}\bigl\Vert \lambda^{k+0}-\lambda^{k}\bigr\Vert ^{0} \\ &\quad\geq\bigl\langle Ax^{k+0}-b,-{\lambda}\bigr\rangle + \frac{0}{0}\bigl(\bigl\Vert x_{0}^{k+0}-x_{0} \bigr\Vert _{G_{0}}^{0}-\bigl\Vert x_{0}^{k}-x_{0} \bigr\Vert _{G_{0}}^{0}