An irreducible fraction is a fraction for which , i.e., and are relatively prime. For example, in the complex plane, is reducible, while is not.
The figure above shows the irreducible fractions plotted in the complex plane (Pickover 1997; Trott 2004, p. 29).
for which 
, i.e., 
and 
are relatively prime. For example, in the complex plane, 
is reducible, while 
is not.