1

How do I type this commutative diagram in tikz-cd in overleaf?

enter image description here

I have tried this

\documentclass{amsart}
\usepackage{latexsym,amsmath}
\usepackage{mathtools}
\usepackage{scalerel,stackengine}
\usepackage{tikz-cd}
\begin{document}

\maketitle
\[
\begin{tikzcd}
G \arrow[r,""]\arrow[d,swap,"\Delta"]\arrow[rd,swap,"\id_G"] & 1 \times G \arrow[r,"e \times id_G"]  &
  G \times G \arrow[d,"m"] \\
G \times 1 \arrow[d,"id_G \times e"] \\
G \times G \arrow[r,"m"] & G
\end{tikzcd}
\]
\end{document}

which is not working.

4
  • Welcome to TSE. Please post a Minimal Working Example, instead of a code snippet. Commented Dec 7, 2021 at 8:53
  • @JoséCarlosSantos What is minimal working? I am really sorry as I am new here.
    – Ri-Li
    Commented Dec 7, 2021 at 9:00
  • 1
    Take a look here. Commented Dec 7, 2021 at 9:02
  • @JoséCarlosSantos got it. I have edited it.
    – Ri-Li
    Commented Dec 7, 2021 at 18:21

1 Answer 1

3

The trick is to consider this as a 3-by-3 matrix. So the diagonal arrow should be rrdd, because it has to jump over two columns and two rows.

Similarly, in the last row you need &&, because the center column has no entry.

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

\newcommand{\id}{\mathrm{id}}
\newcommand{\one}{\mathbf{1}}

\begin{document}

\[
\begin{tikzcd}[column sep=3em]
%% first row
G \arrow[r] \arrow[d,swap,"\Delta"] \arrow[rrdd,"\id_G"] &
\one \times G \arrow[r,"e \times \id_G"]  &
G \times G \arrow[dd,"m"] \\
%% second row
G \times \one \arrow[d,swap,"\id_G \times e"] \\
%% third row
G \times G \arrow[rr,"m"] && G
\end{tikzcd}
\]

\end{document}

I increased a tad the column separation, so as to avoid the label in the top row overfilling the arrow.

I'm not sure I'd label that arrow by “Delta” that suggests “diagonal”, but you've the final word on this.

enter image description here

3
  • I have a general question what does the 'swap' mean when we are drawing the down arrow?
    – Ri-Li
    Commented Dec 7, 2021 at 18:26
  • I got it the map will be on the other side of the arrow. Many many thanks :) 😊
    – Ri-Li
    Commented Dec 7, 2021 at 18:30
  • @Ri-Li You can also type "<label>"' (with an apostrophe after the closing double quote). By default, labels are printed on the left side: imagine to be standing on the source of the arrow and to look towards the target.
    – egreg
    Commented Dec 7, 2021 at 18:47

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