Resumen de Hosszú's equation over the Gaussian and Eisenstein integers

Gabriella Hajdu, Lajos Hajdu

• We consider Hosszú�s famous functional equation f(x) + f(y) = f(xy) + f(x + y - xy). We completely describe the set of functions satisfying this equation, where R is the set of the Gaussian or Eisenstein integers and is an arbitrary abelian group.