Urysohn's lemma

proper noun

A lemma stating that a topological space is normal if and only if any two disjoint closed subsets can be separated by a continuous function.

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Meanings

proper noun
  1. mathematicsA lemma stating that a topological space is normal if and only if any two disjoint closed subsets can be separated by a continuous function.

Origin

Named after the mathematician Pavel Samuilovich Urysohn.

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Cite this entry
APA

Urysohn's lemma. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/Urysohn's%20lemma

MLA

“Urysohn's lemma.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Urysohn's%20lemma. Accessed November 5, 2026.

Chicago

WatkinsX Dictionary, s.v. “Urysohn's lemma,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/Urysohn's%20lemma.

Source: Urysohn's lemma on Wiktionary, CC BY-SA 4.0.