Definition:Half-Plane/Open/Left

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

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

The open left half-plane $H_{\text {OL} }$ is the area of $P$ on the left of $L$.

That is, where $x < 0$:


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

Also see

 * Definition:Open Right Half-Plane


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


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


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