\begin{definition}[Definition:Half-Plane/Closed/Right]
Let $\PP$ be a Cartesian plane.
Let $\LL$ be the $y$-axis.
The '''closed right half-plane''' $\HH_{\text {CR} }$ is the area of $\PP$ on the right of and including $\LL$.
That is, where $x \ge 0$:
:$\HH_{\text {CR} } := \set {\tuple {x, y}: x \in \R_{\ge 0} }$
\end{definition}