%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 5-2-2 on page 78.
%% 
%%  Copyright (C) 2009 Herbert Voss
%% 
%%  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{355.65944pt}
\setlength\parindent{0pt}
\setcounter{equation}{0}
\renewcommand\theequation{5.\arabic{equation}}
\StartShownPreambleCommands
\usepackage{xcolor,amsmath,amscd}
\StopShownPreambleCommands
\begin{document}
\[ \color{magenta}\left(\prod^n_{\, j=1}\hat{x}_j\right)H_c=%
     \frac{1}{2}\hat{k}_{ij}\det\widehat{\mathbf{K}}(i|i) \]

\begin{align}\color{blue}
\begin{CD}
  R\times S\times T @>\text{restriction}>> S\times T \\
        @VprojVV                            @VVprojV \\
  R\times S         @<<\text{\textcolor{red}{inclusion}}<   S
\end{CD}
\end{align}
\end{document}