# Diagram for Limit

I want a diagram that looks like the one found here,

This is my attempt:

$\begin{tikzcd} [column sep = large] N \arrow[d, "u"] \arrow[ddr, "q_j"] \arrow[ddl, "q_k"] \\ \mathcal{A} \arrow[dr, "p_j"] \arrow[dl, "p_k"] \\ A_1 \arrow[r, "F(m)"] & A_2 \end{tikzcd}$


I notice the problems are with ddl and dl.

• Hi, and welcome to TeX.sx. You can format code by choosing the code and clicking on the {} icon. Also, it's preferable to put your code fragment into a complete compilable document: you'll get help faster, and shows which packages you have loaded to make that fragment run. – Alan Munn Oct 11 '15 at 0:47

You need three columns (I also added some bending for some arrows and swapping for some of the labels):

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

\begin{document}

$\begin{tikzcd}[row sep = large] & N \arrow[d, "u"] \arrow[ddr, bend left,"q_j"] \arrow[ddl, bend right,"q_k",swap] & \\ & \mathcal{A} \arrow[dr, "p_j"] \arrow[dl,swap, "p_k"] & \\ A_1 \arrow[rr,swap, "F(m)"] & & A_2 \end{tikzcd}$

\end{document}


Or

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

\begin{document}

$\begin{tikzcd}[row sep = large] & N \arrow[d, dashed, "u" description] \arrow[ddr, bend left,"q_j"] \arrow[ddl, bend right,"q_k",swap] & \\ & \mathcal{A} \arrow[dr, "p_j"] \arrow[dl,swap, "p_k"] & \\ A_1 \arrow[rr,swap, "F(m)"] & & A_2 \end{tikzcd}$

\end{document}


• Just wondering here, would this example get into trouble if the " was active? For example Danish babel use active ", if problematic, might be an idea to also note the alternative syntax. – daleif Oct 11 '15 at 7:22
• @daleif It's not a problem if you add \usetikzlibrary{babel}. – egreg Oct 11 '15 at 9:28
• I understand the yearning for symmetry, but the label in the middle of a dashed arrow is, at the least, ambiguous. Also the row sep should be increased. – egreg Oct 11 '15 at 9:31
• @egreg row sep increased. The first option then won't hurt your eyes. – Gonzalo Medina Oct 11 '15 at 12:18

Besides the other answers, you can utilize Tikz for this matter.

\documentclass[border={10pt}]{standalone}

\usepackage{tikz}
\usetikzlibrary{calc, positioning}

\begin{document}

\begin{tikzpicture}
[%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
node distance=2.5cm, thick,
]%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\node (Fx)                                                  {$F(X)$};
\node (Fy)[right=of Fx]                                     {$F(Y)$};
\node (L) [yshift=1.8cm] at (barycentric cs:Fx=0.1,Fy=0.1)  {L};
\node (N) [above=of L]                                      {$N$};

\draw[->,dashed] (N) -- (L)  node [rectangle,fill=white,midway] {$u$};
\draw[->] (L)  -- (Fx) node [left,midway]  {$\phi_{X}$};
\draw[->] (L)  -- (Fy) node [right,midway] {$\phi_{Y}$};
\draw[->] (Fx) -- (Fy) node [below,midway] {$F(f)$};
\draw[->] (N) to [bend right=30] node [left,midway] {$\psi_{X}$} (Fx) ;
\draw[->] (N) to [bend left=30] node [right,midway] {$\psi_{Y}$} (Fy) ;
\end{tikzpicture}
\end{document}


• Just for completeness, might want to explain the barycentric cs, users passing by, might not know it. – daleif Oct 11 '15 at 10:08

A pstricks solution:

\documentclass{article}
\usepackage{pst-node}
\usepackage{auto-pst-pdf}

\begin{document}

$\psset{arrows=->, arrowinset=0.15, linewidth=0.6pt, dash=3pt 2pt, nodesep=3pt, labelsep=1pt, colsep=1cm, rowsep=1.25cm, shortput=nab} \begin{psmatrix} & N\\ & L\\ F(X) & & F(Y)\\ \end{psmatrix} \ncline[linestyle=dashed]{1,2}{2,2}\ncput*{u} \ncline{2,2}{3,1}_{\phi_X} \ncline{2,2}{3,3}^{\phi_Y} \ncline{3,1}{3,3}_{F(f)} \ncarc[arcangle=-20]{1,2}{3,1}\nbput{\psi_X}\ncarc[arcangle=20]{1,2}{3,3}\naput{\psi_Y}$

\end{document}