English

On the small boundary property and $\mathcal Z$-absorption

Operator Algebras 2025-12-11 v2 Dynamical Systems

Abstract

We introduce the Property (C) for a unital commutative sub-C*-algebra DD of a unital C*-algebra AA, a version of the relative comparison property using almost normalizers. Under the assumption of this property, the Z\mathcal Z-absorption of AA is shown to imply the small boundary property of (D,T(A)D)(D, \mathrm{T}(A)|_D), where A=C(X)ZdA =\mathrm{C}(X) \rtimes \mathbb Z^d and D=C(X)D = \mathrm{C}(X).

Keywords

Cite

@article{arxiv.2504.03611,
  title  = {On the small boundary property and $\mathcal Z$-absorption},
  author = {George A. Elliott and Zhuang Niu},
  journal= {arXiv preprint arXiv:2504.03611},
  year   = {2025}
}

Comments

The original version contains a mistake in Section 3 on comparison using almost normalizers (Property (C)). In this revised version, Property (C) is used as the assumption, and we do not know if it holds for Jiang-Su absorbing C*-algebras

R2 v1 2026-06-28T22:47:08.271Z