Hausdorff distance between ultrametric balls




Dovgoshey, Oleksiy

PublisherSpringer Nature Switzerland AG

2025

 Journal of Mathematical Sciences

1072-3374

1573-8795

DOIhttps://doi.org/10.1007/s10958-025-08125-0

https://doi.org/10.1007/s10958-025-08125-0

https://arxiv.org/abs/2509.00205



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



The author was supported by grant 359772 of the Academy of Finland.


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