Resolução de problema via inteiros algébricos

Abstract

In this paper, we present the definitions of integral domain, euclidean domain, principal ideal domain and unique factorization domain and we prove the implications Euclidean Domain ⇒ Principal Ideal Domain ⇒ Unique Factorization Domain. We check that the set of Gaussian integers is a unique factorization domain, we find its prime elements and we describe several properties of this set, applying them especially to describe, completely, the Pythagorean triples and to calculate the number of ways one can write an integer as a sum of two squares. We also check that the set of Eisenstein integers is a unique factorization domain, we also find its prime elements and we apply the properties of this set to describe the general form of a triple of integers that are sides of a triangle with an angle of 60 o . We present the general form of the integers of Q [√d] and, for d < 0, we exhibit all values of d for which this ring a unique factorization domain. Lastly, we apply the developed theory to solve several problems of mathematical olympiads.