\begin{definition}[Definition:Commutative/Operation]
Let $\struct {S, \circ}$ be an algebraic structure.
Then $\circ$ is '''commutative on $S$''' {{iff}}:
:$\forall x, y \in S: x \circ y = y \circ x$
That is, if every pair of elements of $S$ commutes.
\end{definition}