A Universal Separable Diversity

The Urysohn space is a separable complete metric space with two fundamental properties: (a) universality: every separable metric space can be isometrically embedded in it; (b) ultrahomogeneity: every finite isometry between two finite subspaces can be extended to an auto-isometry of the whole space....

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Autores principales: Bryant David, Nies André, Tupper Paul
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Lenguaje:EN
Publicado: De Gruyter 2017
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Acceso en línea:https://doaj.org/article/f8be5f5af176464ebff761d35c410a9d
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spelling oai:doaj.org-article:f8be5f5af176464ebff761d35c410a9d2021-12-05T14:10:38ZA Universal Separable Diversity2299-327410.1515/agms-2017-0008https://doaj.org/article/f8be5f5af176464ebff761d35c410a9d2017-12-01T00:00:00Zhttps://doi.org/10.1515/agms-2017-0008https://doaj.org/toc/2299-3274The Urysohn space is a separable complete metric space with two fundamental properties: (a) universality: every separable metric space can be isometrically embedded in it; (b) ultrahomogeneity: every finite isometry between two finite subspaces can be extended to an auto-isometry of the whole space. The Urysohn space is uniquely determined up to isometry within separable metric spaces by these two properties. We introduce an analogue of the Urysohn space for diversities, a recently developed variant of the concept of a metric space. In a diversity any finite set of points is assigned a non-negative value, extending the notion of a metric which only applies to unordered pairs of points.We construct the unique separable complete diversity that it is ultrahomogeneous and universal with respect to separable diversities.Bryant DavidNies AndréTupper PaulDe Gruyterarticlediversitiesurysohn spacekatetov functionsuniversalityultrahomogeneity51f9954e5054e99AnalysisQA299.6-433ENAnalysis and Geometry in Metric Spaces, Vol 5, Iss 1, Pp 138-151 (2017)
institution DOAJ
collection DOAJ
language EN
topic diversities
urysohn space
katetov functions
universality
ultrahomogeneity
51f99
54e50
54e99
Analysis
QA299.6-433
spellingShingle diversities
urysohn space
katetov functions
universality
ultrahomogeneity
51f99
54e50
54e99
Analysis
QA299.6-433
Bryant David
Nies André
Tupper Paul
A Universal Separable Diversity
description The Urysohn space is a separable complete metric space with two fundamental properties: (a) universality: every separable metric space can be isometrically embedded in it; (b) ultrahomogeneity: every finite isometry between two finite subspaces can be extended to an auto-isometry of the whole space. The Urysohn space is uniquely determined up to isometry within separable metric spaces by these two properties. We introduce an analogue of the Urysohn space for diversities, a recently developed variant of the concept of a metric space. In a diversity any finite set of points is assigned a non-negative value, extending the notion of a metric which only applies to unordered pairs of points.We construct the unique separable complete diversity that it is ultrahomogeneous and universal with respect to separable diversities.
format article
author Bryant David
Nies André
Tupper Paul
author_facet Bryant David
Nies André
Tupper Paul
author_sort Bryant David
title A Universal Separable Diversity
title_short A Universal Separable Diversity
title_full A Universal Separable Diversity
title_fullStr A Universal Separable Diversity
title_full_unstemmed A Universal Separable Diversity
title_sort universal separable diversity
publisher De Gruyter
publishDate 2017
url https://doaj.org/article/f8be5f5af176464ebff761d35c410a9d
work_keys_str_mv AT bryantdavid auniversalseparablediversity
AT niesandre auniversalseparablediversity
AT tupperpaul auniversalseparablediversity
AT bryantdavid universalseparablediversity
AT niesandre universalseparablediversity
AT tupperpaul universalseparablediversity
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