%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-3-11 on page II-160 in "amscd --- Commutative diagrams a là AMS".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{183.0pt}

%StartShownPreambleCommands
\usepackage{amsmath,amscd}
\DeclareMathOperator\add{add}
\DeclareMathOperator\cf {cf}
\DeclareMathOperator\cov{cov}
\DeclareMathOperator\non{non}
%StopShownPreambleCommands

\begin{document}
\[ \begin{CD}
     \cov (L) @>>> \non (K) @>>> \cf (K)  \\
       @VVV          @AAA          @AAA   \\
     \add (L) @>>> \add (K) @>>> \cov (K) \\
   \end{CD} \]
\end{document}
