2

I have this MWE:

\documentclass{amsart}
\usepackage[cmtip, all]{xy}
\begin{document}
\xymatrix@R=2pc@C=2pc{ f\in\mathcal C^1(D)   \ar@<.8ex>@{=>}[r] \ar@<-.8ex>@{<=}[r]|{\SelectTips{cm}{}\object@{/}}|{}  & f\,\text{differenziabile} \ar@<.8ex>@{=>}[r] \ar@<-.8ex>@{<=}[r]|{\SelectTips{cm}{}\object@{/}}|{} & f \,\substack{\text{derivabile} \\ \text{parzialmente}}\\
            &  f\,\text{continua} & }
\end{document}

but at this moment I am not able to put the backticks in the center of the arrows and to put implies and not implies like in the picture below:

enter image description here

Any suggestions? No tikz-cd please.

3
  • 1
    May I ask why tikz-cd is off the table?
    – Skillmon
    Apr 20 at 19:42
  • @Skillmon Why I must sent a code to a Prof. that not know tikz-cd.
    – Sebastiano
    Apr 20 at 19:46
  • 1
    In that case I'd still not rule out tikz-cd. Sometimes professors are willing to learn new things if they're worth it... (note: I don't have any opinion about tikz-cd, I never used it myself, but maybe it gets used because it does things good?).
    – Skillmon
    Apr 20 at 21:13

1 Answer 1

6

I'd not use xy.

\documentclass{article}
\usepackage{amsmath}
\usepackage{centernot,array,graphicx}

\begin{document}

\[
\newcommand{\Doublearrows}[2]{% #1 = above, #2 = below
  \mathrel{\raisebox{-0.8ex}{\vbox{\offinterlineskip\ialign{##\cr$#1$\cr$#2$\cr}}}}%
}
\newcommand{\Downlongarrow}{%
  \rotatebox[origin=c]{-90}{$\Longrightarrow$}%
}
\newcommand{\Upnotlongarrow}{%
  \rotatebox[origin=c]{90}{$\centernot{\Longrightarrow}$}%
}
\setlength{\arraycolsep}{0pt}
\begin{array}{c >{{}}c<{{}} c >{{}}c<{{}} c}
f\in\mathcal{C}^1(D) &
\Doublearrows{\mspace{1mu}\Longrightarrow}{\centernot{\Longleftarrow}\mspace{1mu}} &
f\mbox{ differenziabile} &
\Doublearrows{\mspace{1mu}\Longrightarrow}{\centernot{\Longleftarrow}\mspace{1mu}} &
f\ \smash[b]{\substack{\text{derivabile} \\ \text{parzialmente}}} \\
&& \Downlongarrow\;\Upnotlongarrow \\
&& f\mbox{ continua}
\end{array}
\]

\end{document}

enter image description here

I doubt a lot about the usefulness of such diagrams, from a pedagogical point of view.

3
  • +1 In meanwhile thank you very much for your precious time. Why is there a pedagogical problem? Please can you put also a version with xy package? The explanation is more long of the reason to use xy.
    – Sebastiano
    Apr 20 at 20:25
  • 1
    @Sebastiano Mainly because “does not imply” is too informal and might induce wrong ideas.
    – egreg
    Apr 20 at 20:36
  • I have understood. I have seen the graph from a note on the net.
    – Sebastiano
    Apr 20 at 20:38

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