The set of Positive Rationals is defined as the set of numbers that can be written as a fraction
of two integers and are non-negative, i.e.
$$NegRationals = \{\frac{p}{q} | p,q \ \in \ Z, \ \frac{p}{q} \le 0\}$$
where \(Z\) is the set of integers.
\(0\) may or may not be included (depending on the zero
argument).