English

Analytic $m$-isometries without the wandering subspace property

Functional Analysis 2019-04-02 v2

Abstract

The wandering subspace problem for an analytic norm-increasing mm-isometry TT on a Hilbert space H\mathcal H asks whether every TT-invariant subspace of H\mathcal H can be generated by a wandering subspace. An affirmative solution to this problem for m=1m=1 is ascribed to Beurling-Lax-Halmos, while that for m=2m=2 is due to Richter. In this paper, we capitalize on the idea of weighted shift on one-circuit directed graph to construct a family of analytic cyclic 33-isometries, which do not admit the wandering subspace property and which are norm-increasing on the orthogonal complement of a one-dimensional space. Further, on this one dimensional space, their norms can be made arbitrarily close to 11. We also show that if the wandering subspace property fails for an analytic norm-increasing mm-isometry, then it fails miserably in the sense that the smallest TT-invariant subspace generated by the wandering subspace is of infinite codimension.

Keywords

Cite

@article{arxiv.1811.12080,
  title  = {Analytic $m$-isometries without the wandering subspace property},
  author = {Akash Anand and Sameer Chavan and Shailesh Trivedi},
  journal= {arXiv preprint arXiv:1811.12080},
  year   = {2019}
}

Comments

14 pages, 2 figures, major revision, Section 4 is added

R2 v1 2026-06-23T06:24:56.649Z