English

Some sufficient conditions for existence of hyperinvariant subspaces for operators intertwined with unitaries

Functional Analysis 2018-12-28 v2

Abstract

For a power bounded or polynomially bounded operator TT sufficient conditions for the existence of a nontrivial hyperinvariant subspace are given. The obtained hyperinvariant subspaces of TT have the form of the closure of the range of φ(T)\varphi(T). Here φ\varphi is a singular inner function, if TT is polynomially bounded, or φ\varphi is an analytic in the unit disc function with absolutely summable Taylor coefficients and singular inner part, if TT is supposed to be power bounded only. Also, an example of a quasianalytic contraction TT is given. The quasianalytic spectral set of TT is not the whole unit circle T\mathbb T, while σ(T)=T\sigma(T)=\mathbb T. Proofs are based on results by Esterle, Kellay, Borichev and Volberg.

Keywords

Cite

@article{arxiv.1712.07075,
  title  = {Some sufficient conditions for existence of hyperinvariant subspaces for operators intertwined with unitaries},
  author = {Maria F. Gamal'},
  journal= {arXiv preprint arXiv:1712.07075},
  year   = {2018}
}

Comments

This is Studia Math., 246(2019), 133-166 enlarged in the following sense: all proofs of lemmas deleted are preserved here