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I'd like to improve the following diagram for a pair of adjoint functors: enter image description here

This is the code:

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

\begin{document}
    \[
        \begin{tikzcd}
            \mathcal{D}\arrow[r, shift left=.75ex, "G"{name=G}] & \mathcal{C}\arrow[l, shift left=.75ex, "F"{name=F}] 
            \arrow[phantom, from=F, to=G, "\dashv" rotate=90].      
        \end{tikzcd}
    \]
\end{document}

Is there a standard diagram for a pair of adjoint functors?

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  • 1
    It is also not entirely clear (at least to me) what you're asking. The diagram looks fine as far as I can tell, so is it the code usde to create it that you would like to improve? Feb 10, 2019 at 14:09
  • Thank you for your suggestions, I've just done it. I'd like to improve how the diagram looks, e.g. maybe making the \dashv symbol a bit smaller (?).
    – Vladimir
    Feb 10, 2019 at 14:18
  • To make it smaller you could replace \dashv by either \scriptstyle\dashv or \scriptscriptstyle\dashv. Feb 10, 2019 at 14:22
  • It is really hard to answer this question because it is not clear what "improve" means. Some might bend the arrows, some may make the symbol smaller, some may add colors and others may add ducks. Could you perhaps add a sketch of the desired outcome?
    – user121799
    Feb 10, 2019 at 17:34

1 Answer 1

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How about this? I use \top in the place of a rotated \dashv·

\documentclass{article}
\usepackage{amsmath,amssymb,tikz-cd}
\newcommand{\C}{\mathcal{C}}
\newcommand{\D}{\mathcal{D}}

\begin{document}

    \[
        \begin{tikzcd}
            \D\arrow[r, shift left=1ex, "G"{name=G}] & \C\arrow[l, shift left=.5ex, "F"{name=F}]
            \arrow[phantom, from=F, to=G, , "\scriptscriptstyle\boldsymbol{\top}"].
        \end{tikzcd}
    \]
\end{document}

enter image description here

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  • Peraphs (but from the initial picture it is not very clear) the \top is written in bold. However you have always my appreciations.
    – Sebastiano
    Feb 10, 2019 at 16:15
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    @Sebastiano: maybe it depends on the font. Anyway, I tested with \boldsymbol and indeed, it looks better from my point of view, so I added it to my code Thanks for drawing my attention on this point!
    – Bernard
    Feb 10, 2019 at 16:23
  • Yes of course! :-) You colud add also another code with \intercal (instead of \top) if you want :-).
    – Sebastiano
    Feb 10, 2019 at 16:27
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    @Sebastiano: I didn't think of that (I very seldom use this symbol), but having tested, I find it too heavy, even without \boldsymbol.
    – Bernard
    Feb 10, 2019 at 16:38
  • Don't worry about it at all. I always respect the tastes of others. \intercal I has been used simply without bold in my book :-)
    – Sebastiano
    Feb 10, 2019 at 16:41

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