# Compact Complement Topology is Compact

## Theorem

Let $T = \struct {\R, \tau}$ be the compact complement topology on $\R$.

Then $T$ is a compact space.

## Proof

Let $\CC$ be an open cover of $\R$.

Let $U \in \CC$.

Then by definition $\R \setminus U$ is compact in the usual (Euclidean) topology.

Since each $U$ is open in the Euclidean topology, a finite number must cover $\R \setminus U$.

$\blacksquare$