Starting with a spectral triple on a unital C⁎-algebra A with an action of a discrete group G, if the action is uniformly bounded (in a Lipschitz sense) a spectral triple on the reduced crossed product C⁎-algebra A⋊rG is constructed in [23]. The main instrument is the Kasparov external product. We note that this construction still works for twisted crossed products when the twisted action is uniformly bounded in the appropriate sense. Under suitable assumptions we discuss some basic properties of the resulting triples: summability and regularity. Noncommutative coverings with finite abelian structure group are among the most basic, still interesting, examples of twisted crossed products; we describe their main features.
A note on twisted crossed products and spectral triples
Antonini P.;
2022-01-01
Abstract
Starting with a spectral triple on a unital C⁎-algebra A with an action of a discrete group G, if the action is uniformly bounded (in a Lipschitz sense) a spectral triple on the reduced crossed product C⁎-algebra A⋊rG is constructed in [23]. The main instrument is the Kasparov external product. We note that this construction still works for twisted crossed products when the twisted action is uniformly bounded in the appropriate sense. Under suitable assumptions we discuss some basic properties of the resulting triples: summability and regularity. Noncommutative coverings with finite abelian structure group are among the most basic, still interesting, examples of twisted crossed products; we describe their main features.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
