0

I am just trying to put some labels on the right side of some commutative diagrams in order to later reference them. Since I am not labeling all diagrams, as I only need to reference two of them, I would prefer symbols rather than numbers. Anyway, the closest I can get is by typing

\begin{equation}  \label{tre}
    
\begin{center}   


    \begin{tikzcd}
    
    S^n(X'') \arrow{d}{S^n(h'')} \arrow{r}{\delta^n_E}     &         S^{n+1}(X')   \arrow{d}{S^{n+1}(h')}     \\
    S^n(Y'')     \arrow{r}{\delta^n_F}  &        S^{n+1}(Y')
    
    
    \end{tikzcd}  
    
\end{center}  \tag{\bullet}


\end{equation}

Now, besides the fact that I get several warnings such as "Package amsmath Error: \tag not allowed here", this only displays the tag "(1.1)" in this left lower corner of my diagram (while I would prefer any label to be on the right and not on a lower line). Even weirder, if I remove the "center" environment, then Overleaf doesn't compile.

I am really confused. Can someone please help me?

2
  • Please add a MWE that we can copy and paste: documentclass and used packages as well as \begin{document} and \end{document}.
    – Unknown
    May 26 at 23:08
  • 2
    Why are you using center inside an equation in the first place? Plus blank lines are not allowed in math mode.
    – daleif
    May 26 at 23:17

2 Answers 2

5

This is not a problem of commutative diagrams or anything related to tikz. This is just a labeling issue that can be solved with amsmath or mathtools. The later provides a command to keep the tag as in the equation. Here is an example:

\documentclass{article}
\usepackage{mathtools}
\usepackage{tikz-cd}
\begin{document}
\begin{equation*}
xyz \label{blah}\tag*{$\bullet$}
\end{equation*}
The equation~\refeq{blah} is easy
\begin{equation*}
\begin{tikzcd}
A\ar{r}{f}\ar{d}[swap]{g} & B\ar{d}{h}\\
C\ar{r}[swap]{k} & D
\end{tikzcd}
\label{foo}\tag*{\&}
\end{equation*}
\textit{The diagram~\ref{foo} is commutative} vs. \textit{The diagram~\refeq{foo} is commutative} 
\end{document}

which results in: enter image description here

2

First off: blank lines are not allowed inside equation and center is also disallowed. The argument to \tag is typeset as text, so \bullet will lead to an error.

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz-cd}

\begin{document}

\begin{equation} \label{tre}
  \begin{tikzcd}
    S^n(X'') \arrow[d,"S^n(h'')"] \arrow[r,"\delta^n_E"] &
    S^{n+1}(X') \arrow[d,"S^{n+1}(h')"] \\
    S^n(Y'') \arrow[r,"\delta^n_F"] & S^{n+1}(Y')
  \end{tikzcd}  
\tag{\textbullet}
\end{equation}

\end{document}

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.