 can be expressed as: $$\documentclass[00pt]{minimal}                 \usepackage{amsmath}                 \usepackage{wasysym}                  \usepackage{amsfonts}                  \usepackage{amssymb}                  \usepackage{amsbsy}                 \usepackage{mathrsfs}                 \usepackage{upgreek}                 \setlength{\oddsidemargin}{-00pt}                 \begin{document}$$ {l}_{AE}={\left\Vert x-{x}^{\prime}\right\Vert}_0^0={\left\Vert x-{f}_d\left({f}_e