Commutative diagrams side by side have different sizes

Question

Within the statement of a theorem, I have two commutative diagrams. I am trying to use pb-diagram to create them and I would like them to be side by side. Unfortunately the size of the commutative diagrams seem to depend on the size of the symbols at the nodes, and the two commutative diagrams come out to be different sizes. Is there any way to fix this?

Here is the code I have right now:

\documentclass[12pt]{amsart}
\usepackage[arrow,matrix,curve,cmtip,ps]{xy}
\usepackage{pb-diagram} 
\usepackage{pb-xy}
\usepackage{amsmath,amsthm,amssymb}
\begin{document}
\begin{equation}
\begin{diagram}
\node{\mathcal{C}_R}\arrow{e,t}{P}\arrow{s,l,J}{\Psi}\node {\mathcal{C}_R}\arrow{s,l,J}{\Psi}\\
\node{\widehat{\mathcal{C}}_R}\arrow{e,t}{E(P)}\node{\widehat{\mathcal{C}}_R}
\end{diagram}\hspace{40pt}
\begin{diagram}
\node{\mathcal{C}_{R,\,\operatorname{top}}}\arrow{e,t}{P}\arrow{s,l,J}{\Psi}\node {\mathcal{C}_{R,\,\operatorname{top}}}\arrow{s,l,J}{\Psi}\\
\node{\widehat{\mathcal{C}}_{R,\,\operatorname{top}}}\arrow{e,t}{E(P)}\node{\widehat{\mathcal{C}}_{R,\,\operatorname{top}}}
\end{diagram}
\end{equation}
\end{document}

and here is the result of compiling:

enter image description here

Welcome to TeX.sx! Feel free to visit our TeX.SX starter guide to get the most out of the site — Peter Jansson, May 20 '13 at 17:10
Could you provide the contents of a complete compilable .tex file, starting with \documentclass? In particular, I'm wondering which package you're loading to get the diagram environment. — John Wickerson, May 20 '13 at 17:17
@JohnWickerson I just added those details, I really should have done so at the outset, sorry! — Aru Ray, May 20 '13 at 17:44

score 10 · Accepted Answer · edited Jun 09 '17 at 19:28

I don't know how to do with pb-diagram, which is a very old package. A more modern one, and more powerful too, is tikz-cd:

\documentclass{article}
\usepackage{tikz-cd}
\usepackage{pb-diagram}
\newcommand{\C}{\mathcal{C}}
\newcommand{\Chat}{\hat{\C}}
\renewcommand{\top}{\mathrm{top}}
\begin{document}
\begin{equation}
\begin{tikzcd}
\C_R \arrow{r}{P} \arrow[hookrightarrow,swap]{d}{\Psi} &
\C_R \arrow[hookrightarrow,swap]{d}{\Psi}\\
\Chat_R \arrow{r}{E(P)} & \Chat_R
\end{tikzcd}\hspace{40pt}%
\begin{tikzcd}
\C_{R\smash{,\,\top}} \arrow{r}{P} \arrow[hookrightarrow,swap]{d}{\Psi} &
\C_{R\smash{,\,\top}} \arrow[hookrightarrow,swap]{d}{\Psi}\\
\Chat_{R\smash{,\,\top}} \arrow{r}{E(P)} & \Chat_{R\smash{,\,\top}}
\end{tikzcd}
\end{equation}
\end{document}

It's necessary to "smash" the comma and the word "top", because they have descenders that would make the second diagram a bit larger.

enter image description here

score 3 · Answer 2 · answered May 20 '13 at 20:57

As you are using xy-pic, it can alone draw commutative diagrams.

Code:

\documentclass[12pt]{amsart}
\usepackage[all]{xy}
\begin{document}
\[
\xymatrix{
& \mathcal{C}_R \ar@{^{(}->}[d]_{\Psi} \ar[r]^P & \mathcal{C}_R \ar@{^{(}->}[d]_{\Psi}\\ 
& \widehat{\mathcal{C}}_R \ar[r]^{E(P)} & \widehat{\mathcal{C}}_R }

\xymatrix{
& \mathcal{C}_{R,\,\mathrm{top}} \ar@{^{(}->}[d]_{\Psi} \ar[r]^P 
& \mathcal{C}_{R,\,\mathrm{top}} \ar@{^{(}->}[d]_{\Psi} \\ 
& \widehat{\mathcal{C}}_{R,\,\mathrm{top}} \ar[r]^{E(P)} 
& \widehat{\mathcal{C}}_{R,\,\mathrm{top}} }
\end{document}

Output:

Commutative diagrams side by side have different sizes

2 Answers2