figure. Moreover, one also finds that the mastercurves $g(x)$ are numerically indistinguishable for different $p$, and they all coincide with that of Eq. (\[struttising\]). This result is trivial for $p=4$, since in this case the clock model can be mapped exactly on two non-interacting Ising models. The same property could be expected also for $p=3$. In fact, by considering $G(r,t)$, it easy (see Appendix) to check that G(r,t)=G\_P(r,t)-, \[maj1\] where $G_P(r,t)$ is the [*single phase* ]{} equal time correlation function of the 3-state Potts model. This quantity was computed in [@Sire], where it was found G\_P(r,t)=G\_I(r,t)+, \[maj2\] where $G_I(r,t)$ is the equal time correlation function of the Ising model. Plugging Eq. (\[maj2\]) into Eq. (\[maj1\]) one finds $G(r,t)=G_I(r,t)$. The same argument shows also the identity between the two time correlation functions of the clock model with $p=3$ and the Ising model, strongly suggesting the complete equivalence between these models.

Let us emphasize that this result indicates a stronger similarity among the cases $p=2,3,4$ than a unique non-equilibrium universality class would imply, since not only the exponents are equal but the whole functional form of the scaling function. This results are in contrast with those of ref. [@Liu93] where an approximate 