🌐EnglishEnglishDeutschEspañolFrançaisItalianoNederlandsPolskiPortuguêsSvenskaTiếng ViệtРусскийالعربيةفارسی한국어中文日本語EntityQ1816967· pop 19· linked from 109 articlesUrysohn's lemmalemma that a topological space is normal iff any 2 disjoint closed subsets can be separated by a continuous functionWikidata factsImageUrysohn-function01.svgSources (1)wikidata.orgvia Wikidata · CC0Available in 18 languagesEspañolFrançaisDeutsch中文РусскийPortuguêsItalianoCatalanFinnishHebrewNederlandsConnectionscontinuous functionEntityseparated setsEntityCategoriesLemmasSeparation axiomsTheorems in topologyTheory of continuous functions