\begin{definition}[Definition:Closed Ball/Metric Space/Radius]
Let $M = \struct {A, d}$ be a metric space.
Let $a \in A$.
Let $\map { {B_\epsilon}^-} a$ be the closed $\epsilon$-ball of $a$.
The value $\epsilon$ is referred to as the '''radius''' of $\map { {B_\epsilon}^-} a$.
Category:Definitions/Metric Spaces
\end{definition}