English

Stable rank for inclusions of C*-algebras

Operator Algebras 2007-08-31 v1

Abstract

When a unital \ca AA has topological stable rank one (write \tsr(A)=1\tsr(A) = 1), we know that \tsr(pAp)1\tsr(pAp) \leq 1 for a non-zero projection pAp \in A. When, however, \tsr(A)2\tsr(A) \geq 2, it is generally faluse. We prove that if a unital C*-algebra AA has a simple unital C*-subalgebra DD of AA with common unit such that DD has \PSP and suppP(D)\tsr(pAp)<\sup_{p\in P(D)}\tsr(pAp) < \infty, then \tsr(A)2.\tsr(A) \leq 2. As an application let AA be a simple unital \ca with \tsr(A)=1\tsr(A) = 1 and \PSP, {Gk}k=1n\{G_k\}_{k=1}^n finite groups, \afk\af_k actions from GkG_k to Aut((...((A×\af1G1)×\af2G2)...)×\afk1Gk1).{\rm Aut}((...((A\times_{\af_1}G_1)\times_{\af_2} G_2)...)\times_{\af_{k-1}}G_{k-1}). (G0={1})(G_0 = \{1\}) Then \tsr((...((A×\af1G1)×\af2G2)...)×\afnGn)2. \tsr((... ((A\times_{\af_1}G_1)\times_{\af_2} G_2)...)\times_{\af_n}G_n) \leq 2.

Keywords

Cite

@article{arxiv.0708.4045,
  title  = {Stable rank for inclusions of C*-algebras},
  author = {Hiroyuki Osaka},
  journal= {arXiv preprint arXiv:0708.4045},
  year   = {2007}
}

Comments

9 pages