# How to draw a curved line in tikz-cd instead of tikz?

I was working on a project and was trying to give Tikz-cd a shot but I was having trouble with adding a curved arrow beneath from one end to the other.

I have done something similar to this between two nodes before just using tikz, but since nodes aren't necessarily defined the same way when using tikz-cd I wasn't sure how I should go back and add the line. I included the regular tikz example to show how I had done it before and my new diagram exactly as it should appear except for another curved line from 0 to 0. Can anyone help explain how to do this in the new setting? Also, the new arrow does not need to be a \mapsto arrow, but ideally would be.

mwe:

\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath,amssymb}
\usepackage{graphicx,tikz,tikz-cd}
\usepackage[margin=2.25cm]{geometry}
\usepackage{fancyhdr}
\pagestyle{fancy}
\cfoot{}
\begin{document}
I have done this using just Tikz in the past.
$\begin{tikzpicture}[node distance=2cm] \node (Q1){0}; \node[right of=Q1] (Q2){L}; \node[right of=Q2] (Q3){M}; \node[right of=Q3] (Q4){N}; \node[right of=Q4] (Q5){0}; \draw[->,thick] (Q1) -- (Q2); \draw[->,thick] (Q2) -- node[pos=.5,above]{\psi}(Q3); \draw[->,thick] (Q3) -- node[pos=.5,above]{\varphi}(Q4); \draw[->,thick] (Q4) --(Q5); \draw [bend left,->,dashed] (Q4) to node[pos=.5,below]{\alpha}(Q3); \draw [bend left,->,dashed] (Q3) to node[pos=.5,below left]{\beta}(Q2); \end{tikzpicture}$

Now I am trying to switch to using Tikz-cd, and I would like to add a curved under arrow from the zero on one end to the other. I have been able to solve the rest of it but I am not very fluent with the tikz-cd syntax yet.

$\begin{tikzcd}[node distance=2cm] 0 \arrow[mapsto]{r}{\varphi^{(1)}_{1}} & 24 \arrow[mapsto]{r}{\varphi^{(1)}_{1}} & 17 \arrow[mapsto]{r}{\varphi^{(1)}_{1}} & 18 \arrow[mapsto]{r}{\varphi^{(1)}_{1}} & 0 \end{tikzcd}$


\end{document}

Okay, I was able to add this line:

& 0 \arrow[mapsto, bend left]{l}


which got me the curved line, but only back one node instead of 4 if that helps.

tikz-cd basically a matrix of nodes or, in other words, a table. So if you write \arrow[mapsto, bend left]{l} it goes left (l) only one node, because you're indicating only one cell.

Replace it with \arrow[mapsto, bend left]{llll}.

• Excellent, that makes sense. I remember reading something in the docs about it having some kind of node matrix but that aspect hadn’t' leapt out at me. – Tristen Mar 25 '16 at 19:56

This can be another approach with tikz-cd.

\documentclass[a4paper,12pt]{article}

\usepackage{tikz-cd,amsmath,amssymb}

\begin{document}
\begin{tikzcd}
0 \arrow[r, "\varphi^{(1)}_{1}", maps to] & 24 \arrow[r, "\varphi^{(1)}_{1}", maps to] & 17 \arrow[r, "\varphi^{(1)}_{1}", maps to] & 18 \arrow[r, "\varphi^{(1)}_{1}", maps to] & 0 \arrow[llll, maps to, bend left]
\end{tikzcd}
\end{document}