\begin{definition}[Definition:Ordered Pair/Notation]
In the field of symbolic logic and modern treatments of set theory, the notation $\sequence {a, b}$ is often seen to denote an '''ordered pair'''.
In sources where the possibility of confusion is only minor, one can encounter $a \times b$ for $\tuple {a, b}$ on an ad hoc basis.
These notations are not used on {{ProofWiki}}, where $\tuple {a, b}$ is used exclusively.
\end{definition}