English

Hausdorff distance between ultrametric balls

General Topology 2025-09-03 v1

Abstract

Let (X,d)(X, d) be an ultrametric space and let dHd_H be the Hausdorff distance on the set BˉX\bar{\mathbf{B}}_X of all closed balls in (X,d)(X, d). Some interconnections between the properties of the spaces (X,d)(X, d) and (BˉX,dH)(\bar{\mathbf{B}}_X, d_H) are described. It is established that the space (BˉX,dH)(\bar{\mathbf{B}}_X, d_H) has such properties as discreteness, local finiteness, metrical discreteness, completeness, compactness, local compactness if and only if the space (X,d)(X, d) has these properties. Necessary and sufficient conditions for the separability of the space (BˉX,dH)(\bar{\mathbf{B}}_X, d_H) are also proved.

Keywords

Cite

@article{arxiv.2509.00205,
  title  = {Hausdorff distance between ultrametric balls},
  author = {Oleksiy Dovgoshey},
  journal= {arXiv preprint arXiv:2509.00205},
  year   = {2025}
}

Comments

28 pages

R2 v1 2026-07-01T05:12:59.081Z