Link do kanału youtube: https://www.youtube.com/channel/UCnHfrrAKk9Jaaw8oC2s_dSQ

Zoom platform link: https://us02web.zoom.us/j/83662713532?pwd=MFpVS1NlQkt4THVtMGdYNTR2Ym93UT09

Meeting ID: 836 6271 3532 Passcode: 764579

- Paul F. Baum
- Francesco D'Andrea
- Ludwik Dąbrowski
- Søren Eilers
- Piotr M. Hajac
- Frédéric Latrémolière
- Ryszard Nest
- Marc A. Rieffel
- Andrzej Sitarz
- Wojciech Szymański
- Adam Wegert

2022-03-23, 17:15, ZOOM

RALF MEYER (Universität Göttingen)

**C*-ALGEBRAS DEFINED BY GROUPOID CORRESPONDENCES**In this talk, I define correspondences between étale groupoids, and show that they contain topological graphs and self-similarities of groups and graphs as special cases. A correspondence between two groupoids induces a C*-correspondence between the groupoid C...

2022-03-16, 17:15, ZOOM

XIANG TANG (Washington University in St. Louis)

**THE HELTON-HOWE TRACE, THE CONNES-CHERN CHARACTER, AND QUANTIZATION**In the early 70s, Helton and Howe proved a beautiful formula for the trace of commutators of Toeplitz operators. In the 80s, Connes greatly generalized the Helton-Howe trace formula using cyclic cohomology. The Connes-Chern character contains the Helton-Howe trace as the top degree compone...

2022-03-09, 17:15, ZOOM

RYSZARD NEST (Københavns Universitet)

**PROJECTIVE REPRESENTATION THEORY FOR COMPACT QUANTUM GROUPS AND THE BAUM-CONNES ASSEMBLY MAP**We study the theory of projective representations for a compact quantum group G, i.e. actions of G on B(H) for some Hilbert space H. We show that any such projective representation is inner, and hence is induced by an Ω-twisted representation for some unitary...

2022-03-02, 17:15, ZOOM

YANG LIU (SISSA)

**CYCLIC STRUCTURE BEHIND THE MODULAR GAUSSIAN CURVATURE**The modular Gaussian curvature on noncommutative two-tori introduced by Connes and Moscovici leads to a functional relation derived from its variational nature, which is a novel feature purely due to the noncommutativity. I will begin with the differential calculus behind the curvature computation, ...

2022-01-26, 17:15, ZOOM

TOMASZ MASZCZYK (Uniwersytet Warszawski)

**THE MULTIPLICATIVE K-THEORY TYPE OF QUANTUM CW-COMPLEXES**We enhance current noncommutative methods in topology to distinguish some very different classical homotopy types (e.g., a disconnected and a connected one) of finite CW-complexes, which cannot be distinguished using the Kasparov KK-theory. We achieve this by constructing a noncommutative counterpar...

2022-01-19, 17:15, ZOOM

SOPHIE EMMA MIKKELSEN (Syddansk Universitet)

**ON THE CLASSIFICATION OF QUANTUM LENS SPACES**There are many noncommutative deformations of classical spaces. For instance, the C*-algebras of quantum lens spaces can be defined as fixed-point subalgebras of the C*-algebras of Vaksman-Soibelman quantum spheres under actions of finite cyclic groups. Hong and Szymański described both the quantum...

2022-01-12, 17:15, ZOOM

BRAM MESLAND (Universiteit Leiden)

**NONCOMMUTATIVE RIEMANNIAN PRINCIPAL BUNDLES**In this talk, I will present a notion of principal G-spectral triple, with G a compact Lie group, put forward in my joint work with B. Ćaćić (New Brunswick). Our notion connects the algebraic approach to noncommutative principal bundles via principal comodule algebras and strong connections to th...

2021-12-22, 17:15, ZOOM

JONATHAN ROSENBERG (University of Maryland)

**POSITIVE SCALAR CURVATURE ON MANIFOLDS WITH BOUNDARY**Since work of Gromov and Lawson around 1980, we have known (under favorable circumstances) necessary and sufficient conditions for a closed manifold to admit a Riemannian metric of positive scalar curvature, but not much was known about analogous results for manifolds with boundary (and suitable bou...

2021-12-15, 17:15, ZOOM

ADAM SIKORA (SUNY Buffalo)

**STATED SKEIN ALGEBRAS AND A GEOMETRIC APPROACH TO QUANTUM GROUPS**We introduce the theory of stated SL(n)-skein algebras of surfaces, which provide a geometric/combinatorial interpretation for the quantum groups Oq(sl(n)) and other related notions from quantum algebra. They also quantize the SL(n)-character varieties of surfaces, are examples o...

2021-12-08, 17:15, ZOOM

PIOTR M. HAJAC (IMPAN)

**THE K-THEORY TYPE OF QUANTUM CW-COMPLEXES**The CW-complex structure of topological spaces not only reveals how they are built, but also is a natural tool to compute and unravel their K-theory. Therefore, it is desirable to define a noncommutative version of the CW-complex that would play a similar role in noncommutative topology. From some q...