\begin{definition}[Definition:Dirac Delta Function/2 Dimensional]
Let $\delta: \R \to \R$ denote the '''Dirac delta function'''.
The $2$-dimensional form of $\delta$ is defined and denoted:
:$\forall x, y \in \R: \map { {}^2 \delta} {x, y} := \map \delta x \map \delta y$
\end{definition}