Certain aperiodic automorphisms of unital simple projectionless C*-algebras

摘要

Let $G$ be an inductive limit of finite cyclic groups and let $A$ be a unitalsimple projectionless C*-algebra with $K_1(A) \cong G$ and with a uniquetracial state, as constructed based on dimension drop algebras by Jiang and Su.First, we show that any two aperiodic elements in $\Aut(A)/\WInn(A)$ areconjugate, where $\WInn(A)$ means the subgroup of $\Aut(A)$ consisting ofautomorphisms which are inner in the tracial representation. In the second part of this paper, we consider a class of unital simpleC*-algebras with a unique tracial state which contains the class of unitalsimple AT-algebras of real rank zero with a unique tracial state. This class isclosed under inductive limits and under crossed products by actions of $\Z$with the Rohlin property. Let $A$ be a TAF-algebra in this class. We show thatfor any automorphism $\alpha$ of $A$ there exists an automorphism$\widetilde{\alpha}$ of $A$ with the Rohlin property such that$\widetilde{\alpha}$ and $\alpha$ are asymptotically unitarily equivalent. Inits proof we use an aperiodic automorphism of the Jiang-Su algebra.