Reminder: Two NCG seminars

[Ludwik Dabrowski]

Stefan Wagner
BTH, University in Karlskrona, Sweden

1. "Factor systems as a computational framework
for noncommutative principal bundles"

Free actions in the sense of Ellwood provide a natural framework
for noncommutative principal bundles, which are becoming increasingly
prevalent in various applications to noncommutative geometry
and mathematical physics.
One of the key features of free actions of compact quantum groups are their
associated factor systems, which make them accessible to classification,
K-theoretic considerations, and computations in general.
In this talk we introduce the theory of factor systems for free actions
of compact quantum groups and discuss a few applications.

Wednesday 6 April 11:00-12:30,SISSA room 128/129

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2. "Lifting spectral triples to noncommutative principal bundles"

Given a free action of a compact Lie group G on a unital C*-algebra A
and a spectral triple on the corresponding fixed point algebra B,
we present a systematic construction of a spectral triple on A
that is build upon the geometry of B and G.
The procedure is based on our factor system theory introduced in the first talk.

Wednesday 6 April 15:30-17:00, SISSA room 132

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Based on:
"Free actions of compact Abelian groups on C*-algebras Part I", Adv. Math. 317 (2017), 224-266
and
Lifting spectral triples to noncommutative principal bundles", Adv. Mathh. 396 (2022) 108160
with Kay Schwieger.

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