English

On the Ball Covering Property of $\mathbb{L}(\mathbb{X}, \mathbb{Y})$

Functional Analysis 2026-07-11 v1

Abstract

We investigate the Ball Covering Property (BCP) of Banach spaces through the lens of Birkhoff-James orthogonality, yielding a new geometric characterization of the property. Applying this framework, we characterize the BCP of the bounded linear operator space L(X,Y)\mathbb{L}(\mathbb{X}, \mathbb{Y}) under specific conditions on X\mathbb{X} and Y\mathbb{Y}, proving that an earlier necessary condition is sufficient. As an application, we provide a complete affirmative answer to an open question concerning the BCP of L(Lp[0,1])\mathbb{L}(L^p[0,1]). We also establish the stability of the BCP under pp-norm direct sums. In finite dimensions, we provide a sufficient condition for an nn-dimensional Banach space to have a minimal covering by n+1n+1 balls. Furthermore, we find an upper bound for the minimal ball covering number of L(X,Y)\mathbb{L}(\mathbb{X}, \mathbb{Y}) in the finite-dimensional setting and prove that this number is exactly mn+1mn+1 when X\mathbb{X} is an mm-dimensional strictly convex space and Y\mathbb{Y} is an nn-dimensional smooth space.

Keywords

Cite

@article{arxiv.2607.10353,
  title  = {On the Ball Covering Property of $\mathbb{L}(\mathbb{X}, \mathbb{Y})$},
  author = {Ankan Mishra and Kallol Paul and Debmalya Sain and Shamim Sohel},
  journal= {arXiv preprint arXiv:2607.10353},
  year   = {2026}
}