# Closed

Revision as of 01:44, 24 December 2018 by Tom (talk | contribs) (Created page with "Let $(X,\tau)$ be a topological space. We say that $K \subset X$ is a closed set if its complement $X \setminus K \in \tau$. Category:Definition")

Let $(X,\tau)$ be a topological space. We say that $K \subset X$ is a closed set if its complement $X \setminus K \in \tau$.