Strongly self-absorbing C*-dynamical systems, III

Gabor Szabo

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15 Citations (Scopus)
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In this paper, we accomplish two objectives. Firstly, we extend and improve some results in the theory of (semi-)strongly self-absorbing ⁎C⁎-dynamical systems, which was introduced and studied in previous work. In particular, this concerns the theory when restricted to the case where all the semi-strongly self-absorbing actions are assumed to be unitarily regular, which is a mild technical condition. The central result in the first part is a strengthened version of the equivariant McDuff-type theorem, where equivariant tensorial absorption can be achieved with respect to so-called very strong cocycle conjugacy.Secondly, we establish completely new results within the theory. This mainly concerns how equivariantly Z-stable absorption can be reduced to equivariantly UHF-stable absorption with respect to a given semi-strongly self-absorbing action. Combining these abstract results with known uniqueness theorems due to Matui and Izumi–Matui, we obtain the following main result. If G is a torsion-free abelian group and D is one of the known strongly self-absorbing ⁎C⁎-algebras, then strongly outer G-actions on D are unique up to (very strong) cocycle conjugacy. This is new even for Z3-actions on the Jiang–Su algebra.
Original languageEnglish
Pages (from-to)356-380
Number of pages25
JournalAdvances in Mathematics
Early online date24 Jul 2017
Publication statusPublished - 20 Aug 2017

Bibliographical note

The work presented in this paper has benefited from a visit to the Department of Mathematics at the University of Kyoto in January 2016, and I would like to express my gratitude to Masaki Izumi for the hospitality and support.
Open Access funded by Engineering and Physical Sciences Research Council


  • Strongly self-absorbing C*-algebra
  • Noncommutative dynamical systems


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