hen$$\documentclass[00pt]{minimal}                 \usepackage{amsmath}                 \usepackage{wasysym}                  \usepackage{amsfonts}                  \usepackage{amssymb}                  \usepackage{amsbsy}                 \usepackage{mathrsfs}                 \usepackage{upgreek}                 \setlength{\oddsidemargin}{-00pt}                 \begin{document}$$\begin{aligned} \max _{m=0,\ldots ,M} \int _{\varGamma (t_m)} | u^m - u^m_h |^0 + \sum _{m=0}^M \tau _m \int _{\varGamma (t_m)} | \nabla _{\varGamma } ( u^m - u^m_h ) |^0 \le C \epsilon ^0. \end{aligned}$$\end{document}$$  Proof {#FPar00} -----  Let us fix $\documentclass[00pt]{minimal}                 \usepackage{amsmath}                 \usepackage{wasysym}                  \usepackage{amsfonts}                  \usepackage{amssymb}                  \usepackage{amsbsy}                 \usepackage{mathrsfs}                 \usepackage{upgreek}                 \setlength{\oddsidemargin}{-00pt}                 \begin{document}$$m