English

A continuous field of Roe algebras

Operator Algebras 2025-03-06 v3

Abstract

Let XX be a metric measure space. A Delone subset DXD\subset X is a uniformly discrete set coarsely equivalent to XX. We consider the space DF\mathcal D_F of controlled Delone subsets of XX with an appropriate metric, and show that it, together with XX itself, is a compact space. By assigning to each point DD of DF\mathcal D_F (resp., to XX) the uniform Roe algebra Cu(D)C^*_u(D) (resp., the \u Spakula's version Ck(X)C_k^*(X) of the Roe algebra of XX) we get a tautological family of CC^*-algebras. For a sequence {Dn}nN\{D_n\}_{n\in\mathbb N} of controlled Delone subsets convergent to XX we show that the corresponding uniform Roe algebras Cu(Dn)C^*_u(D_n), together with Ck(X)C^*_k(X), form a continuous field of CC^*-algebras over N{}\mathbb N\cup\{\infty\} when XX is a proper metric measure space of bounded geometry with no isolated points.

Keywords

Cite

@article{arxiv.2312.09363,
  title  = {A continuous field of Roe algebras},
  author = {V. Manuilov},
  journal= {arXiv preprint arXiv:2312.09363},
  year   = {2025}
}

Comments

11 pages, one of two main results of the previous version (about continuous fields) is generalized, and an error on the fiber at $\infty$ is fixed; another main result (about direct limits) does not allow a similar generalizations, so is skipped in the current version