Normal Spaces via Urysohn's Lemma as a Lifting Property

Robert Maxton

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arXiv · 2602.11178

Normal Spaces via Urysohn's Lemma as a Lifting Property

Robert Maxton

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Abstract

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.

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Robert Maxton. 2026-01-21. Normal Spaces via Urysohn's Lemma as a Lifting Property. https://arxiv.org/abs/2602.11178

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