🌐EnglishEnglishDeutschFrançaisPolskiPortuguêsРусский中文日本語EntityQ4392123· pop 8· linked from 25 articlesFσ setcountable union of closed setsAvailable in 8 languagesFrançaisDeutsch中文日本語РусскийPolskiUkrainianvia Wikidata sitelinks · CC0ConnectionsGδ setEntityFrenchEntityCategoriesDescriptive set theoryGeneral topology