Ambiguities and symmetry relations in the perturbative solution of quantumelectrodynamics

We show that ambiguities and symmetry violations arising in one loop calcul ations can always be avoided provided the regularization scheme employed sa tisfies three consistency conditions. Our calculations are effected by assu ming only implicitly the presence of a regulator in the integrand. We demon strate in this way that there is a set of three relations involving diverge nt integrals of the same degree of divergence which are the source of both ambiguities and symmetry violations in Quantum Electrodynamics. Moreover we give analytical expressions for the finite parts of amplitudes off the mas s shell systematized in terms of a set of special functions. Ward identitie s require hightly nom trivial relations involving those functions which we also derive.