$\left\{x\left|x\ge\frac{1}{2}\ ,\ x\in r\right|\right\}$

$\left\{x\left|x\le\frac{1}{2}\ ,\ x\in r\right|\right\}$

$\left\{x\left|x>\frac{1}{2}\ ,\ x\in r\right|\right\}$

$\left\{X\left|X<\frac{1}{2}\ ,\ X\in R\right|\right\}$