Cancellation for inclusions of C*-algebras of finite depth

Jeong, Ja A; Osaka, Hiroyuki; Phillips, N. Christopher; Teruya, Tamotsu

Cancellation for inclusions of C*-algebras of finite depth

Authors

Jeong, Ja A

Osaka, Hiroyuki

Phillips, N. Christopher

Teruya, Tamotsu

Description

Let B be a unital C*-algebra, let A be a unital subalgebra, and let E be a conditional expectation from B to A with index-finite type and a quasi-basis of n elements. Then the topological stable rank satisfies \tsr (B) \leq \tsr (A) + n - 1. As an application, we show that if a unital inclusion A \subset B of C*-algebras has index-finite type and finite depth, and A is simple with stable rank one and Property (SP), then B has cancellation. In particular, if A is a simple unital C*-algebra with stable rank one and Property (SP), and a finite group G acts on A, then the crossed product has cancellation. Separately, if the group is the integers, we obtain cancellation under the additional hypotheses that the group action is outer and is trivial on K_0 (A).
22 pages; AMSLaTeX