## Errata

• Definition 7.2 contains a typo. The correct version is below.

Let $$X$$ be a metric space with metric $$d$$ and suppose $$U,\, V \subset X.$$ A set $$U$$ is dense in a set $$V$$ if for every $$\epsilon>0$$ and every point $$v \in V$$, there exists a $$u \in U$$ such that $$d(u,v)< \epsilon$$.