Source: wikibot/clopen-set
= Clopen set
{wiki=Clopen_set}
In topology, a set is called **clopen** if it is both **closed** and **open**. To understand this concept, we need to clarify what it means for a set to be open and closed: 1. A set \\( U \\) in a topological space is **open** if, for every point \\( x \\) in \\( U \\), there exists a neighborhood of \\( x \\) that is entirely contained within \\( U \\).