English

Geometrically regular weighted shifts

Functional Analysis 2026-05-12 v2

Abstract

We study a general class of weighted shifts whose weights α\alpha are given by αn=pn+Npn+D\alpha_n = \sqrt{\frac{p^n + N}{p^n + D}}, where p>1p > 1 and NN and DD are parameters so that (N,D)(1,1)×(1,1)(N,D) \in (-1, 1)\times (-1, 1). Some few examples of these shifts have appeared previously, usually as examples in connection with some property related to subnormality. In sectors nicely arranged in the unit square in (N,D)(N,D), we prove that these geometrically regular weighted shifts exhibit a wide variety of properties: moment infinitely divisible, subnormal, kk- but not (k+1)(k+1)-hyponormal, or completely hyperexpansive, and with a variety of well-known functions (such as Bernstein functions) interpolating their weights squared or their moment sequences. They provide subshifts of the Bergman shift with geometric, not linear, spacing in the weights which are moment infinitely divisible. This new family of weighted shifts provides a useful addition to the library of shifts with which to explore new definitions and properties.

Keywords

Cite

@article{arxiv.2309.05888,
  title  = {Geometrically regular weighted shifts},
  author = {Chafiq Benhida and Raul E. Curto and George R. Exner},
  journal= {arXiv preprint arXiv:2309.05888},
  year   = {2026}
}
R2 v1 2026-06-28T12:18:44.366Z