Resumen de On the functional equation x + f(y + f(x)) = y + f(x + f(y))
We present some properties of solutions of the equation where f is a self-mapping of an abelian group. Among others we prove that if such a solution f vanishes at 0 then 2f is additive. Using this we solve the equation in the class of self�mappings of the complex plane continuous at a point.
