I would like the double arrow in the center to be bend. Here is what I have now:
\[\begin{tikzcd}
\bullet \arrow[bend left=75]{rr}[name=O]{ff'} \arrow[bend right=75]{rr}[name=S,swap]{gg'}
\arrow[bend left=50]{r}[name=U]{f}
\arrow[bend right=50]{r}[name=D,below]{g}
& \bullet
\arrow[Rightarrow,to path=(U) -- (D)]{}
\arrow[bend left=50]{r}[name=W]{f'}
\arrow[bend right=50]{r}[name=E,below]{g'}
& \bullet
\arrow[Rightarrow,to path=(W) -- (E)]{}
\arrow[Rightarrow,to path=(O) -- (S)]{}
\end{tikzcd}\]
All my attempts have failed.
\documentclass{...}
, the required\usepackage
's,\begin{document}
, and\end{document}
. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to give you a hand. Help them help you: remove that one hurdle between you and a solution to your problem. – dexteritas Sep 13 '17 at 16:22