English

Regular ideals, Ideal Intersections and Quotients II

Operator Algebras 2025-09-24 v1

Abstract

We continue the study of regular ideals in regular inclusions of C*-algebras. Let BAB \subseteq A be a regular inclusion of C*-algebras satisfying the ideal intersection property and with a faithful invariant pseudo-expectation. A complete description of the regular ideals of AA is given using the invariant regular ideals of BB and the pseudo-expectation. Further, necessary and sufficient conditions are given for a quotient by a regular ideal to preserve the faithful unique pseudo-expectation property. Special attention is given throughout to pseudo-Cartan inclusions, i.e. inclusions having a Cartan envelope. We show that the quotient of a pseudo-Cartan inclusion by a regular ideal is again a pseudo-Cartan inclusion, and we describe the Cartan envelope of the quotient.

Keywords

Cite

@article{arxiv.2509.19148,
  title  = {Regular ideals, Ideal Intersections and Quotients II},
  author = {Jonathan H. Brown and Adam H. Fuller and David R. Pitts and Sarah A. Reznikoff},
  journal= {arXiv preprint arXiv:2509.19148},
  year   = {2025}
}

Comments

20 pages

R2 v1 2026-07-01T05:52:21.364Z