Figure 2

Diamond-tangent line at the isolated point of the curve α . Therefore, \(\gamma(t_{0})=\frac{\sigma(t_{0})-t_{0}}{\sigma(t_{0})-\rho(t_{0})}\), and \(\alpha^{\Diamond}(t_{0}) = \frac{\sigma(t_{0})-t_{0}}{\sigma(t_{0})-\rho(t_{0})} \alpha^{\Delta}(t_{0})+\frac{t_{0}-\rho(t_{0})}{\sigma(t_{0}) -\rho(t_{0})}\alpha^{\nabla}(t_{0})\).