolutions for free unitary quant
 um groups.\n\nBased on joint work with I. Baraquin\, U. Franz\, A. Kula an
 d M. Tobolski\n[arXiv:2309.07767<https://arxiv.org/abs/2309.07767>]\n
LOCATION:https://researchseminars.org/talk/QGS/106/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Uwe Franz (Université de Franche-Comté\, France)
DTSTART:20240122T150000Z
DTEND:20240122T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/107
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/107/">Ga
 ussian Parts of Compact Quantum Groups</a>\nby Uwe Franz (Université de F
 ranche-Comté\, France) as part of Quantum Groups Seminar [QGS]\n\n\nAbstr
 act\nWe introduce the Gaussian part of a compact quantum group G\, namely 
 the largest quantum subgroup of G supporting all the Gaussian functionals 
 of G. We prove that the Gaussian part is always contained in the Kac part\
 , and characterise Gaussian parts of classical compact groups\, duals of c
 lassical discrete groups and q-deformations of compact Lie groups. The not
 ion turns out to be related to a new concept of "strong connectedness" and
  we exhibit several examples of both strongly connected and totally strong
 ly disconnected compact quantum groups. Joint work with Amaury Freslon and
  Adam Skalski.\n
LOCATION:https://researchseminars.org/talk/QGS/107/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joeri De Ro (Vrije Universiteit Brussel\, Belgium)
DTSTART:20240129T150000Z
DTEND:20240129T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/108
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/108/">Eq
 uivariant injectivity of crossed products</a>\nby Joeri De Ro (Vrije Unive
 rsiteit Brussel\, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\nAb
 stract\nWe introduce the notion of a G-operator space\, which consists of 
 an action of a locally compact quantum group G on an operator space X\, an
 d we study the notion of G-equivariant injectivity for such an operator sp
 ace. We define a natural associated crossed product operator space X ⋊ G
 \, on which both the locally compact quantum group G and its dual act. We 
 completely characterise when these crossed products are equivariantly inje
 ctive with respect to these actions. We discuss how these results generali
 se and unify several recent results from the literature and we give some n
 ew applications.\n
LOCATION:https://researchseminars.org/talk/QGS/108/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sergio Girón Pacheco (KU Leuven\, Belgium)
DTSTART:20240205T150000Z
DTEND:20240205T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/109
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/109/">In
 tertwining techniques for actions of C*-tensor categories</a>\nby Sergio G
 irón Pacheco (KU Leuven\, Belgium) as part of Quantum Groups Seminar [QGS
 ]\n\n\nAbstract\nIntertwining techniques\, first used in the realm of C*-a
 lgebras in Elliott’s classification of AF-algebras\, have been essential
  in the classification theory of C*-algebras and their group actions. In t
 his talk I will discuss intertwining and how it appears in C*-classificati
 on\, I will then outline an adaptation of these techniques to the tensor c
 ategory equivariant setting. Time permitting I will discuss an application
  of these techniques to the study of tensor category equivariant Jiang-Su 
 stability.\n
LOCATION:https://researchseminars.org/talk/QGS/109/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kent Vashaw (Massachusetts Institute of Technology\, USA)
DTSTART:20240212T150000Z
DTEND:20240212T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/110
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/110/">Qu
 antum-symmetric equivalence via Manin's universal quantum groups</a>\nby K
 ent Vashaw (Massachusetts Institute of Technology\, USA) as part of Quantu
 m Groups Seminar [QGS]\n\n\nAbstract\nWe study 2-cocycle (and more general
 ly quantum-symmetric equivalences between) twists of graded algebras via t
 heir associated universal quantum groups\, in the sense of Manin. We prove
  that Zhang twists arise as a special case of 2-cocycle twist\, and that 2
 -cocyle twisting preserves many fundamental homological invariants of grad
 ed algebras. As a consequence\, we give a characterization of Artin--Schel
 ter regular algebras using the language of 2-cocycle twists.\n
LOCATION:https://researchseminars.org/talk/QGS/110/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lyudmila Turowska (Chalmers University of Technology and Universit
 y of Gothenburg\, Sweden)
DTSTART:20240304T150000Z
DTEND:20240304T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/111
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/111/">No
 -signalling values of cooperative quantum games</a>\nby Lyudmila Turowska 
 (Chalmers University of Technology and University of Gothenburg\, Sweden) 
 as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nFinding values\, th
 e optimal winning probability\, of various non-local games over different 
 strategies has been an important task in Quantum Information Theory and al
 so for resolving the Connes Embedding Problem. In this talk I will discuss
  values of quantum games (games with quantum inputs and outputs)\, arising
  from the type hierarchy of quantum no-signalling correlations\, establish
 ing operator space tensor norm expressions for each of the correlation typ
 es. This is a joint work with Jason Crann\, Rupert Levene and Ivan Todorov
 .\n
LOCATION:https://researchseminars.org/talk/QGS/111/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Laugwitz (University of Nottingham\, UK)
DTSTART:20240219T150000Z
DTEND:20240219T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/112
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/112/">In
 duced functors on Drinfeld centers</a>\nby Robert Laugwitz (University of 
 Nottingham\, UK) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nI 
 will explain how the right/left adjoint of a monoidal functor induced a br
 aided lax/oplax monoidal functors between the corresponding Drinfeld cente
 rs. This requires some mild technical assumptions\, namely that the projec
 tion formulas hold for the adjoint functor. This holds\, for example\, whe
 n the monoidal categories are rigid. As the induced functors on the Drinfe
 ld centers are (op)lax and compatible with braiding\, they preserve commut
 ative (co)algebra objects. As classes of examples\, we consider monoidal r
 estriction functors along extensions of Hopf algebras leading to (co)induc
 tion functors on Yetter-Drinfeld module categories. This is joint work in 
 progress with Johannes Flake (Bonn) and Sebastian Posur (Münster).\n
LOCATION:https://researchseminars.org/talk/QGS/112/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Victor Ostrik (University of Oregon\, USA)
DTSTART:20240311T170000Z
DTEND:20240311T180000Z
DTSTAMP:20260422T145751Z
UID:QGS/113
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/113/">Gr
 owth in tensor powers</a>\nby Victor Ostrik (University of Oregon\, USA) a
 s part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nThis talk is based o
 n joint work with K. Coulembier\, P. Etingof\, D. Tubbenhauer. Let $G$ be 
 any group and let $V$ be a finite dimensional representation of $G$ over s
 ome field. We consider tensor powers of $V$ and their decompositions into 
 indecomposable summands. The main question which will be addressed in this
  talk: what can we say about count (e.g. total number) of these indecompos
 able summands? It turns out that there are reasonable partial answers to t
 his question asymptotically\, i.e. when the tensor power is large.\n\nPlea
 se note the unusual time\n
LOCATION:https://researchseminars.org/talk/QGS/113/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chiara Esposito (University of Salerno\, Italy)
DTSTART:20240513T140000Z
DTEND:20240513T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/114
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/114/">Eq
 uivariant formality and reduction</a>\nby Chiara Esposito (University of S
 alerno\, Italy) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nIn 
 this talk\, we discuss the reduction-quantization diagram in terms of form
 ality. First\, we propose a reduction scheme for multivector fields and mu
 ltidifferential operators\, phrased in terms of L-infinity morphisms. This
  requires the introduction of equivariant multivector fields and equivaria
 nt multidifferential operator complexes\, which encode the information of 
 the Hamiltonian action\, i.e.\, a G-invariant Poisson structure allowing f
 or a momentum map. As a second step\, we discuss an equivariant version of
  the formality theorem\, conjectured by Tsygan and recently solved in a jo
 int work with Nest\, Schnitzer\, and Tsygan. This result has immediate con
 sequences in deformation quantization\, since it allows for obtaining a qu
 antum moment map from a classical momentum map with respect to a G-invaria
 nt Poisson structure.\n
LOCATION:https://researchseminars.org/talk/QGS/114/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward Pearce-Crump (Imperial College London\, UK)
DTSTART:20240520T140000Z
DTEND:20240520T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/115
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/115/">Co
 mpact Matrix Quantum Group Equivariant Neural Networks</a>\nby Edward Pear
 ce-Crump (Imperial College London\, UK) as part of Quantum Groups Seminar 
 [QGS]\n\n\nAbstract\nIn deep learning\, we would like to develop principle
 d approaches for constructing neural networks. One important approach invo
 lves identifying symmetries that are inherent in data and then encoding th
 em into neural network architectures using representations of groups. Howe
 ver\, there exist so-called “quantum symmetries” that cannot be unders
 tood formally by groups. In this talk\, we show how to construct neural ne
 tworks that are equivariant to compact matrix quantum groups using Woronow
 icz’s version of Tannaka-Krein duality. We go on to characterise the lin
 ear weight matrices that appear in these neural networks for a class of co
 mpact matrix quantum groups known as “easy”.  In particular\, we show 
 that every compact matrix group equivariant neural network is a compact ma
 trix quantum group equivariant neural network.\n
LOCATION:https://researchseminars.org/talk/QGS/115/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jacek Krajczok (Vrije Universiteit Brussel\, Belgium)
DTSTART:20240527T140000Z
DTEND:20240527T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/116
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/116/">Mo
 dular invariants of quantum groups</a>\nby Jacek Krajczok (Vrije Universit
 eit Brussel\, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\nAbstra
 ct\nA very interesting feature of compact quantum groups is that their Haa
 r integral\, which is a normal state on $L^{\\infty}(G)$\, can be non-trac
 ial. Via Tomita-Takesaki theory\, this gives rise to two groups of automor
 phisms: modular automorphisms and scaling automorphisms. One can use them 
 to define a number of invariants\, related to whether these automorphisms 
 are trivial\, inner or approximately inner. During the talk I'll introduce
  such invariants (also in the general locally compact case)\, discuss a co
 njecture related to one of them\, and present their calculation in the cas
 e of q-deformed compact\, simply connected\, semisimple Lie group $G_q$. T
 he talk is based on a joint work with Piotr Sołtan.\n
LOCATION:https://researchseminars.org/talk/QGS/116/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ken Goodearl (Universite of California Santa Barbara\, USA)
DTSTART:20240624T070000Z
DTEND:20240624T080000Z
DTSTAMP:20260422T145751Z
UID:QGS/117
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/117/">Sp
 ectra of quantum algebras</a>\nby Ken Goodearl (Universite of California S
 anta Barbara\, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\
 nThe talk will survey what is known and/or conjectured about the prime and
  primitive spectra of quantum algebras\, particularly quantized coordinate
  rings and related algebras such as quantized Weyl algebras. The topologic
 al structure of these spectra\, their relations with classical algebraic v
 arieties\, and their relations with each other will be discussed.\n
LOCATION:https://researchseminars.org/talk/QGS/117/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roland Vergnioux (Université de Caen\, France)
DTSTART:20240603T140000Z
DTEND:20240603T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/118
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/118/">Ma
 ximal amenability of the radial subalgebra in free quantum groups factors<
 /a>\nby Roland Vergnioux (Université de Caen\, France) as part of Quantum
  Groups Seminar [QGS]\n\n\nAbstract\nThe free orthogonal quantum groups $O
 ^+(N)$\, introduced by Shuzhou Wang\, are monoidally equivalent to the $SU
 _q(2)$ compact quantum groups\, but on an analytical level they behave muc
 h like the quantum duals of the classical free groups\, when $N > 2$. I wi
 ll review their definition and main properties\, and present a new result 
 about the maximal amenability of the associated radial MASA\, obtained in 
 recent joint work with Xumin Wang.\n
LOCATION:https://researchseminars.org/talk/QGS/118/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Gromada (Czech Technical University\, Czechia)
DTSTART:20240617T140000Z
DTEND:20240617T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/119
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/119/">Ca
 yley graphs: Symmetries\, quantizations\, and duality</a>\nby Daniel Groma
 da (Czech Technical University\, Czechia) as part of Quantum Groups Semina
 r [QGS]\n\n\nAbstract\nIn the talk\, we are going to quantize several aspe
 cts of Cayley graphs. First\, we are going to study quantum symmetries of 
 Cayley graphs of abelian groups. From the classical theory\, it is known t
 hat the Fourier transform diagonalizes the adjacency matrix of any such Ca
 yley graph.\nThis can be used to determine the graph's quantum automorphis
 m group. Secondly\, we are going to show\, how to quantize Cayley graphs o
 f abelian groups. We obtain a quantum graph by twisting the function algeb
 ra of the classical one. Finally\, we recall a classical\nconstruction tha
 t takes a distance regular Cayley graph of an abelian group or\, more gene
 rally\, a translation association scheme and constructs its dual by applyi
 ng the Fourier transform. We generalize this construction replacing abelia
 n groups by arbitrary finite quantum groups.\n
LOCATION:https://researchseminars.org/talk/QGS/119/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Matassa (Oslo Metropolitan University\, Norway)
DTSTART:20240701T140000Z
DTEND:20240701T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/120
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/120/">Eq
 uivariant quantizations of the positive nilradical and covariant different
 ial calculi</a>\nby Marco Matassa (Oslo Metropolitan University\, Norway) 
 as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nWe consider the pro
 blem of quantizing the positive nilradical of a complex semisimple Lie alg
 ebra of finite rank\, together with a certain fixed direct sum decompositi
 on. The decompositions we consider are in one-to-one correspondence with t
 otal orders on the simple roots\, and exhibit the nilradical as a direct s
 um of graded modules for appropriate Levi factors. We show that this situa
 tion can be quantized equivariantly as a finite-dimensional subspace withi
 n the positive part of the corresponding quantized enveloping algebra. Fur
 thermore\, we show that such subspaces give rise to left coideals\, with t
 he possible exception of components corresponding to some exceptional Lie 
 algebras\, and this property singles them out uniquely. Finally\, we discu
 ss how to use these quantizations to construct covariant first-order diffe
 rential calculi on quantum flag manifolds\, which coincide with those intr
 oduced by Heckenberger-Kolb in the irreducible case.\n
LOCATION:https://researchseminars.org/talk/QGS/120/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lukas Rollier (Katholieke Universiteit Leuven\, Belgium)
DTSTART:20240610T140000Z
DTEND:20240610T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/121
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/121/">Qu
 antum automorphism groups of discrete structures</a>\nby Lukas Rollier (Ka
 tholieke Universiteit Leuven\, Belgium) as part of Quantum Groups Seminar 
 [QGS]\n\n\nAbstract\nGiven any mathematical structure\, it is a natural qu
 estion to ask which quantum symmetries it admits. One can in general not h
 ope to find a quantum automorphism group for any structure in the framewor
 k of Kustermans-Vaes\, as a necessary condition for its existence is local
  compactness of the classical automorphism group. In recent work\, a wide 
 range of discrete structures\, those which are connected and locally finit
 e in a suitable sense\, were shown to admit an algebraic quantum automorph
 ism group. The main tool for their construction is a generalization of the
  Tannaka-Krein-Woronowicz reconstruction theorem. In particular\, this all
 ows to construct quantum automorphism groups of connected locally finite q
 uantum graphs\, such as Wasilewski's quantum Cayley graphs\, generalizing 
 joint results with Stefaan Vaes.\n
LOCATION:https://researchseminars.org/talk/QGS/121/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean Delhaye (Université Paris-Saclay\, France)
DTSTART:20241118T150000Z
DTEND:20241118T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/122
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/122/">Cu
 toff for the Brownian Motion on the Unitary Quantum Group</a>\nby Jean Del
 haye (Université Paris-Saclay\, France) as part of Quantum Groups Seminar
  [QGS]\n\n\nAbstract\nWe introduce an analog of the Brownian motion on fre
 e unitary quantum groups UN+​. We will discuss the construction of this 
 Brownian motion\, computing its cutoff\, where convergence to equilibrium 
 undergoes a sharp transition. We will also examine the cutoff profile\, an
 alyzing the fine-scale behavior of the total variation distance around the
  cutoff. Unlike classical or orthogonal quantum groups\, the study of UN+
 ​ has additional challenges\, such as non-absolute continuity\, distinct
  properties of its central algebra and inabilities to clearly identify a B
 rownian motion.\n
LOCATION:https://researchseminars.org/talk/QGS/122/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Malte Leimbach (Radboud University\, Netherlands)
DTSTART:20241216T150000Z
DTEND:20241216T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/123
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/123/">Co
 nvergence of Peter-Weyl Truncations of Compact Quantum Groups</a>\nby Malt
 e Leimbach (Radboud University\, Netherlands) as part of Quantum Groups Se
 minar [QGS]\n\n\nAbstract\nA fundamental principle of noncommutative geome
 try is to encode  geometric information by spectral data\, formalised in t
 he notion of  spectral triples. In physical practice there are\, however\,
  always obstructions on the  availability of such data\, and one might be 
 led to considering truncated  versions of spectral triples instead. In thi
 s talk we will take a closer look at this formalism and explore it  within
  the framework of compact quantum metric spaces. In particular we will con
 sider compact quantum groups as compact quantum  metric spaces when equipp
 ed with an invariant lip-norm. We will discuss complete Gromov-Hausdorff c
 onvergence of truncations  arising from the Peter-Weyl decomposition of a 
 compact quantum group.\n
LOCATION:https://researchseminars.org/talk/QGS/123/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julio Cáceres (Vanderbilt University\, USA)
DTSTART:20250203T150000Z
DTEND:20250203T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/125
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/125/">Ne
 w hyperfinite subfactors with infinite depth</a>\nby Julio Cáceres (Vande
 rbilt University\, USA) as part of Quantum Groups Seminar [QGS]\n\n\nAbstr
 act\nWe will present new examples of irreducible\, hyperfinite subfactors 
 with trivial standard invariant and interesting Jones indices. These are o
 btained by constructing new finite dimensional commuting squares. We will 
 use two graph planar algebra embedding theorems and the classification of 
 small index subfactors to show that our commuting square subfactors cannot
  have finite depth. We also present one-parameter families of commuting sq
 uares that\, by a classification result of Kawahigashi\, will also yield i
 rreducible infinite depth subfactors. This is joint work with Dietmar Bisc
 h.\n
LOCATION:https://researchseminars.org/talk/QGS/125/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hua Wang (Harbin Institute of Technology\, China)
DTSTART:20250414T140000Z
DTEND:20250414T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/126
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/126/">A 
 Theory of Locally Convex Hopf Algebras -- I. Basic Theory and Examples</a>
 \nby Hua Wang (Harbin Institute of Technology\, China) as part of Quantum 
 Groups Seminar [QGS]\n\n\nAbstract\nThis is the first of two talks on a re
 cent theory of locally convex Hopf algebras. After a brief introduction to
  some relevant facts on locally convex spaces as well as their topological
  tensor products\, we will describe the main theory with an emphasis on du
 ality. We will see that besides the usual strong dual\, the theory encompa
 sses naturally a new type of dual called the polar dual. After presenting 
 the main theoretical results\, we will illustrate the theory with various 
 examples. In particular\, we will see how to resolve the duality problem f
 or classical Hopf algebras\, how to describe a Lie group as well as its du
 al using smooth functions\, and how to incorporate compact and discrete qu
 antum groups into this framework.\n
LOCATION:https://researchseminars.org/talk/QGS/126/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roberto Hernández Palomares (University of Waterloo\, Canada)
DTSTART:20250317T150000Z
DTEND:20250317T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/127
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/127/">Qu
 antum graphs\, subfactors and tensor categories</a>\nby Roberto Hernández
  Palomares (University of Waterloo\, Canada) as part of Quantum Groups Sem
 inar [QGS]\n\n\nAbstract\nWe will introduce equivariant graphs with respec
 t to a quantum symmetry along with examples such as classical graphs\, Cay
 ley graphs of finite groupoids\, and their quantum analogues. These graphs
  can be presented concretely by modeling a quantum vertex set by an inclus
 ion of operator algebras and the quantum edge set by an equivariant endomo
 rphism\, idempotent with respect to convolution/Schur product. Equipped wi
 th this viewpoint and tools from subfactor theory\, we will see how to obt
 ain all these idempotents using higher relative commutants and the quantum
  Fourier transform. Finally\, we will state a quantum version of Frucht's 
 Theorem\, showing that every quasitriangular finite quantum groupoid arise
 s as certain automorphisms of some categorified graph.\n
LOCATION:https://researchseminars.org/talk/QGS/127/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sang-Gyun Youn (Seoul National University\, South Korea)
DTSTART:20250331T080000Z
DTEND:20250331T090000Z
DTSTAMP:20260422T145751Z
UID:QGS/128
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/128/">A 
 Khintchine inequality for central Fourier series on non-Kac compact quantu
 m groups</a>\nby Sang-Gyun Youn (Seoul National University\, South Korea) 
 as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nThe study of Khintc
 hine inequalities has a long history in abstract harmonic analysis. While 
 there is almost no possibility of non-trivial Khintchine inequality for ce
 ntral Fourier series on compact connected semisimple Lie groups\, it has t
 urned out that a strong contrast holds within the framework of compact qua
 ntum groups. Specifically\, a Khintchine inequality with operator coeffici
 ents is proved for arbitrary central Fourier series in a large class of no
 n-Kac compact quantum groups. The main examples include the Drinfeld-Jimbo
  q-deformations\, the free orthogonal quantum groups\, and the quantum aut
 omorphism groups.\n
LOCATION:https://researchseminars.org/talk/QGS/128/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Heon Lee (Harbin Institute of Technology\, China)
DTSTART:20250407T120000Z
DTEND:20250407T130000Z
DTSTAMP:20260422T145751Z
UID:QGS/129
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/129/">Fi
 rst-order differential calculi and Laplacians on $q$-deformations of compa
 ct semisimple Lie groups</a>\nby Heon Lee (Harbin Institute of Technology\
 , China) as part of Quantum Groups Seminar [QGS]\n\n\nAbstract\nIn this ta
 lk\, we suggest a simple definition of Laplacian on a compact quantum grou
 p (CQG) associated with a first-order differential calculus (FODC) on it. 
 Applied to the classical differential calculus on a compact Lie group\, th
 is definition yields classical Laplacians\, as it should. Moreover\, on th
 e CQG $ K_q $ arising from the $ q $-deformation of a compact semisimple L
 ie group $K$\, we can find many interesting linear operators that satisfy 
 this definition\, which converge to a classical Laplacian on $ K $ as $ q 
 $ tends to 1. In the light of this\, we call them $ q $-Laplacians on $ K_
 q $ and investigate some of their operator theoretic properties. In partic
 lar\, we show that the heat semigroups generated by these are not complete
 ly positive\, suggesting that perhaps on the CQG $ K_q $\, stochastic proc
 esses that are most relevant to the geometry of it are not quantum Markov 
 processes. This work is based on the preprint arXiv:2410.00720.\n
LOCATION:https://researchseminars.org/talk/QGS/129/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hua Wang (Harbin Institute of Technology\, China)
DTSTART:20250421T140000Z
DTEND:20250421T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/130
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/130/">A 
 Theory of Locally Convex Hopf Algebras -- II. More Duality Results and Exa
 mples</a>\nby Hua Wang (Harbin Institute of Technology\, China) as part of
  Quantum Groups Seminar [QGS]\n\n\nAbstract\nThis is the second of two tal
 ks on a recent theory of locally convex Hopf algebras. We will start by pr
 esenting a generalized version of the Gelfand duality\, and later apply it
  in various situations to obtain the underlying topological group from the
  corresponding locally convex Hopf algebras. Surprisingly\, we can go much
  beyond the locally compact case in this classical situation\, and make th
 e theory work for all topological groups with compactly generated topology
 . Then we shift to some categorical considerations\, allowing us to obtain
  new topological quantum groups as well as their dualities that seem not i
 n the locally compact framework of Kustermans-Vaes. If time permits\, we w
 ill conclude by mentionning how some deep structural results related to Hi
 lbert's fifth problem can be applied in this theory.\n
LOCATION:https://researchseminars.org/talk/QGS/130/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Farrokh Razavinia (Institute for Research in Fundamental Sciences\
 , Iran)
DTSTART:20250519T140000Z
DTEND:20250519T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/131
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/131/">C*
 -graph algebras and beyond</a>\nby Farrokh Razavinia (Institute for Resear
 ch in Fundamental Sciences\, Iran) as part of Quantum Groups Seminar [QGS]
 \n\n\nAbstract\nGraph C*-algebras have shown their importance in mathemati
 cs and other disciplines. For instance\, recall the theory of quantum grou
 ps and quantum graphs\, they can provide us with required structures in pr
 oving or disproving some interrelated problems. For example\, in our recen
 t papers\, we showed their importance in looking at some very well-known w
 onder questions in mathematics from a different direction. In this talk\, 
 we will present some elementary definitions and results concerning graph C
 *-algebras\, and then we will try to study some constructive examples\, an
 d after that we will take a look at the concept of C*-colored graph algebr
 as\, and finally we will see how these structures will help us to move int
 o some very abstract mathematical object!\n
LOCATION:https://researchseminars.org/talk/QGS/131/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kenny De Commer (Vrije Universiteit Brussel\, Belgium)
DTSTART:20251103T150000Z
DTEND:20251103T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/132
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/132/">Br
 aided tensor product of von Neumann algebras</a>\nby Kenny De Commer (Vrij
 e Universiteit Brussel\, Belgium) as part of Quantum Groups Seminar [QGS]\
 n\n\nAbstract\nWork of Meyer\, Roy and Woronowicz has shown that the categ
 ory of C*-algebras with an action by a quasi-triangular quantum group admi
 ts a monoidal structure by means of a braided tensor product. We have show
 n that a similar result holds if instead we work with actions on von Neuma
 nn algebras. Moreover\, particular to this setting\, we are able to show h
 ow (part of the) modular theory of a braided tensor product behaves. We wi
 ll frame the latter result in a more general setting of cocycle deformatio
 ns. This is joint work with J. Krajczok.\n
LOCATION:https://researchseminars.org/talk/QGS/132/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joeri De Ro (IMPAN\, Poland)
DTSTART:20251110T150000Z
DTEND:20251110T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/133
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/133/">Eq
 uivariant Eilenberg-Watts theorems for locally compact quantum groups</a>\
 nby Joeri De Ro (IMPAN\, Poland) as part of Quantum Groups Seminar [QGS]\n
 \n\nAbstract\nGiven actions of a locally compact quantum group $G$ on the 
 von Neumann algebras $A$ and $B$\, we can associate to it the category $\\
 operatorname{Corr}^G(A\,B)$ of G-A-B-correspondences. Special cases of thi
 s category include the category $\\operatorname{Rep}(A)$ of unital\, norma
 l $*$-representations of $A$ on Hilbert spaces and the category $\\operato
 rname{Rep}^G(A)$ of unital\, normal\, $G$-representations on Hilbert space
 s. We construct actions $\\operatorname{Rep}^G(A)\\curvearrowleft \\operat
 orname{Rep}(G)$ and $\\operatorname{Rep}(A)\\curvearrowleft \\operatorname
 {Rep}(\\hat{G})$\, providing us with natural examples of module categories
 . We show that the categories of module functors $\\operatorname{Rep}(B)\\
 to \\operatorname{Rep}(A)$ and \n$\\operatorname{Rep}^G(B)\\to \\operatorn
 ame{Rep}^G(A)$ are both equivalent to the category of $G$-$A$-$B$-correspo
 ndences\, providing equivariant versions of the von Neumann algebraic Eile
 nberg-Watts theorem.\n
LOCATION:https://researchseminars.org/talk/QGS/133/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Milan Donvil (École normale supérieure - PSL\, France)
DTSTART:20251117T150000Z
DTEND:20251117T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/134
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/134/">W*
 -superrigidity for discrete quantum groups</a>\nby Milan Donvil (École no
 rmale supérieure - PSL\, France) as part of Quantum Groups Seminar [QGS]\
 n\n\nAbstract\nA (countable) group is called W*-superrigid if it is comple
 tely remembered by its group von Neumann algebra in the following sense: i
 f another group gives rise to an isomorphic group von Neumann algebra\, th
 e groups must be isomorphic. In the past fifteen years\, several classes o
 f W*-superrigid groups have been found. However\, it turns out that many o
 f these groups are not W*-superrigid in the larger class of compact quantu
 m groups: their group von Neumann algebras admit different quantum group s
 tructures. In a recent work with Stefaan Vaes\, we found the first example
 s of compact quantum groups which are 'quantum W*-superrigid'. To obtain q
 uantum W*-superrigidity\, we had to combine three different types of resul
 ts: vanishing of cohomology\, rigidity of (quantum) groups relative to a f
 amily of (quantum) group automorphisms\, and deformation/rigidity theory. 
 I will explain why each of these three parts is essential and how they com
 e together to prove our main result.\n
LOCATION:https://researchseminars.org/talk/QGS/134/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Leandro Vendramin (Vrije Universiteit Brussel\, Belgium)
DTSTART:20251124T150000Z
DTEND:20251124T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/135
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/135/">Ni
 chols algebras over (solvable) groups</a>\nby Leandro Vendramin (Vrije Uni
 versiteit Brussel\, Belgium) as part of Quantum Groups Seminar [QGS]\n\n\n
 Abstract\nNichols algebras appear in various areas of mathematics\, rangin
 g from Hopf algebras and quantum groups to Schubert calculus and conformal
  field theory. In this talk\, I will review the main challenges in classif
 ying Nichols algebras over groups and discuss some recent classification t
 heorems. In particular\, I will highlight a recent classification result (
 https://arxiv.org/abs/2411.02304)\, achieved in collaboration with Andrusk
 iewitsch and Heckenberger\, concerning finite-dimensional Nichols algebras
  over solvable groups.\n
LOCATION:https://researchseminars.org/talk/QGS/135/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Jaklitsch (University of Oslo\, Norway)
DTSTART:20251216T150000Z
DTEND:20251216T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/136
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/136/">Th
 e braided monoidal structure of tube algebra representations</a>\nby David
  Jaklitsch (University of Oslo\, Norway) as part of Quantum Groups Seminar
  [QGS]\n\n\nAbstract\nOcneanu's tube algebra plays a central role in latti
 ce models of Levin-Wen type\, where topological excitations are given by i
 rreducible representations. The purpose of the talk is to report on our re
 cent results explicitly describing the tensor product of tube algebra repr
 esentations and the braiding. The well-known linear equivalence between tu
 be algebra representations and the Drinfeld center category is (by means o
 f this structure) upgraded to a braided monoidal equivalence. This is join
 t work with Makoto Yamashita.\n
LOCATION:https://researchseminars.org/talk/QGS/136/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jennifer Brown (University of Edinburgh\, UK)
DTSTART:20260119T150000Z
DTEND:20260119T160000Z
DTSTAMP:20260422T145751Z
UID:QGS/137
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/137/">Pa
 rabolic Reduction and Quantum Character Varieties</a>\nby Jennifer Brown (
 University of Edinburgh\, UK) as part of Quantum Groups Seminar [QGS]\n\n\
 nAbstract\nCharacter varieties parametrise G-local systems on topological 
 spaces\, for G a reductive group. They play a central role in physical mod
 els such as Chern-Simons theory and have been widely studied. Many constru
 ctions involving character varieties can be formulated with a combination 
 of skein theory and parabolic reduction along a Borel subgroup of G.\n\nWe
 'll tell this story\, with the guiding goal of defining quantum cluster co
 ordinates on quantised character varieties. This is based on joint work wi
 th David Jordan.\n
LOCATION:https://researchseminars.org/talk/QGS/137/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Gui (Tsinghua University\, China)
DTSTART:20260126T080000Z
DTEND:20260126T090000Z
DTSTAMP:20260422T145751Z
UID:QGS/138
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/138/">Co
 mparison of extensions of unitary VOAs and conformal nets</a>\nby Ben Gui 
 (Tsinghua University\, China) as part of Quantum Groups Seminar [QGS]\n\n\
 nAbstract\nIn 2015\, Carpi-Kawahigashi-Longo-Weiner (CKLW) initiated a sys
 tematic study of the relationship between unitary vertex operator algebras
  (UVOAs) and conformal nets (CNs). Building on their framework and Wasserm
 ann’s computation of the Connes fusion of modules of loop group SU(N) at
  positive integer levels\, I showed in 2018 and 2020 that many rational UV
 OAs (including all WZW models) and their corresponding CNs have unitarily 
 equivalent representation categories.\n\nIn this talk\, I will show that w
 hen one considers extensions of UVOAs and CNs\, the abstract equivalence o
 f representation categories arising from the theory of Frobenius algebras 
 and Q-systems is compatible with the unitary equivalences (in the line of 
 CKLW and Wassermann) mentioned above.\n
LOCATION:https://researchseminars.org/talk/QGS/138/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alfons Van Daele (KU Leuven\, Belgium)
DTSTART:20260413T140000Z
DTEND:20260413T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/139
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/139/">Di
 screte quantum groups</a>\nby Alfons Van Daele (KU Leuven\, Belgium) as pa
 rt of Quantum Groups Seminar [QGS]\n\n\nAbstract\nDiscrete quantum groups 
 were first introduced as the duals of  compact quantum groups in a paper b
 y Podleś and Woronowicz (1990). Later they were studied independently by 
 Effros and Ruan (1994) and myself (1996). All of this was done before the 
 duality of multiplier Hopf algebras with integrals was developed (1998)\, 
 as a special and motivating  case  of the theory of locally compact quantu
 m groups\, developed even later (2000).\n\nUnfortunately\, also in more re
 cent work\, discrete quantum groups have still been treated as duals of co
 mpact quantum groups and not as a concept of its own.\n\nIn this talk I wi
 ll discuss a somewhat updated version of the theory of discrete quantum gr
 oups. Given a discrete quantum group $(A\,\\Delta)$\, I will focus on the 
 properties of $\\Delta(h)$ where $h$ is the cointegral. The element $\\Del
 ta(h)$ is a \\emph{separability idempotent} in the multiplier algebra $M(A
 \\otimes A)$ carrying all the essential  information about the discrete qu
 antum group. \n\nI plan to use the discrete quantum group that arises from
  the Jimbo deformation of the enveloping algebra of the Lie algebra of $SU
 (2)$ to illustrate some of the notions and properties of general discrete 
 quantum groups.\n
LOCATION:https://researchseminars.org/talk/QGS/139/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Keshab Bakshi (IIT Kanpur\, India)
DTSTART:20260330T140000Z
DTEND:20260330T150000Z
DTSTAMP:20260422T145751Z
UID:QGS/141
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QGS/141/">We
 ak quantum hypergroups from finite index $C^*$-inclusions</a>\nby Keshab B
 akshi (IIT Kanpur\, India) as part of Quantum Groups Seminar [QGS]\n\n\nAb
 stract\nWe study finite index inclusions $B \\subset A$ of simple unital $
 C^*$-algebras and investigate the quantum symmetries arising from their re
 lative commutants. Using the convolution structure on higher relative comm
 utants\, we construct a canonical completely positive coproduct on the sec
 ond relative commutant $B^{\\prime} \\cap A_1$\, which gives it a natural 
 coalgebra structure. This leads to the notion of a weak quantum hypergroup
 . We show that such a structure arises canonically from any finite index i
 nclusion. In the irreducible case it becomes a quantum hypergroup\, while 
 in the depth $2$ case it recovers the weak Hopf algebra associated with th
 e inclusion. This is a joint work with  Debashish Goswami and Biplab Pal\
 n
LOCATION:https://researchseminars.org/talk/QGS/141/
END:VEVENT
END:VCALENDAR