English

Large Perturbations of Nest Algebras

Operator Algebras 2024-10-03 v2 Functional Analysis

Abstract

Let M\mathcal{M} and N\mathcal{N} be nests on separable Hilbert space. If the two nest algebras are distance less than 1 (d(T(M),T(N))<1d(\mathcal{T}(\mathcal{M}),\mathcal{T}(\mathcal{N})) < 1), then the nests are distance less than 1 (d(M,N)<1d(\mathcal{M},\mathcal{N})<1). If the nests are distance less than 1 apart, then the nest algebras are similar, i.e. there is an invertible SS such that SM=NS\mathcal{M} = \mathcal{N}, so that ST(M)S1=T(N)S \mathcal{T}(\mathcal{M})S^{-1} = \mathcal{T}(\mathcal{N}). However there are examples of nests closer than 1 for which the nest algebras are distance 1 apart.

Keywords

Cite

@article{arxiv.2408.03317,
  title  = {Large Perturbations of Nest Algebras},
  author = {Kenneth R. Davidson},
  journal= {arXiv preprint arXiv:2408.03317},
  year   = {2024}
}

Comments

Minor changes including a correction in the proof of Theorem 2.2. To appear in Integral Equations & Operator Theory