English

Hilbert points in Hilbert space-valued $L^p$ spaces

Functional Analysis 2023-02-28 v1

Abstract

Let HH be a Hilbert space and (Ω,F,μ)(\Omega,\mathcal{F},\mu) a probability space. A Hilbert point in Lp(Ω;H)L^p(\Omega; H) is a nontrivial function φ\varphi such that φpφ+fp\|\varphi\|_p \leq \|\varphi+f\|_p whenever f,φ=0\langle f, \varphi \rangle = 0. We demonstrate that φ\varphi is a Hilbert point in Lp(Ω;H)L^p(\Omega; H) for some p2p\neq2 if and only if φ(ω)H\|\varphi(\omega)\|_H assumes only the two values 00 and C>0C>0. We also obtain a geometric description of when a sum of independent Rademacher variables is a Hilbert point.

Keywords

Cite

@article{arxiv.2202.11373,
  title  = {Hilbert points in Hilbert space-valued $L^p$ spaces},
  author = {Ole Fredrik Brevig and Sigrid Grepstad},
  journal= {arXiv preprint arXiv:2202.11373},
  year   = {2023}
}
R2 v1 2026-06-24T09:50:48.755Z