Normal Spaces via Urysohn's Lemma as a Lifting Property

Fuente: arXiv
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Autor principal: Maxton, Robert
Formato: Preprint
Publicado: 2026
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author Maxton, Robert
author_facet Maxton, Robert
contents We present a translation of Urysohn's description of normal spaces (as those where disjoint closed subsets are separated by a continuous function) into the language of lifting properties in $\mathbf{Top}$, correcting a frequently-cited previous erroneous translation. We also present a translation of the definition of hereditarily normal spaces as those in which every open subspace is normal, by directly 'mapping' the translation of the usual description of normal spaces.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11178
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Normal Spaces via Urysohn's Lemma as a Lifting Property
Maxton, Robert
General Topology
54D15 (Primary) 18A20, 54B30 (Secondary)
We present a translation of Urysohn's description of normal spaces (as those where disjoint closed subsets are separated by a continuous function) into the language of lifting properties in $\mathbf{Top}$, correcting a frequently-cited previous erroneous translation. We also present a translation of the definition of hereditarily normal spaces as those in which every open subspace is normal, by directly 'mapping' the translation of the usual description of normal spaces.
title Normal Spaces via Urysohn's Lemma as a Lifting Property
topic General Topology
54D15 (Primary) 18A20, 54B30 (Secondary)
url https://arxiv.org/abs/2602.11178