
 PlanetMath: integer 
  is defined to be the set of equivalence classes of pairs of natural numbers 
  The ring of integers is also a Euclidean domain, with valuation given by the absolute value function. 
  Crossreferences: function, absolute value, valuation, Euclidean domain, ring of integers, ordered ring, ordering relation, integral domain, operations, representation, class, multiplication, addition, equivalence relation, equivalence classes, negatives, natural numbers 
 planetmath.org /encyclopedia/Integer.html (182 words) 
