English

Outer functions and divergence in de Branges-Rovnyak spaces

Complex Variables 2019-02-18 v1

Abstract

In most classical holomorphic function spaces on the unit disk in which the polynomials are dense, a function ff can be approximated in norm by its dilates fr(z):=f(rz) (r<1)f_r(z):=f(rz)~(r<1), in other words, limr1frf=0\lim_{r\to1^-}\|f_r-f\|=0. We construct a de Branges-Rovnyak space H(b){\mathcal H}(b) in which the polynomials are dense, and a function fH(b)f\in{\mathcal H}(b) such that limr1frH(b)=\lim_{r\to1^-}\|f_r\|_{{\mathcal H}(b)}=\infty. The essential feature of our construction lies in the fact that bb is an outer function.

Keywords

Cite

@article{arxiv.1902.05916,
  title  = {Outer functions and divergence in de Branges-Rovnyak spaces},
  author = {Javad Mashreghi and Thomas Ransford},
  journal= {arXiv preprint arXiv:1902.05916},
  year   = {2019}
}
R2 v1 2026-06-23T07:42:13.779Z