English

Hilbert space models and Blaschke frames

Functional Analysis 2025-10-24 v2 Complex Variables

Abstract

For a finite Blaschke product BB and for an isometry VV on an infinite-dimensional separable complex Hilbert space H\mathcal{H} we study a sequence (bm)m=1(b_m)_{m=1}^\infty of vectors in H\mathcal{H}, defined by bm=B(V)emb_m = B(V^*)e_m, where (em)m=1(e_m)_{m=1}^\infty is an orthonormal basis in H\mathcal{H}. We call (bm)m=1(b_m)_{m=1}^\infty a Blaschke frame for BB with isometry VV on H\mathcal{H}. We show how instrumental the use of Hilbert space models are in frame theory by completely solving the question of redundancy for a Blaschke frame, that is, what vectors can be removed from the frame (bm)m=1(b_{m})_{m=1}^{\infty} such that (bm)mk(b_{m})_{m\neq k} is still a frame? Using the Wold decomposition, we prove that a Blaschke frame can have no redundant vectors (a Riesz basis), have some redundant vectors, or every vector is redundant (a fully insured frame). These unique cases depend on the choice of finite Blaschke product and which isometry one chooses in the construction of a Blaschke frame.

Keywords

Cite

@article{arxiv.2510.18816,
  title  = {Hilbert space models and Blaschke frames},
  author = {Connor Evans},
  journal= {arXiv preprint arXiv:2510.18816},
  year   = {2025}
}

Comments

22 pages

R2 v1 2026-07-01T06:58:14.783Z