%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 8-6-3 on page 501.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

\StartShownPreambleCommands
\usepackage[fleqn]{amsmath}
\DeclareMathOperator \meas    {meas}
\DeclareMathOperator*\esssup  {ess \, sup}
\DeclareMathOperator*\supminus{sup - minus*}
\newcommand\abs [1]{\lvert#1\rvert}
\newcommand\norm[1]{\lVert#1\rVert}
\StopShownPreambleCommands
\begin{document}
\begin{gather*}
  \norm{f}_\infty = \esssup_{x \in R^n} \abs{f(x)}  \\
  \meas_1 \{ u \in R_+^1 \colon f^*(u)>\alpha \} =  \\
  \quad \esssup_{x \in R^i} \; \meas_i
     \{ u \in R^n \colon \abs{f(u)} \geq \alpha \}  \\
  \quad (\forall \alpha \in \supminus_{f^*} R_{*+})
\end{gather*}
\end{document}
