Let $M = (X, d)$ be a D1107: Metric space such that

(i)	$E, F \subseteq X$ are each a D78: Subset of $X$

The distance from $E$ to $F$ in $M$ is the D5237: Unsigned basic number \begin{equation} d(E, F) : = \inf \{ d(x, y) : x \in E, y \in F \} \end{equation}