🌐EnglishEnglishDeutschEspañolFrançaisNederlandsPolskiРусский日本語EntityQ2064647· pop 13· linked from 25 articlesring of setsSet closed under union and intersectionAvailable in 13 languagesEspañolFrançaisDeutsch日本語РусскийCatalanChuvashHebrewIdoNederlandsPolskiConnectionstopological spaceEntitymeasureEntityCategoriesFamilies of setsMeasure theory