diff --git a/talks-public/2021-01-27-Pidapalooza/2021-01-27-Pidapalooza.org b/talks-public/2021-01-27-Pidapalooza/2021-01-27-Pidapalooza.org
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+#+COLUMNS: %40ITEM %10BEAMER_env(Env) %9BEAMER_envargs(Env Args) %10BEAMER_act(Act) %4BEAMER_col(Col) %10BEAMER_extra(Extra) %8BEAMER_opt(Opt)
+#+TITLE: Intrinsic identifiers
+#+SUBTITLE: A digital fingerprint identifying software source code
+#+AUTHOR: Roberto Di Cosmo
+#+EMAIL: roberto@dicosmo.org @rdicosmo @swheritage
+#+BEAMER_HEADER: \date[January 29th, 2020]{January 29th, 2020\\[-1em]}
+#+BEAMER_HEADER: \title[The SWHID intrinsic identifier for software]{Intrinsic identifiers and the SHWID}
+#+BEAMER_HEADER: \author[Roberto Di Cosmo~~~~CC-BY 4.0]{Roberto Di Cosmo\\[1em]}
+#+KEYWORDS: software heritage legacy preservation knowledge mankind technology
+#+LATEX_HEADER: \usepackage{tcolorbox}
+#+LATEX_HEADER: \definecolor{links}{HTML}{2A1B81}
+#+LATEX_HEADER: \hypersetup{colorlinks,linkcolor=,urlcolor=links}
+#
+# prelude.org contains all the information needed to export the main beamer latex source
+# use prelude-toc.org to get the table of contents
+#
+
+#+INCLUDE: "../../common/modules/prelude-toc.org" :minlevel 1
+
+
+#+INCLUDE: "../../common/modules/169.org"
+
+# +LaTeX_CLASS_OPTIONS: [aspectratio=169,handout,xcolor=table]
+#+LATEX_HEADER: \usepackage{bbding}
+#+LATEX_HEADER: \usepackage{tcolorbox}
+#+LATEX_HEADER: \DeclareUnicodeCharacter{66D}{\FiveStar}
+
+
+#
+# If you want to change the title logo it's here
+#
+# +BEAMER_HEADER: \titlegraphic{\includegraphics[width=0.7\textwidth]{SWH-logo}}
+
+# aspect ratio can be changed, but the slides need to be adapted
+# - compute a "resizing factor" for the images (macro for picblocks?)
+#
+# set the background image
+#
+# https://pacoup.com/2011/06/12/list-of-true-169-resolutions/
+#
+#+BEAMER_HEADER: \pgfdeclareimage[height=90mm,width=160mm]{bgd}{swh-world-169.png}
+#+BEAMER_HEADER: \setbeamertemplate{background}{\pgfuseimage{bgd}}
+#+LATEX: \addtocounter{framenumber}{-1}
+
+* Extrinsic and Intrinsic identifiers in a nutshell
+** Extrinsic identifiers
+   \vspace{-.4em}
+*** The Identifier has no /per se/ relation with the designated Object
+    A /register/ keeps the correspondence between the identifier and the object
+    - pre-internet era :: passport number, social security number, ISBN, ISSN, etc.
+    - internet era :: DOI, Handle, Ark, PURLs, RRID, etc.\pause
+*** A word about the /Persistent/ adjective in Persistent Identifiers
+    - this technology /cannot guarantee/ persistence by itself! \pause Example:
+      #+ATTR_LATEX: :width .4\linewidth
+****       
+     :PROPERTIES:
+     :BEAMER_COL: .4
+     :END:
+      file:DOI.png
+****   
+     :PROPERTIES:
+     :BEAMER_COL: .5
+     :END:
+      - DOI resolution can change
+      - content at URL can change
+      - no way for the user to notice any of these changes from the outside\\
+	\mbox{}	\pause
+****                                                        :B_ignoreheading:
+     :PROPERTIES:
+     :BEAMER_env: ignoreheading
+     :END:
+     \vspace{.4em}
+    \hfill "persistence... is a function of /administrative/ care"\hfill\mbox{}\\
+      \hfill [[https://tools.ietf.org/html/rfc3650][RFC 3650 (Handle System Overview, 2003)]]
+** Intrinsic identifiers
+*** The Identifier is derived from the designated Object
+   /No register/ needed to keep the correspondence between the identifier and the object
+   - pre-internet era :: musical notation, chemical notation (/NaCl/ is table salt)\pause
+   - internet era :: cryptographic hashes for distributed software development, Bitcoin\pause
+****       
+     :PROPERTIES:
+     :BEAMER_COL: .5
+     :END:
+    file:VCS_history_timeline.png
+****   
+     :PROPERTIES:
+     :BEAMER_COL: .5
+     :END:
+      - scientific breakthrough in the 1990's
+      - massive adoption in the 2010's
+	- 150+M repositories (GitHub, BitBucket, GitLab)
+	- 40.000.000 users
+****                                                        :B_ignoreheading:
+     :PROPERTIES:
+     :BEAMER_env: ignoreheading
+     :END:
+     \mbox{}\\
+     \pause
+     /Persistence is built-in:/ nobody can change the designated object, and get away unnoticed!\pause
+*** 
+   Good news: now easily available for you via the Software Heritage Identifiers (SWHID)!
+* Software Heritage and the SWHID
+** Software Heritage in a nutshell
+  :PROPERTIES:
+  :CUSTOM_ID: goals
+  :END:
+#+latex: \begin{center}
+#+ATTR_LATEX: :width \extblockscale{.8\linewidth}
+file:SWH-logo+motto.pdf
+#+latex: \end{center}
+*** Collect, preserve and share /all/ software source code        
+    \hfill Over 150 million repositories already, ... and counting!
+#+BEAMER: \pause
+*** Addressing the ARDC key needs for (research) software source code...
+****   
+     :PROPERTIES:
+     :BEAMER_COL: .5
+     :END:
+    - Archive :: ensure it is not lost
+    - Reference :: identify the object
+****   
+     :PROPERTIES:
+     :BEAMER_COL: .5
+     :END:
+    - Describe :: make it findable
+    - Cite :: give credit to authors
+#+BEAMER: \pause
+*** ... long term, non profit initiative with broad support
+    Academia and Government: Inria, UNESCO, CNRS, French National Open Science Fund,
+    DANS, universities...
+    Industry: Intel, Microsoft, GitHub, VMware, Societe Generale, ...
+** Getting the source code in the archive
+#+INCLUDE: "../../common/modules/swh-ardc.org::#swh-a" :only-contents t :minlevel 3
+** SWHID: the source code fingerprint
+#+INCLUDE: "../../common/modules/swh-ardc.org::#swh-r" :only-contents t :minlevel 3
+** Adoption hilights ...
+   #+INCLUDE: "../../common/modules/swh-adoption-academic.org::#adoption" :only-contents t :minlevel 3   
+** Come in, we're open!
+*** 
+    \url{https://www.youtube.com/watch?v=8nlSvYh7VpI} -- full talk\\
+    \url{www.softwareheritage.org/blog} --- learn more \\
+    \url{save.softwareheritage.org} --- save code now \\
+    \url{deposit.softwareheritage.org} --- deposit code and metadata \\
+    \url{www.softwareheritage.org/swhap} --- legacy software acquisition process \\
+#    #+BEAMER: \vspace{-1mm} \flushright {\Huge Questions?} \vfill
+
+*** References                                                      :B_block:
+    :PROPERTIES:
+    :BEAMER_env: block
+    :END:
+  #+BEGIN_EXPORT latex
+  \begin{thebibliography}{Foo Bar, 1969}
+  \footnotesize
+  \bibitem{EOSCSirs2020} EOSC SIRS Task Force
+  \newblock \emph{Scholarly Infrastructures for Research Software}
+  \newblock 2020, European Commission, https://doi.org/10.2777/28598
+  
+  \bibitem{Abramatic2018} Jean-François Abramatic, Roberto Di Cosmo, Stefano Zacchiroli\newblock
+  \emph{Building the Universal Archive of Source Code},\\
+  Communications of the ACM, October 2018
+  \href{https://doi.org/10.1145/3183558}{(10.1145/3183558)}
+  \bibitem{DiCosmo2019} Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli\newblock
+  \emph{Referencing Source Code Artifacts: a Separate Concern in Software Citation},\\
+  Computing in Science and Engineering, IEEE, pp.1-9.  \href{https://dx.doi.org/10.1109/MCSE.2019.2963148}{(10.1109/MCSE.2019.2963148)}
+  \href{https://hal.archives-ouvertes.fr/hal-02446202}{(hal-02446202)}
+  \end{thebibliography}
+  #+END_EXPORT
+
+
+* Appendix :B_appendix:
+  :PROPERTIES:
+  :BEAMER_env: appendix
+  :END:
+** 
+   \vfill
+   \centerline{\Huge Appendix}
+   \vfill
+** Mirrors
+*** Thomas Jefferson, February 18, 1791 :B_block:
+    :PROPERTIES:
+    :BEAMER_ACT:
+    :BEAMER_env: block
+    :END:      
+#+latex:  {\em
+  ...let us save what remains: not by vaults and locks which fence them
+  from the public eye and use in consigning them to the waste of time,
+  but by such a multiplication of copies, as shall place them beyond
+  the reach of accident.
+#+latex: }
+   #+BEAMER: \pause
+*** Welcoming ENEA                                                  :B_block:
+    :PROPERTIES:
+    :BEAMER_env: picblock
+    :BEAMER_OPT: pic=LogoENEAcompletoENG.png, leftpic=true, width=.7\linewidth
+    :END:
+     - first *institutional* mirror
+     - increased resilience
+     - *AI infrastructure* for researchers
+     - stepping stone to \endgraf
+       \hfill an European joint effort
+** A revolutionary infrastructure for software source code
+  #+BEAMER: \vspace{-2mm}
+*** The /graph/ of Software Development                          :B_picblock:
+    :PROPERTIES:
+    :BEAMER_env: picblock
+    :BEAMER_COL: .5
+    :BEAMER_OPT: pic=git-merkle/merkle-vertical, leftpic=true, width=.4\linewidth
+    :END:
+    All software development with its history,
+    in *a single graph* ...
+ #+BEAMER: \pause \vspace{-2mm}
+*** Reference platform for /Big Code/                            :B_picblock:
+    :PROPERTIES:
+    :BEAMER_opt: pic=universal, leftpic=true, width=.4\linewidth
+    :BEAMER_env: picblock
+    :BEAMER_COL: .5
+    :BEAMER_act:
+    :END:
+   *One uniform data structure* enables /massive/ machine learning
+   for *quality, cybersecurity*, etc.
+
+*** :B_ignoreheading:
+    :PROPERTIES:
+    :BEAMER_env: ignoreheading
+    :END:
+#+BEAMER: \pause
+*** First datasets are available!
+   - full graph of software development (~20Bn nodes, ~200Bn edges)
+     see Pietri et al., MSR 2019 https://dx.doi.org/10.1109/MSR.2019.00030
+   - MSR 2020 mining competition
+** Automation, and storage                                        :maybemove:
+   #+BEAMER: \begin{center}
+   #+BEAMER:   \mode<beamer>{\only<1>{\includegraphics[width=\extblockscale{.9\textwidth}]{swh-dataflow-merkle-listers.pdf}}}
+   #+BEAMER:   \only<2-3>{\includegraphics[width=\extblockscale{.9\textwidth}]{swh-dataflow-merkle.pdf}}
+   #+BEAMER: \end{center}
+   #+BEAMER: \pause
+   #+BEAMER: \pause
+   - full development history *permanently archived!*
+   - over 8 billions unique source files from 140+ million origins
+** Archiving /public/ code
+   #+latex: \begin{center}
+   #+ATTR_LATEX: :width 0.7\linewidth
+   file:codeetalab.png
+   #+latex: \end{center}
+#+BEAMER: \pause
+   https://code.etalab.gouv.fr
+** ENEA mirror
+*** Thomas Jefferson, February 18, 1791 :B_block:
+    :PROPERTIES:
+    :BEAMER_ACT:
+    :BEAMER_env: block
+    :END:      
+#+latex:  {\em
+  ...let us save what remains: not by vaults and locks which fence them
+  from the public eye and use in consigning them to the waste of time,
+  but by such a multiplication of copies, as shall place them beyond
+  the reach of accident.
+#+latex: }
+   #+BEAMER: \pause
+*** Welcoming ENEA                                                  :B_block:
+    :PROPERTIES:
+    :BEAMER_env: picblock
+    :BEAMER_OPT: pic=LogoENEAcompletoENG.png, leftpic=true, width=.7\linewidth
+    :END:
+     - first *institutional* mirror
+     - increased resilience
+     - *AI infrastructure* for researchers
+     - stepping stone to \endgraf
+       \hfill an European joint effort
+** The Software Heritage Acquisition Process (SWHAP)
+*** Paris Call on Software Source Code
+    “[We call to] support efforts to gather and preserve the artifacts and
+    narratives of the history of computing, while the earlier creators are still
+    alive”
+#+BEAMER: \pause
+*** SWHAP : an important step forward
+     - detailed guidelines to *curate* landmark legacy source code
+       and *archive* it on Software Heritage
+     - intense cooperation with *Università di Pisa* and *UNESCO*
+     - open to all, we'll promote it worldwide
+*** 
+    https://www.softwareheritage.org/swhap
+** A walkthrough
+   - Browse [[https://archive.softwareheritage.org][the archive]]
+   - [[https://save.softwareheritage.org][Trigger archival]] of your preferred software in a breeze
+   - Get and use SWHIDs ([[https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html][full specification available online]])
+   - Cite software [[https://www.softwareheritage.org/2020/05/26/citing-software-with-style/][with the biblatex-software style]] from CTAN
+   - Example use in a research article: compare Fig. 1 and conclusions 
+      - in [[http://www.dicosmo.org/Articles/2012-DaneluttoDiCosmo-Pcs.pdf][the 2012 version]]
+      - in [[https://www.dicosmo.org/share/parmap_swh.pdf][the updated version]] using SWHIDs and Software Heritage
+   - Example use in a research article: extensive use of SWHIDs in [[https://www.dicosmo.org/Articles/2020-ReScienceC.pdf][a replication experiment]]
+   - [[https://doc.archives-ouvertes.fr/en/deposit/deposit-software-source-code/][Curated deposit in SWH via HAL]], see for example: 
+      [[https://hal.archives-ouvertes.fr/hal-02130801][LinBox]], [[https://hal.archives-ouvertes.fr/hal-01897934][SLALOM]], [[https://hal.archives-ouvertes.fr/hal-02130729][Givaro]], [[https://hal.archives-ouvertes.fr/hal-02137040][NS2DDV]], [[https://hal.archives-ouvertes.fr/lirmm-02136558][SumGra]], [[https://hal.archives-ouvertes.fr/hal-02155786][Coq proof]], ...
+   - Rescue landmark legacy software, see the [[https://www.softwareheritage.org/swhap/][SWHAP process with UNESCO]]
+** A worked example
+  #+LATEX: \centering\forcebeamerstart
+  #+LATEX: \only<1>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/merkle_1.pdf}}}
+  #+LATEX: \only<2>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/contents.pdf}}}
+  #+LATEX: \only<3>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/merkle_2_contents.pdf}}}
+  #+LATEX: \only<4>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/directories.pdf}}}
+  #+LATEX: \only<5>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/merkle_3_directories.pdf}}}
+  #+LATEX: \only<6>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/revisions.pdf}}}
+  #+LATEX: \only<7>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/merkle_4_revisions.pdf}}}
+  #+LATEX: \only<8>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/releases.pdf}}}
+  #+LATEX: \only<9>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/merkle_5_releases.pdf}}}
+  #+LATEX: \only<10>{\colorbox{white}{\includegraphics[width=\extblockscale{\linewidth}]{git-merkle/snapshots.pdf}}}
+  #+LATEX: \forcebeamerend
+
diff --git a/talks-public/2021-01-27-Pidapalooza/Makefile b/talks-public/2021-01-27-Pidapalooza/Makefile
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index 0000000..68fbee7
--- /dev/null
+++ b/talks-public/2021-01-27-Pidapalooza/Makefile
@@ -0,0 +1 @@
+include ../Makefile.slides