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A note on the quasi-local algebra of expander graphs

Operator Algebras 2025-11-25 v2 Functional Analysis

Abstract

We show that the quasi-local algebra of a coarse disjoint union of expander graphs does not contain a Cartan subalgebra isomorphic to \ell_\infty. N. Ozawa has recently shown that these algebras are distinct from the uniform Roe algebras of expander graphs, and our result describes a further difference.

Keywords

Cite

@article{arxiv.2508.07327,
  title  = {A note on the quasi-local algebra of expander graphs},
  author = {Bruno M. Braga and Ján Špakula and Alessandro Vignati},
  journal= {arXiv preprint arXiv:2508.07327},
  year   = {2025}
}

Comments

14 pages, minor corrections and updates