Zamolodchikov and Cardy have shown that the minimal unitary theory with central charge $c=1-\frac{6}{p(p+1)}$ changes into the minimal unitary theory with central charge $c=1-\frac{6}{p(p+1)}$ in the perturbation by $\phi_{13}$. And Zamolodchikov argued that with perturbation by $\phi_{31}$ one might get the reverse result. In this thesis we show this really occurs.