# How do I add two sided arrow in this chain of commutative diagram?

I want to build a chain of commutative diagram

I did get the code here for building the commutative diagram. This is the code.

\documentclass[12pt,twoside,a4paper]{report}
\usepackage{tikz-cd}
%\newcommand{\nospaceperiod}{\makebox[0pt][l]{\,}}
\begin{document}
$\begin{tikzcd} V_1 \arrow{r} \arrow{d}{f_1} & V_2 \arrow{r} \arrow{d}{f_2} & \cdots \arrow{r} & V_{n-1} \arrow{r} \arrow{d}{f_{n-1}} & V_n \arrow{d}{f_n} \\ W_1 \arrow{r} & W_2 \arrow{r} & \cdots \arrow{r} & W_{n-1} \arrow{r} & W_n \end{tikzcd}$
\end{document}


which gives this output

I am almost done. I just want to know what do I change in \arrow{r} to make the right arrow to be two sided arrow or hook arrow or curved arrow.

I want output to look like these

Please share some manual that gives different keywords for different kind of arrows.

• Simply use an option to arrow: \arrow[<->]{r}. May 3 '19 at 15:07
• To bend the arrow: \arrow[bend right]{r} or \arrow[bend left]{r}. May 3 '19 at 15:09
• Thank you.. \arrow[<->]{r} works. But how do add a curved arrow from one variable to other surpassing one or more middle variables.. Like in the last diagram above ? May 3 '19 at 15:13
• Use r twice: \arrow[bend right]{rr} May 3 '19 at 15:14
• That works well :) Thank you May 3 '19 at 15:17

## 1 Answer

For two sided arrow, simply replace it by: \arrow[<->]{r}.

To bend the arrow, use: \arrow[bend right]{r} or \arrow[bend left]{r}

Use \arrow[bend right]{rr}to point the curved arrow to next but one variable.

To get the output as in last image, use this code

\documentclass{report}
\usepackage{tikz-cd,bbm,amsmath,amssymb}

\begin{document}
$\begin{tikzcd} I \arrow{r}{s} \arrow[bend right]{rr}{\mathbbm{1}} & X^c \arrow{r}{p} & I \end{tikzcd}$
\end{document}