English

A study on various generalizations of Generalized centers $\bm{(GC)}$ in Banach spaces

Functional Analysis 2024-10-22 v2 Optimization and Control

Abstract

In [{\em Generalized centers of finite sets in Banach spaces}, Acta Math. Univ. Comenian. (N.S.) {\bf 66}(1) (1997), 83--115], Vesel\'{y} developed the idea of generalized centers for finite sets in Banach spaces. In this work, we explore the concept of {\it restricted \mrF\mr{F}-center property} for a triplet (X,Y,\mcF(X))(X,Y,\mc{F}(X)), where YY is a subspace of a Banach space XX and \mcF(X)\mc{F}(X) is the family of finite subsets of XX. In addition, we generalize the analysis to include all closed, bounded subsets of XX. Similar to how Lindenstrauss characterized n.2.I.P.n.2.I.P., we characterize n.X.I.P.n.X.I.P.. So, it is possible to figure out that YY has n.X.I.P.n.X.I.P. in XX for all natural numbers nn if and only if \trradY(F)=\trradX(F)\tr{rad}_Y(F)=\tr{rad}_X(F) for all finite subsets FF of YY. It then turns out that, for all continuous, monotone functions ff, the ff-radii viz. \trradYf(F),\trradXf(F)\tr{rad}_Y^f(F),\tr{rad}_X^f(F) are same whenever the generalized radii viz. \trradY(F),\trradX(F)\tr{rad}_Y(F), \tr{rad}_X(F) are also same, for all finite subsets FF of YY. We establish a variety of characterizations of central subspaces of Banach spaces. With reference to an appropriate subfamily of closed and bounded subsets, it appears that a number of function spaces and subspaces exhibit the restricted weighted Chebyshev center property.

Keywords

Cite

@article{arxiv.2311.15818,
  title  = {A study on various generalizations of Generalized centers $\bm{(GC)}$ in Banach spaces},
  author = {Syamantak Das and Tanmoy Paul},
  journal= {arXiv preprint arXiv:2311.15818},
  year   = {2024}
}