English

The pure extension property for discrete crossed products

Operator Algebras 2017-08-28 v2

Abstract

Let GG be a discrete group acting on a unital CC^*-algebra A\mathcal{A} by *-automorphisms. In this note, we show that the inclusion AArG\mathcal{A} \subseteq \mathcal{A} \rtimes_r G has the pure extension property (so that every pure state on A\mathcal{A} extends uniquely to a pure state on ArG\mathcal{A} \rtimes_r G) if and only if GG acts freely on A^\mathcal{\widehat{A}}, the spectrum of A\mathcal{A}. The same characterization holds for the inclusion AAG\mathcal{A} \subseteq \mathcal{A} \rtimes G. This generalizes what was already known for A\mathcal{A} abelian.

Keywords

Cite

@article{arxiv.1708.03987,
  title  = {The pure extension property for discrete crossed products},
  author = {Vrej Zarikian},
  journal= {arXiv preprint arXiv:1708.03987},
  year   = {2017}
}

Comments

A gap in the proof of the implication (iii => i) in Theorem 2.4 has been eliminated