Definition:Half-Plane/Closed/Upper

Definition
Let $P$ denote the plane implemented as a Cartesian system.

Let $L$ be the $x$-axis.

The closed upper half-plane $H_{\text {CU} }$ is the area of $P$ above and including $L$.

That is, where $y \ge 0$:


 * $H_{\text {CU} } := \set {\tuple {x, y}: y \in \R_{\ge 0} }$

Also see

 * Definition:Closed Lower Half-Plane


 * Definition:Closed Left Half-Plane
 * Definition:Closed Right Half-Plane


 * Definition:Open Upper Half-Plane
 * Definition:Open Lower Half-Plane


 * Definition:Open Right Half-Plane
 * Definition:Open Left Half-Plane