Proper

A proper system has the following properties

$$h(s)=\frac{n(s)}{d(s)}\to deg(d(s))\ge deg(n(s))$$

and

$$|h_p(j\infty )|<\infty ,\cap |h_{sp}(j\infty )|=0$$

Meaning that the following function is proper:

$$h(s)=\frac{s+1}{s^2-2s+1}$$