English

On anti-coproximinal and strongly anti-coproximinal subspaces of function spaces

Functional Analysis 2026-02-02 v2

Abstract

The purpose of this article is to study the anti-coproximinal and strongly anti-coproximinal subspaces of the Banach space of all bounded (continuous) functions. We obtain a tractable necessary condition for a subspace to be stronsgly anti-coproximinal. We prove that for a subspace Y\mathbb{Y} of a Banach space X\mathbb{X} to be strongly anti-coproximinal, Y\mathbb Y must contain all w-ALUR points of X\mathbb{X} and intersect every maximal face of BX.B_{\mathbb{X}}. We also observe that the subspace K(X,Y)\mathbb{K}(\mathbb{X}, \mathbb{Y}) of all compact operators between the Banach spaces X \mathbb X and Y \mathbb Y is strongly anti-coproximinal in the space L(X,Y)\mathbb{L}(\mathbb{X}, \mathbb{Y}) of all bounded linear operators between X \mathbb X and Y \mathbb Y, whenever K(X,Y)\mathbb{K}(\mathbb{X}, \mathbb{Y}) is a proper subset of L(X,Y),\mathbb{L}(\mathbb{X}, \mathbb{Y}), and the unit ball BXB_{\mathbb{X}} is the closed convex hull of its strongly exposed points.

Keywords

Cite

@article{arxiv.2504.13464,
  title  = {On anti-coproximinal and strongly anti-coproximinal subspaces of function spaces},
  author = {Shamim Sohel and Souvik Ghosh and Debmalya Sain and Kallol Paul},
  journal= {arXiv preprint arXiv:2504.13464},
  year   = {2026}
}