The 1954 Statelessness Status Convention provided a definition of a stateless person (which has since become part of customary international law, according to the International Law Commission), and sets out a number of rights that stateless persons should enjoy.
The ratio of two integers P and Q can be expressed as P : Q or P/Q. In both cases, you may divided P and Q by their greatest common factor so as to express the ratio in its simplest form.
An expression that is the ratio of two polynomials: It is just like a fraction, but with polynomials. A rational function is the ratio of two polynomials P(x) and Q(x) like this. Except that Q(x) cannot be zero (and anywhere that Q(x)=0 is undefined) A root (or zero) is where the expression is equal to zero: