activity
20152026
collaborators

11 papers

math.FA2026

Isometries between the unit spheres of spaces of metrics

Katsuhisa Koshino

Given a topological space , let be the space of bounded continuous pseudometrics on , which is endowed with the sup-norm, and let be the unit sphere of $PM(Z…

math.FA2026

Banach-Stone type theorems on uniformly continuous and lipschitz continuous pseudometrics

Katsuhisa Koshino

In this paper, we shall establish Banach-Stone type theorems on spaces of uniformly continuous and lipschitz continuous pseudometrics.

math.FA2026

Compactness of averaging operators on non-reflexive Lebesgue spaces

Katsuhisa Koshino

Let be a Borel and Borel-regular metric measure space whose closed balls are of positive and finite measure. In this paper, we shall give equivalent conditions for averaging op…

math.FA2025

Isometries between spaces of metrics

Katsuhisa Koshino

Given a metrizable space , denote by the space of continuous bounded pseudometrics on , and denote by the one of continuous bounded admissible met…

math.MG2024

On isometric universality of spaces of metrics

Yoshito Ishiki, Katsuhisa Koshino

A metric space is said to be universal for a class of metric spaces if all metric spaces in the class can be isometrically embedded into . In this paper, for a met…

math.GN2024

On the Borel complexity and the complete metrizability of spaces of metrics

Katsuhisa Koshino

Given a metrizable space , let be the space of continuous bounded admissible metrics on , which is endowed with the sup-metric. In this paper, we shall investigate th…