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diff --git a/talks/uparis-ipopup-2021/outline b/talks/uparis-ipopup-2021/outline
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@@ -0,0 +1,7 @@
+The duration of the session was less than one, question included.  The
+audience was impatient biologists not practitioning daily computating tasks
+and with low if not none experience about how a computation runs.
+
+The components presented in this talk had been written as a blog entry, see:
+
+    https://simon.tournier.info/posts/2021-09-09-ipopup-seminar.html
diff --git a/talks/uparis-ipopup-2021/talk-20210909.pdf b/talks/uparis-ipopup-2021/talk-20210909.pdf
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+++ b/talks/uparis-ipopup-2021/talk.tex
@@ -0,0 +1,772 @@
+\documentclass[aspectratio=169]{beamer}
+
+\usetheme{default}
+
+\usefonttheme{structurebold}
+\usepackage{helvet}
+\usepackage{multimedia}         % movie
+\usecolortheme{seagull}         % white on black
+
+\usepackage[utf8]{inputenc}
+\PassOptionsToPackage{hyphens}{url}\usepackage{hyperref,xspace,multicol}
+\usepackage[absolute,overlay]{textpos}
+\usepackage{tikz}
+\usetikzlibrary{arrows,shapes,trees,shadows,positioning, decorations.pathreplacing}
+\usepackage{fancyvrb}           % for \Verb
+
+\usepackage{ulem}
+
+% Remember the position of every picture.
+\tikzstyle{every picture}+=[remember picture]
+
+\tikzset{onslide/.code args={<#1>#2}{%
+  \only<#1>{\pgfkeysalso{#2}} % \pgfkeysalso doesn't change the path
+}}
+
+% Colors.
+\definecolor{guixred1}{RGB}{226,0,38}  % red P
+\definecolor{guixorange1}{RGB}{243,154,38}  % guixorange P
+\definecolor{guixyellow}{RGB}{254,205,27}  % guixyellow P
+\definecolor{guixred2}{RGB}{230,68,57}  % red S
+\definecolor{guixred3}{RGB}{115,34,27}  % dark red
+\definecolor{guixorange2}{RGB}{236,117,40}  % guixorange S
+\definecolor{guixtaupe}{RGB}{134,113,127} % guixtaupe S
+\definecolor{guixgrey}{RGB}{91,94,111} % guixgrey S
+\definecolor{guixdarkgrey}{RGB}{46,47,55} % guixdarkgrey S
+\definecolor{guixblue1}{RGB}{38,109,131} % guixblue S
+\definecolor{guixblue2}{RGB}{10,50,80} % guixblue S
+\definecolor{guixgreen1}{RGB}{133,146,66} % guixgreen S
+\definecolor{guixgreen2}{RGB}{157,193,7} % guixgreen S
+
+\setbeamerfont{title}{size=\huge}
+\setbeamerfont{frametitle}{size=\huge}
+\setbeamerfont{normal text}{size=\Large}
+
+% White-on-black color theme.
+\setbeamercolor{structure}{fg=guixorange1,bg=black}
+\setbeamercolor{title}{fg=white,bg=black}
+\setbeamercolor{date}{fg=guixorange1,bg=black}
+\setbeamercolor{frametitle}{fg=white,bg=black}
+\setbeamercolor{titlelike}{fg=white,bg=black}
+\setbeamercolor{normal text}{fg=white,bg=black}
+\setbeamercolor{alerted text}{fg=guixyellow,bg=black}
+\setbeamercolor{section in toc}{fg=white,bg=black}
+\setbeamercolor{section in toc shaded}{fg=white,bg=black}
+\setbeamercolor{subsection in toc}{fg=guixorange1,bg=black}
+\setbeamercolor{subsection in toc shaded}{fg=white,bg=black}
+\setbeamercolor{subsubsection in toc}{fg=guixorange1,bg=black}
+\setbeamercolor{subsubsection in toc shaded}{fg=white,bg=black}
+\setbeamercolor{frametitle in toc}{fg=white,bg=black}
+\setbeamercolor{local structure}{fg=guixorange1,bg=black}
+
+\newcommand{\highlight}[1]{\alert{\textbf{#1}}}
+\newcommand{\orange}[1]{\textcolor{guixorange1}{\textbf{#1}}}
+\newcommand{\comment}[1]{\textcolor{guixgreen2}{#1}}
+\newcommand{\red}[1]{\textcolor{guixred2}{#1}}
+
+
+\title{Computational reproducibility \\ with GNU Guix: \\
+  \Large{application to multiparametric cytometry}}
+
+\author{Simon Tournier${}^1$ \& Nicolas Vallet${}^2$}
+\date{iPOP-UP, September 9th, 2021}
+\institute{%
+  \texttt{simon.tournier@u-paris.fr}
+  \  \
+  \texttt{nicolas.vallet@inserm.fr}}
+
+\setbeamertemplate{navigation symbols}{} % remove the navigation bar
+
+\AtBeginSection[]{
+  \begin{frame}
+    \frametitle{}
+    \tableofcontents[currentsection]
+  \end{frame}
+}
+
+
+\newcommand{\screenshot}[1]{
+  \begin{frame}[plain]
+    \begin{tikzpicture}[remember picture, overlay]
+      \node [at=(current page.center), inner sep=0pt]
+        {\includegraphics[width=\paperwidth]{#1}};
+    \end{tikzpicture}
+  \end{frame}
+}
+
+
+\begin{document}
+
+
+\begin{frame}[plain, fragile]
+  \vspace{10mm}
+  \titlepage
+
+  \vfill{}
+  ${}^1$Research Eng. Sci. Computing \ \scriptsize{(+little admin-sys)}
+
+  \normalsize
+  ${}^2$PhD student \ \scriptsize{(and MD)}
+
+  \normalsize
+  \hfill{%
+    \begin{minipage}{0.2\paperwidth}
+      \begin{tabular}{c|c}
+        \includegraphics[width=0.1\paperwidth]{images/diderot_u-paris}
+        &
+          \includegraphics[width=0.04\paperwidth]{images/diderot_u-paris_bis}
+      \end{tabular}
+    \end{minipage}
+  }
+\end{frame}
+
+
+\begin{frame}[plain]
+  \begin{center}
+    \begin{tabular}{rcl}
+      \textcolor{guixtaupe}{Science} & \textcolor{guixtaupe}{=} & \textcolor{guixtaupe}{Transparency}
+      \\
+      \textcolor{guixblue1}{Scientific result} & \textcolor{guixblue1}{=} &
+                                                                            \textcolor{guixblue1}{Experiment
+                                                                            +
+                                                                            \only<1>{{Numerical treatment}}
+                                                                            \only<2>{\emph{Numerical treatment}}}
+    \end{tabular}
+  \end{center}
+
+%  \vfill{}
+
+  \begin{center}
+    \highlight{Science at the numerical age:}
+  \end{center}
+
+  \begin{tabular}{cll}
+    \orange{1.} & Open Article & HAL, BioArxiv
+    \\
+    \orange{2.} & Open Data & Zenodo
+    \\
+    \orange{3.} & Open Source & GitHub, Software Heritage
+    \\
+    \uncover<2->{\orange{4.}} & \uncover<2->{\fbox{\comment{Computational env.}}} &  \uncover<2->{\alert{?}}
+  \end{tabular}
+
+  \begin{center}
+    {and how to \only<1>{glue}\only<2>{\emph{glue}} all that?}
+  \end{center}
+
+  \vfill{}
+
+    $\left(
+    \begin{tabular}{lcl}
+      reproductibility &=& verification\\
+      replicability &=& validation
+    \end{tabular}
+    \right)$
+
+    \vspace{-0.75cm}
+
+  \begin{flushright}
+    \href{https://scibian.org/up/201609/Software_Heritage.pdf}%
+    {\small{R. Di Cosmo@Scibian2016 \sout{(pdf)}}}\\
+    \href{https://aramis.resinfo.org/wiki/lib/exe/fetch.php?media=pleniaires:aramis_keynote_enjeux-et-defis-recherche-reproductible_konrad_hinsen.pdf}%
+    {\small{K. Hinsen@Aramis2019 (pdf)}}
+  \end{flushright}
+\end{frame}
+
+
+\begin{frame}{Redo (reproduce or replicate) a result?}
+  \begin{tabular}{clclclcl}
+           &&& \orange{audit} && \red{opaque} && \comment{depend?}
+    \\ \hline \\
+    & result &$\longleftarrow$& \orange{paper} &+& \red{data} &+& \comment{analysis}
+    \\ \\
+    & data &$\longleftarrow$& \orange{protocol} &+& \red{instruments} &+& \comment{materials} (reagent, etc.)
+    \\
+    \uncover<2->{\orange{$\rhd$}} & analysis &$\longleftarrow$& \orange{script} &+& \red{data} &+&
+                                               \only<-3>{\comment{environment}}\uncover<4->{\fbox{\comment{environment}}}
+    % \\ \\ \hline \\
+    % & environment &$\longleftarrow$& \orange{source} &+& \red{builder} (package) &+& packages
+    % \\
+    % & package &$\longleftarrow$& \orange{source} &+& \red{executable} &$\Big($+& packages$\Big)$
+  \end{tabular}
+
+  \vfill
+  \begin{center}
+    \begin{minipage}[c]{.8\linewidth}
+    \begin{itemize}
+    \item \orange{audit} is the ``easy'' part
+    \item \red{opaque} is generally the hard part
+    \item<3-> how to evacuate \comment{depend?} from the equations%
+      \uncover<4->{\dots \\ \hfill \dots at least let speak about \comment{environment}}
+    \end{itemize}
+    \end{minipage}
+  \end{center}
+\end{frame}
+
+
+\begin{frame}{Concrete scenarii about environment}
+  \begin{itemize}
+  \item Alice used \emph{numerical tools} \texttt{R@4.1.1}, \texttt{FlowCore@2.4} and \texttt{CATALYST@1.16.2}.
+  \item Carole \emph{collaborates} with Alice \dots \\
+    \hfill{but also requires \texttt{R@4.0.4}, \texttt{FlowCore@2.0} for another project.}
+  \item Charlie upgrades their system then all is broken.
+  \item Bob runs the \emph{same versions} as Alice \dots \\
+    \hfill{but does \emph{not} get the \emph{same outputs}.}
+  \item Dan tries to \emph{redo} the analysis months (years?) later \dots\\
+    \hfill{but hits the \emph{dependencies hell}\footnote{at best :-)}.}
+  \end{itemize}
+  \uncover<2->{
+  \begin{center}
+    \highlight{Solution(s)}
+  \end{center}
+
+  \vspace{-0.6cm}
+
+  \begin{tikzpicture}[decoration=brace]
+    \node[text width=0.6\paperwidth] (box)
+    {
+      \begin{enumerate}
+      \item \textbf{package manager}: \texttt{apt}, \texttt{yum}, etc.
+      \item \textbf{virtual environment}: \texttt{conda}, \texttt{modulefiles}, etc.
+      \item \textbf{container}: Docker, Singularity, etc.
+      \end{enumerate}
+    };
+    \draw [decorate] (box.north east) --node[right=10pt]{\alert{Guix}} (box.south east);
+  \end{tikzpicture}
+  }
+\end{frame}
+
+
+\begin{frame}[fragile]{Why is it complicated?}
+  \begin{semiverbatim}
+    alice@laptop\$ R -e '1+2'
+    > 1+2
+    [1] 3
+  \end{semiverbatim}
+
+  \vspace{-1cm}
+  \uncover<2->{
+  \begin{center}
+    What is the issue?
+    \orange{R is Open Source}
+    \\
+    \href{https://svn.r-project.org/R/trunk/src/main/main.c}%
+    {https://svn.r-project.org/R/trunk/src/main/\orange{main.c}}
+  \end{center}
+  }
+
+  \vspace{-0.25cm}
+  \uncover<3->{
+  \begin{semiverbatim}
+    alice@laptop\$ file \only<-8>{/usr/lib/R/bin/exec/R}\only<9->{\red{/usr/lib/R/bin/exec/R}}
+
+    /usr/lib/R/bin/exec/R: \only<3>{executable}\only<4->{\red{executable}}, dynamically \only<3-8>{linked}\only<9->{\comment{linked}}, ...
+  \end{semiverbatim}
+  }
+
+  \uncover<5-8>{
+    Recipe to make an \only<5>{yogurt}\only<6->{\sout{yogurt} executable}:
+    \begin{center}
+      \begin{tabular}{lclcl}
+        Yogurt &$\longleftarrow$& Milk &+& Skyr\only<5-8>{\footnote{Icelandic strained yogurt}}
+        \uncover<6->{
+        \\
+        \red{executable} && \orange{source} && \only<5-7>{\red{executable}}
+        } \uncover<7->{\\
+        R && \texttt{main.c} && C compiler
+        } \uncover<8->{\\
+          && && \red{executable} $\leftarrow$ \orange{source} ~+~ \red{executable}
+        }
+      \end{tabular}
+    \end{center}
+  }
+
+  \vspace{-2.25cm}
+  \begin{semiverbatim}
+  \uncover<10-11>{
+    alice@laptop\$ ldd \red{/usr/lib/R/bin/exec/R}\only<10>{
+        libblas.so.3 => /usr/lib/x86_64-linux-gnu/libblas.so.3
+        libR.so => /usr/lib/libR.so
+        libgfortran.so.5 => /usr/lib/x86_64-linux-gnu/libgfortran.so.5
+        libquadmath.so.0 => /usr/lib/x86_64-linux-gnu/libquadmath.so.0}\only<11->{
+        libblas.so.3 => \red{/usr/lib/x86_64-linux-gnu/libblas.so.3}
+        libR.so => \red{/usr/lib/libR.so}
+        libgfortran.so.5 => \red{/usr/lib/x86_64-linux-gnu/libgfortran.so.5}
+        libquadmath.so.0 => \red{/usr/lib/x86_64-linux-gnu/libquadmath.so.0}}
+        ...}
+  \end{semiverbatim}
+
+  \only<12->{
+  \vspace{-1.25cm}
+  \begin{flushright}
+    \href{https://webcast.in2p3.fr/video/les-enjeux-et-defis-de-la-recherche-reproductible}%
+    {\small{K. Hinsen@Aramis2019 (video)}}
+
+    \href{https://hpc.guix.info/blog/2020/01/reproducible-computations-with-guix/}%
+    {Blog: Reproducible computations with Guix (link)}
+  \end{flushright}
+  }
+\end{frame}
+
+
+\begin{frame}{Is it really so complicated?}
+  \begin{itemize}
+  \item Wait!  \highlight{Package managers}
+    (\texttt{apt}, \texttt{yum}, \texttt{conda}, \texttt{brew}, etc.)
+    do the \emph{job for us}.
+  \item Yes, but\dots \ \uncover<7->{e.g., \highlight{Conda is not enough}}
+    \begin{center}
+      \begin{tabular}{cclclcl}
+        \uncover<2->{
+        Yogurt &$\longleftarrow$& Milk &+& Skyr &+& Utensils
+        \\
+        \red{executable} && \orange{source} && \red{executable} &&
+                                                                   \comment{links}(executable too)
+        \\
+        R && \texttt{main.c} && C compiler && Deps. (libblas, etc.)
+        } \uncover<3->{
+        \\ \\
+        \hline
+        \\
+        R@4.1.1 &$\longleftarrow$& source\orange{@4.1.1} &+& executable\red{@A} &+& links\comment{@C}
+        \\
+        \uncover<5->{$\left|\right| ?$}
+        \\
+        \uncover<4->{R@4.1.1 &$\longleftarrow$& source\orange{@4.1.1} &+& executable\red{@B} &+& links\comment{@D}}
+        }
+      \end{tabular}
+    \end{center}
+    \uncover<6->{
+  \item Too many combinations to have the same environment on different
+    machines
+    \highlight{when something is going wrong,
+      it is hard to say from where it comes}
+    \begin{center}
+      is it the environment? is it the analysis? something else?
+    \end{center}
+    }
+  \end{itemize}
+  \uncover<7->{
+  \highlight{Conclusion}: Tools allowing to \emph{capture the \comment{environment}} (= \orange{@4.1.1}, \red{@A}, \comment{@C})
+  }
+
+\end{frame}
+
+
+\begin{frame}[fragile]
+  \begin{itemize}
+  \item<1-> Alice says she uses R@4.1.1
+    \begin{semiverbatim}
+  alice@laptop\$ install r\orange{@4.1.1} \uncover<5->{\comment{# gcc-toolchain}\red{@7.5.0}}
+  alice@laptop\$ R --version
+  R version \orange{4.1.1} (2021-08-10) -- "Kick Things"
+    \end{semiverbatim}
+  \item<2-> Bob runs this same version @4.1.1
+    \begin{semiverbatim}
+   bob@cluster\$ install r\orange{@4.1.1} \uncover<5->{\comment{# gcc-toolchain}\red{@9.4.0}}
+   bob@cluster\$ R --version
+  R version \orange{4.1.1} (2021-08-10) -- "Kick Things"
+    \end{semiverbatim}
+  \item<3-> but Bob does not get the same result (e.g., precision, performance, other)
+  \item<4-> \highlight{why? what is different?} both uses R\orange{@4.1.1}
+    \uncover<5->{
+    \begin{semiverbatim}
+      \orange{$\rhd$} \$ diff with-\{\red{7.5.0},\red{9.4.0}\}/lib/R/bin/exec/R
+
+       \quad \ Binary files differ
+    \end{semiverbatim}
+    \orange{$\rhd$} \ some \comment{links} (\texttt{libquadmath.so}) are at different versions
+    }
+  \end{itemize}
+ \uncover<6->{
+  \highlight{Conclusion}: Version \orange{@4.1.1} of \orange{source} is
+  \emph{not enough} for reproducing
+
+  \begin{center}
+    Reproducibility requires to capture the \comment{environment}
+  \end{center}
+}
+\end{frame}
+
+
+\begin{frame}{Concretely, just R requires a lot!}
+  %%% guix graph r-minimal | dot -Tpng -Gsize=50,25\!  -Gratio=fill -Nstyle=filled > images/r-minimal.png
+  \includegraphics[width=\textwidth]{images/r-minimal}
+\end{frame}
+
+
+\begin{frame}{Usual (soon?) published result}
+  \begin{tabular}{cc}
+    \begin{minipage}{0.7\textwidth}
+      \includegraphics[width=\textwidth]{images/figures}
+    \end{minipage}
+    &
+      \begin{minipage}{0.3\textwidth}
+        \begin{itemize}
+        \item Cytometry CyTOF: 43 parameters
+        \item zillions of events (cells)
+        \item FlowJo (cleaning)
+        \item R plus 19 packages from BioConductor
+        \end{itemize}
+    \end{minipage}
+  \end{tabular}
+\end{frame}
+
+
+\begin{frame}{How to redo this (soon?) published result}
+  \begin{center}
+    \highlight{Assuming nothing is lost and all is transparent}
+  \end{center}
+  \begin{tabular}{lclclcl}
+           && \orange{audit} && \red{opaque} && \comment{depend?}
+    \\ \hline \\
+    result &$\longleftarrow$& \orange{paper} &+& \red{data} &+& \comment{analysis}
+    \\ \\
+    data &$\longleftarrow$& \orange{protocol} &+& \red{instruments} &+& \comment{materials}
+    \\
+    analysis &$\longleftarrow$& \orange{script} &+& \red{data} &+& \fbox{\comment{environment}}
+    \\ \\ \hline
+
+  \end{tabular}
+  \begin{center}
+    \comment{environment} = collection of packages
+  \end{center}
+  \begin{tabular}{lclclcl}
+    % environment &$\longleftarrow$& \orange{source} &+& \red{builder} (package) &+& packages
+    % \\
+    package &$\longleftarrow$& \orange{source} &+& \red{executable} &$\Big($+& others packages$\Big)$
+  \end{tabular}
+
+  \uncover<2->{
+    Alice says she uses \texttt{R@4.1.1} with \texttt{CATALYST@1.16.2} from
+    Bioconductor means:}
+  \uncover<3->{
+  \begin{itemize}
+  \item \texttt{R}: 40 input packages and 40 build packages (but 408
+    closure packages)
+  \item \texttt{CATALYST}: 27 input packages and 48 build packages
+    \\ \hfill (but 907 closure packages)
+  \end{itemize}
+  }
+\end{frame}
+
+
+\begin{frame}{Redo data is complicated}
+  \vspace{-1.35cm}
+  \begin{center}
+    \includegraphics[width=\textwidth]{images/pipe}
+  \end{center}
+\end{frame}
+
+
+\begin{frame}{Redo analysis: use Guix!}
+
+  \begin{itemize}
+  \item<1-> Alice lists the packages with the file
+    \orange{\texttt{requirements.scm}}
+    \only<1>{
+      \begin{semiverbatim}
+(specifications->manifest
+
+\quad (list
+
+\quad\quad "r"
+
+\quad\quad "r-catalyst"
+
+\quad\quad "r-flowcore"))
+      \end{semiverbatim}
+
+    }
+  \item<2-> Alice describe her current state
+    \begin{semiverbatim}
+  alice@laptop\$ guix describe
+
+  Generation 65	Aug 16 2021 20:42:44	(current)
+
+  \quad guix \comment{a9eb969}
+
+\quad\quad    repository URL: https://git.savannah.gnu.org/git/guix.git
+
+\quad\quad    branch: master
+
+\quad\quad    commit: a9eb969bb63fc421e5cb2a699ef1f1e7c5cbd1b4
+
+  alice@laptop\$ guix describe -f channels > \comment{alice-state.scm}
+  \end{semiverbatim}
+
+  \item<3-> Bob recreates the \emph{exact} same environment as Alice
+  \begin{semiverbatim}
+      bob@cluster\$ guix time-machine -C \comment{alice-state.scm} \\
+
+\quad\quad\quad\quad\quad\quad\quad -- package -m \orange{requirements.scm}
+  \end{semiverbatim}
+  \end{itemize}
+
+  \uncover<4->{
+  \highlight{Conclusion}: All \red{executable} composing the
+  \comment{environment} are captured by the state.
+  }
+\end{frame}
+
+
+\begin{frame}{Generate containers (Docker, Singularity)}
+  \begin{itemize}
+  \item<1-> \texttt{guix time-machine} allows to rebuild the same
+    \comment{environment} from \orange{source}
+  \item<2-> Bob runs analysis on another infrastructure
+  \begin{semiverbatim}
+    bob@cluster\$ guix time-machine -C \comment{alice-state.scm} \
+
+    \quad\quad\quad\quad\quad\quad\quad
+    -- pack -f docker -m \orange{requirements.txt}
+
+    bob@IFB\$ docker load < \red{image}.tar.gz
+
+    bob@IFB\$ docker run ...
+  \end{semiverbatim}
+\end{itemize}
+
+\uncover<3->{
+\begin{center}
+  \highlight{This Docker image disappears}
+\end{center}
+}
+\begin{itemize}
+\item<4-> Later, Dan rebuilds this same Docker image
+    \begin{semiverbatim}
+     dan@laptop\$ guix time-machine -C \comment{alice-state.scm} \
+
+    \quad\quad\quad\quad\quad\quad\quad
+    -- pack -f docker -m \orange{requirements.txt}
+    \end{semiverbatim}
+  \item<5-> Dan runs on another infrastructure using the exact same tools as Alice
+    \begin{semiverbatim}
+      dan@AWS\$ docker load < \red{image}.tar.gz
+
+      dabn@AWS\$ docker run ...
+    \end{semiverbatim}
+  \end{itemize}
+  \uncover<6->{
+  $\Big($Lack real examples to ensure this scenario fully works ;-$\Big)$
+      \begin{flushright}
+      \href{https://hpc.guix.info/static/videos/atelier-reproductibilit\%C3\%A9-2021/arnaud-legrand.webm}{%
+        A. Legrand@GuixHPC2021 (video)}%
+      \href{https://hpc.guix.info/static/doc/atelier-reproductibilit\%C3\%A9-2021/arnaud-legrand-debian-docker.pdf}{%
+        (pdf)}
+    \end{flushright}
+    }
+\end{frame}
+
+
+\begin{frame}{Long-term with Software Heritage}
+  \begin{center}
+    \highlight{What happens if the package on GitHub disappears?}
+  \end{center}
+
+  \begin{semiverbatim}
+dan@workstation\$ guix install hi
+
+\red{fatal: could not read Username for 'https://github.com': No such device or address}
+
+Trying content-addressed mirror at berlin.guix.gnu.org...
+
+Trying to download from Software Heritage...
+
+\orange{SWH: found revision} e1eefd033b8a2c4c81babc6fde08ebb116c6abb8
+
+at 'https://archive.softwareheritage.org/api/1/directory/c3e538ed2de412.../'
+\end{semiverbatim}
+
+The \orange{source} of \texttt{hi} were at
+\href{https://github.com/zimoun/hello-example}%
+{\sout{https://github.com/zimoun/hello-example}}.
+
+$\Big($See Software Heritage ambassador \href{https://cupnet.net/about/}{Pierre Poulain} :-$\Big)$
+
+\begin{flushright}
+  $\Big($
+  Package defined
+  \href{https://github.com/zimoun/channel-example/blob/main/hello.scm}{\emph{here}}.
+  $\Big)$
+\end{flushright}
+
+\end{frame}
+
+
+\begin{frame}{Guix in a nutshell}
+
+  \begin{center}
+    \highlight{Tools helping in managing complexity}
+  \end{center}
+  \vfill{}
+
+  \begin{enumerate}
+  \item package manager: functional and transactional paradigm
+  \item environment manager: switch between projects
+  \item generate container: Docker, Singularity
+  \item provide tools (Scheme library) to extend for user specificities
+  \end{enumerate}
+
+  \vfill{}
+  \begin{center}
+    \highlight{(fine) Control over the dependency chain}
+  \end{center}
+
+  \vfill{}
+
+  \begin{tabular}{cll}
+  \alert{$\star\star$} & Binary reproductibility &
+    \scriptsize{(at least to track it)}\normalsize \\
+    \alert{$\star\star$} & \emph{Bootstrap} &
+    \scriptsize{(new yogurt $\leftarrow$ milk + old yogurt)}\normalsize
+  \end{tabular}
+\end{frame}
+
+
+\begin{frame}[fragile]
+  \begin{center}
+    Similar to other package manager
+  \end{center}
+
+  \begin{semiverbatim}
+    \small{
+      \comment{\# Alice}
+      guix \alert{install} foo@1.2 bar@3.4 baz@5.6       \comment{\# -m requirements.scm}
+      guix \alert{describe} -f channels > \red{alice-conf.scm}
+
+      \comment{\# Carole}
+      guix install \alert{--profile}=./with-alice foo@1.2 bar@3.4 baz@5.6
+      guix install foo@7.8 bar@9.0
+
+      \comment{\# Charlie}
+      guix package \alert{--roll-back}                   \comment{\# generations}
+
+      \comment{\# Bob}
+      guix \alert{pull --channels}=\red{alice-conf.scm}
+      guix \alert{pack} -f docker ...                    \comment{# -f squashfs}
+
+      \comment{\# Dan}
+      guix \alert{time-machine} -C \red{alice-conf.scm} -- install foo@1.2 bar@3.4 baz@5.6
+    }
+  \end{semiverbatim}
+\end{frame}
+
+
+\setbeamercolor{normal text}{fg=black,bg=white}
+\begin{frame}[plain]{The \emph{ideal} target}
+  \vspace{-0.9cm}
+  \includegraphics[width=\textwidth]{images/big-picture-3}
+\end{frame}
+\setbeamercolor{normal text}{fg=white,bg=black}
+
+
+\begin{frame}{Clusters using Guix}
+  \large{
+    \begin{tabular}{lrrl}
+      \highlight{GriCAD}&\highlight{Grenoble}:& 72-node  &(1000+ cores)\\
+      \highlight{CCIPL}&\highlight{Nantes}:& 230-node  &(4000+ cores)\\
+      \highlight{PlaFRIM Inria}&\highlight{Bordeaux}:& 120-node   &(3000+ cores)\\
+      \highlight{Max Delbrück Center}&\highlight{Berlin}:& 250-node &+ workstations \\
+      \highlight{UMC Utrecht}&:& 68-node  &(1,000+ cores)\\
+      \quad (Univ. Paris ?)&:& ?9-node? &+ 2 workstations
+    \end{tabular}
+  }
+  \begin{center}
+    \includegraphics[height=0.3\paperheight]{images/guixhpc-logo-transparent}
+
+    \url{https://hpc.guix.info}
+  \end{center}
+\end{frame}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[plain]
+  \vfill{
+    \begin{minipage}[c]{1.0\linewidth}
+      \highlight{\texttt{simon.tournier@u-paris.fr}}
+      \hfill
+      \highlight{\texttt{nicolas.vallet@inserm.fr}}
+    \end{minipage}
+    \begin{center}
+      \url{https://hpc.guix.info}
+      \\
+      \includegraphics[width=0.3\textwidth]{images/Guix-white}
+    \end{center}
+    \texttt{help-guix@gnu.org}\hfill{\alert{\url{https://guix.gnu.org}}}
+  }
+\end{frame}
+
+\begin{frame}{}
+
+  \begin{textblock}{12}(2, 8)
+    \tiny{
+      Copyright \copyright{} 2021 Simon Tournier
+      \texttt{simon.tournier@u-paris.fr}.\\
+      Copyright \copyright{} 2021 Nicolas Vallet \texttt{nicolas.vallet@inserm.fr}.\\[3.0mm]
+      GNU Guix logo, CC-BY-SA 4.0, \url{https://gnu.org/s/guix/graphics}
+
+      GNU~Guix Reference Card under GFDL~1.3+.
+
+      Copyright of other images included in this document is held by
+      their respective owners; especially from Ludovic Courtès.
+      \\[3.0mm]
+      This work is licensed under the \alert{Creative Commons
+        Attribution-Share Alike 3.0} License.  To view a copy of this
+      license, visit
+      \url{http://creativecommons.org/licenses/by-sa/3.0/} or send a
+      letter to Creative Commons, 171 Second Street, Suite 300, San
+      Francisco, California, 94105, USA.
+      \\[2.0mm]
+      At your option, you may instead copy, distribute and/or modify
+      this document under the terms of the \alert{GNU Free Documentation
+        License, Version 1.3 or any later version} published by the Free
+      Software Foundation; with no Invariant Sections, no Front-Cover
+      Texts, and no Back-Cover Texts.  A copy of the license is
+      available at \url{https://www.gnu.org/licenses/gfdl.html}.
+      \\[2.0mm]
+      % Give a link to the 'Transparent Copy', as per Section 3 of the GFDL.
+      The source of this document is available from
+      \url{https://git.sv.gnu.org/cgit/guix/maintenance.git}.
+      \url{TODO}.
+    }
+  \end{textblock}
+\end{frame}
+
+
+\begin{frame}{Container is a smoothie}
+
+  \begin{itemize}
+  \item Container = a binary box that stores (captures) all the executables
+  \item How to generate one?\\
+    \hfill For instance, \texttt{Dockerfile} based on some Linux distribution
+  \item What happens if this binary container is lost?  Can I rebuild it?\\
+    \hfill The answer is no, you cannot!
+
+    Well, require a lot of hard and low-level work.
+    \begin{flushright}
+      \href{https://hpc.guix.info/static/videos/atelier-reproductibilit\%C3\%A9-2021/arnaud-legrand.webm}{%
+        A. Legrand@GuixHPC2021 (video)}%
+      \href{https://hpc.guix.info/static/doc/atelier-reproductibilit\%C3\%A9-2021/arnaud-legrand-debian-docker.pdf}{%
+        (pdf)}
+    \end{flushright}
+  \end{itemize}
+
+  \bigskip
+
+  \highlight{Conclusion 1}: Container is \highlight{useful} to move binaries from one place to another
+
+  \medskip
+
+  \highlight{Conclusion 2}: Container is \highlight{not the solution} for the Reproducibility Crisis\\
+  \hfill (= run the same analysis on different machines at different moments)
+
+\end{frame}
+
+\end{document}
+
+% Local Variables:
+% coding: utf-8
+% comment-start: "%"
+% comment-end: ""
+% ispell-local-dictionary: "french"
+% End:
