Angles Between Intermediate Operator Subalgebras
Operator Algebras
2026-02-04 v1
Abstract
Motivated by [2] and [5], the notions of interior and exterior angles between a pair of compatible intermediate W*-subalgebras of an inclusion of W*-algebras with a normal conditional expectation with finite probabilistic index are introduced. This is then employed effectively to define the interior angle between a pair of compatible intermediate C*-subalgebras of an inclusion of non-unital C*-algebras with a conditional expectation with finite Watatani index. It is also shown that the interior angle is stable under the minimal tensor product of unital C*-algebras.
Keywords
Cite
@article{arxiv.2602.03694,
title = {Angles Between Intermediate Operator Subalgebras},
author = {Ved Prakash Gupta and Deepika Sharma},
journal= {arXiv preprint arXiv:2602.03694},
year = {2026}
}