\begin{definition}[Definition:Product Notation (Algebra)/Propositional Function/Iverson's Convention]
Let $\ds \prod_{\map R j} a_j$ be the product over all $a_j$ such that $j$ satisfies $R$.
This can also be expressed:
:$\ds \prod_{j \mathop \in \Z} a_j^{\sqbrk {\map R j} }$
where $\sqbrk {\map R j}$ is Iverson's convention.
\end{definition}