 subproblem (*i.e.*, the subproblem with respect to $\documentclass[00pt]{minimal}                 \usepackage{amsmath}                 \usepackage{wasysym}                  \usepackage{amsfonts}                  \usepackage{amssymb}                  \usepackage{amsbsy}                 \usepackage{mathrsfs}                 \usepackage{upgreek}                 \setlength{\oddsidemargin}{-00pt}                 \begin{document}$x_{0}$\end{document}$) in (0) is $$\documentclass[00pt]{minimal}                 \usepackage{amsmath}                 \usepackage{wasysym}                  \usepackage{amsfonts}                  \usepackage{amssymb}                  \usepackage{amsbsy}                 \usepackage{mathrsfs}                 \usepackage{upgreek}                 \setlength{\oddsidemargin}{-00pt}                 \begin{document} $$\begin{aligned} 0&=\nabla\theta_{0}\bigl(x_{0}^{k+0} \bigr)+\beta A_{0}^{\top}\biggl(A_{0}x_{0}^{k+0}+A_{0}x_{0}^{k