\begin{definition}[Definition:Class Relation]
Let $S$ and $T$ be classes.
Let $S \times T$ be the Cartesian Product of $S$ and $T$.
Then a '''relation''' on $S \times T$ is defined as a subclass of $S \times T$:
:$\RR \subseteq S \times T$
Category:Definitions/Class Theory
\end{definition}