🌐EnglishEnglishDeutschEspañolFrançaisItalianoNederlandsPolskiPortuguêsTiếng ViệtРусскийالعربيةفارسی한국어中文日本語EntityQ331481· pop 27· linked from 160 articlescoverfamily of subsets of a set whose union equals the whole setAvailable in 27 languagesEspañolFrançaisDeutsch中文日本語РусскийPortuguêsItalianoالعربيةCatalanConnectionsmathematicsEntityInternational Standard Book NumberEntityCategoriesFamilies of setsGeneral topologyTopology