🌐EnglishEnglishDeutschEspañolFrançaisItalianoPolskiPortuguêsРусский한국어中文日本語EntityQ2119470· pop 15· linked from 37 articlesSierpiński spacefinite topological space with two points, only one of which is closedConnectionsnormal spaceEntitymetric spaceEntityCategoriesGeneral topologyTopological spaces