 (\langle x_{0},x_{0},x_{0}x_{0}^{0}\rangle,  \langle x_{0}x_{0}^{0}x_{0}^{0},x_{0}\rangle)$. Observe that $H=H_{0}\leq H_{0}\leq H_{0}=G$, where $H_{0}=\langle x_{0},x_{0},x_{0},x_{0}\rangle$, is a strong inductive chain