English

Essentially Commuting with a Unitary

Functional Analysis 2025-01-08 v1 Mathematical Physics math.MP Operator Algebras

Abstract

Let RR be a unitary operator whose spectrum is the circle. We show that the set of unitaries UU which essentially commute with RR (i.e., [U,R]URRU[U,R]\equiv UR-RU is compact) is path-connected. Moreover, we also calculate the set of path-connected components of the orthogonal projections which essentially commute with RR and obey a non-triviality condition, and prove it is bijective with Z\mathbb{Z}.

Cite

@article{arxiv.2501.03934,
  title  = {Essentially Commuting with a Unitary},
  author = {Jui-Hui Chung and Jacob Shapiro},
  journal= {arXiv preprint arXiv:2501.03934},
  year   = {2025}
}
R2 v1 2026-06-28T20:58:57.903Z