# Bifurcating a PDF: choosing a “Plan B” during a talk

I think this is a greenhorn's question, but anyway. It is sometimes difficult to measure time for a talk, according to unknown places and audiences.By this and other reasons I'd like to subtly launch a hidden "Plan B" (or, why not, a longer plan C) during my talk. Specifically

Question: Is it possible to generate a PDF that allows one to take decisions when giving a talk. That is, if at some point of the talk, one notices that one ran out of time, to manually choose a shorter sequence of slides?

(The optimal solution may be having enough practice giving talks - not my case)

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You can add the "Plan B" after your last slide, and then you'd simply press <END> and go backwards ;) –  tohecz Nov 3 '12 at 16:57
@tohecz Clever solution indeed but how to adjust where it starts from? –  percusse Nov 3 '12 at 16:58
If you know where it could be possible to switch to plan b add a link (perhaps in a second pdf, if not possible in the same pdf). If you do not know where you have to switch you can use a place shown on all sides to switch, for example a logo or your displayed name etc. I use this in nearly all presentations I have to hold. –  Kurt Nov 3 '12 at 17:49
I like presentations with links labelled "Skip Proof" particularly when the person clicks on them. I have a suspicion that some speakers put those links in even when there is no proof to skip just to give the impression that they're skipping bits. –  Andrew Stacey Nov 3 '12 at 22:17
I really like the question. I normally put slides where I am unsure that I can cover them into an Appendix and create a simple link to them from the relevant slide (i.e. Proof [link]; on the Proof page, link back to the original page). I am not sure that I as a presenter would be capable of managing different scenarios during the actual talk, i.e. I would probably confuse myself if the order of the main slides is different to what I am used to. –  Jörg Nov 4 '12 at 9:44

Merging some of the suggestions, an answer boils down to the code bellow. Here, one has introduced a pair of links (with\hyperlink) in a strategic slide. By getting there, one sees the remaining time and decides one of three options: go ahead with the normal presentation; take a shorter Plan B, which can be further reduced by skipping proofs; or take a longer path, Plan C by clicking the frame title.

\documentclass[english]{beamer}
\usepackage{babel}
\usetheme{Berlin}
\begin{document}

\begin{frame}
% if there is enough time
\begin{itemize}
\item
Is your time, say, less 20 minutes?  $\Rightarrow$ click the TeX.SE logo:
\item Have you abount 30 minutes $\Rightarrow$ click nothing and go ahead.
\item You have much more than 30 min. $\Rightarrow$ click the frame title
\end{itemize}
\begin{flushright}
\vspace{-4cm}
% shorter plan B''
\includegraphics[width=4cm]{tex.jpg}}
\end{flushright}
\end{frame}

\begin{frame}
\frametitle{Part of the usual course of the Talk}
\begin{flushright}
\vspace{-2cm}
\includegraphics[width=4cm]{tex.jpg}
\end{flushright}
Any thing here...
\end{frame}

\begin{frame}[label=planB]
\frametitle{Plan B}
\begin{flushright}
\vspace{-.2cm}
\includegraphics[width=4cm]{tex.jpg}
\end{flushright}
Set of Slides sumarizing what would have being a
talk without hurries.\\

To sumarize even more, the proof
of the following theorem can be skipped.
$a^2+b^2=c^2$
\end{beamerboxesrounded}
% just after the proof.
\end{frame}

\begin{frame}[label=planB]
% one arrives to this slide
% slide by clicking the TeX.SE
% logo in the first slide.
\frametitle{Proof of the Theorem}
\begin{flushright}
\vspace{-2cm}
\includegraphics[width=4cm]{tex.jpg}
\end{flushright}
This slide was skipped by clicking
Skip proof'' in the previous one.
\end{frame}

\begin{frame}[label=nexttoproof]
\frametitle{After the proof}
\begin{flushright}
\vspace{-2cm}
\includegraphics[width=4cm]{tex.jpg}
\end{flushright}
Set of Slides sumarizing what would have being a
talk without hurries.
\end{frame}

\begin{frame}[label=planC]
% one arrives to this
% slide by clicking the frame
% in the first slide.
\frametitle{Plan C}
\begin{flushright}
\vspace{-2cm}
\includegraphics[width=4cm]{tex.jpg}
\end{flushright}
Set of Slides boardening the talk (nobody had questions, time for more slides).
\end{frame}

\end{document}


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of course, in real life, the logo should be something more sublte :) not that big. –  c.p. Nov 3 '12 at 23:00
Could you add some general explanations to your answer, which mechanisms and commands you use? It's quite unhandy to scroll back and forth between the code and the output which are both rather long and to guess what happens where. –  Benedikt Bauer Nov 5 '12 at 6:55
Aber gern, @BenediktBauer! :) I added some description. Also, the displayed text is now self-explanatory. –  c.p. Nov 5 '12 at 15:04
Thanks a lot! Now it gets clearer. –  Benedikt Bauer Nov 5 '12 at 15:15