4

I just could draw the one with four arrows up parallel with one longer down also with appropriate spacing:

enter image description here.

Upc
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  • 1
    I voted to keep this question open because, while this different question (and its answers) contains exaclty the same drawing, the question itself is distinct. If anyone wants to add another possibility to draw this in the future, I would say that the new answer should go here, not there. (Though the usefulness of a "How to draw this" question in general is, of course, dubious.) – schtandard Jun 06 '19 at 10:57
  • I voted to reopen the question because it does not fit the duplicate and because it has good answers. However I think you should ask a new question instead of editing this one... – Phelype Oleinik Jun 07 '19 at 13:12
  • I reopened the question because the post that this was suggested to be a duplicate of really was on something completely different. –  Jun 07 '19 at 16:24

3 Answers3

7

Not trivial…

The \times\mathbb{P}^1 part is set in a zero width box.

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

\begin{document}

\begin{tikzcd}[row sep=3em,column sep=3em]
& M_{0,4}\mathrlap{{}\times\mathbb{P}^1}
  \arrow[d,"\pi"',"\;\bigg\uparrow\bigg\uparrow\bigg\uparrow\bigg\uparrow\sigma_i"]
\\
B \arrow[r,"\kappa"'] & M_{0,4}
\end{tikzcd}

\end{document}

There are possibly different ways.

enter image description here

egreg
  • 1,121,712
  • @Sigur: This works totally well. But I wanted the pullback diagram. The "bug" refers to the arrow problem. I edited here, but someone suggested me to post a new question. So I deleted it. I think you saw my new post too. – Upc Jun 07 '19 at 13:58
6

With this answer it is very easy. You can use the nodes for anything you want.

\documentclass{article}
\usepackage{tikz-cd}
\usepackage{amsmath,amssymb}
\begin{document}
\begin{tikzcd}[column sep=2.5em,row sep=2.5em,execute at end picture={
\foreach \X in {1,2,3,4}
{\draw[latex-,shorten >=1pt,shorten <=1pt] ([xshift=\X*1ex-1ex]M1.south east)  coordinate
(aux-\X) -- 
(aux-\X|-M2.north)
\ifnum\X=4
node[midway,right] {$\sigma_i$}
\fi;}
}]
  &  |[alias=M1,text width=width("$M_{0,4}$")]|M_{0,4}\times \mathbb{P}^1
  \arrow[d,"\pi" swap]  \\
 B \arrow[r,"\kappa" swap] & |[alias=M2]| M_{0,4} \\
\end{tikzcd}

\begin{tikzcd}[column sep=2.5em,row sep=2.5em,execute at end picture={
\foreach \X in {1,2,3,4}
{\draw[latex-,shorten >=1pt,shorten <=1pt] ([xshift=\X*1ex-1ex]M1.south east)  coordinate
(aux-\X) to[out=-90,in=80-\X*10] (M2)
\ifnum\X=4
node[midway,right] {$\sigma_i$}
\fi;}
}]
  &  |[alias=M1,text width=width("$M_{0,4}$")]|M_{0,4}\times \mathbb{P}^1\arrow[d,"\pi" swap]  \\
 B \arrow[r,"\kappa" swap] & |[alias=M2]| M_{0,4} \\
\end{tikzcd}

\begin{tikzcd}[column sep=4.5em,row sep=2.5em,execute at end picture={
\foreach \Y in {1,2} {\foreach \X in {1,2,3,4}
{\draw[latex-,shorten >=1pt,shorten <=1pt] ([xshift=\X*1ex-1ex]M1\Y.south east)  coordinate
(aux-\X) -- (aux-\X|-M2\Y.north)
\ifnum\X=4
node[midway,right] {$\sigma_i\ifnum\Y=1 '\fi$}
\fi;}}
}]
 |[alias=M11,text width=width("$B'$")]|B'\times \mathbb{P}^1  
 \arrow[r,shorten <=2.1em] \arrow[d,"\pi'" swap]
 &  |[alias=M12,text width=width("$B$")]|B\times \mathbb{P}^1\arrow[d,"\pi" swap]  \\
 |[alias=M21]| B' \arrow[r,"\phi" swap]  & |[alias=M22]| B \\
\end{tikzcd}
\end{document}

enter image description here

As you can see more clearly in the second example, the advantage of this hybrid approach is that you have access to the full TikZ machinery while keeping the tikz-cd functionality.

  • If you use \foreach \X in {1,2,3,4} {\draw[latex-,shorten >=1pt,shorten <=1pt,line width=0.3pt] ([xshift=\X*1ex-1ex]\tikzcdmatrixname-1-2.south east) -- ([xshift=\X*1ex-1ex]\tikzcdmatrixname-1-2.south east|-\tikzcdmatrixname-2-2.north) \ifnum\X=4 node[midway,right] {$\sigma_i$} \fi;} the arrows resemble those on your screen shot even more. –  Jun 04 '19 at 20:42
  • @marmor: This is nice too. Can this be modified to my need as I discribed again? – Upc Jun 07 '19 at 12:19
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    @Upc I added this here. With shorten you can also fix your code that is based on egreg's answer but IMHO on the long run you may want to switch to the execute at end picture because you can access all features of TikZ, or use TikZ only, as in Black Mild's nice answer. –  Jun 07 '19 at 14:18
3

TikZ is enough for (most) block figures. 

\documentclass[tikz,border=5mm]{standalone}
\usepackage{amsmath,amssymb}
\begin{document}
\begin{tikzpicture}[>=latex]
\path 
(0,0) node (M) {$M_{0,4}$}
+(180:2) node (B) {$B$}
++(90:1.5)+(0:.3) node (P) 
{$M_{0,4}\times \mathbb{P}^1$};

\draw[->] (B)--(M) node[below,midway]{$\kappa$}; 
\draw[<-,shorten >=2mm] (M.120)--(P-|M.120) 
node[left,midway]{$\pi$};
\foreach \i in {0,1,2}
\draw[->] (M.45)++(90:1mm)++(0:\i*1.5mm)--+(90:.8);
\draw[->] (M.45)++(90:1mm)++(0:3*1.5mm)--+(90:.8)
node[right,midway]{$\sigma_i$};
\end{tikzpicture}
\end{document}

enter image description here

Black Mild
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