Classification of equivariantly ${\mathcal{O}}_2$-stable amenable actions on nuclear ${\mathrm{C}}^{\ast }$-algebras

Abstract

Given a second-countable, locally compact group $G$, we consider amenable $G$-actions on separable, stable, nuclear ${\mathrm{C}}^{\ast }$-algebras that are isometrically shift-absorbing and tensorially absorb the trivial action on the Cuntz algebra ${\mathcal{O}}_2$. We show that such actions are classified up to cocycle conjugacy by the induced $G$-action on the primitive ideal space. In the special case when $G$ is exact, we prove a unital version of our classification theorem. For compact groups, we obtain a classification up to conjugacy.

39 pages; v3 some corrections; this version is accepted for publication at JFA