diff --git a/talks-public/2019-04-03-RDA-WG/2019-04-03_RDA-WG.org b/talks-public/2019-04-03-RDA-WG/2019-04-03_RDA-WG.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: Software Source Code Identification
+#+SUBTITLE: Working Group
+#+AUTHOR: Roberto Di Cosmo
+#+EMAIL: roberto@dicosmo.org @rdicosmo @swheritage
+#+BEAMER_HEADER: \date{April 25nd, 2019}
+#+BEAMER_HEADER: \title[www.softwareheritage.org]{Identifiers for Digital Objects}
+#+BEAMER_HEADER: \author[Roberto Di Cosmo \hspace{5em} www.dicosmo.org]{{\bf Roberto Di Cosmo}, Daniel Katz, Martin Fenner}
+# #+BEAMER_HEADER: \setbeameroption{show notes on second screen}
+#+BEAMER_HEADER: \setbeameroption{hide notes}
+#+KEYWORDS: software heritage legacy preservation knowledge mankind technology
+#+LATEX_HEADER: \usepackage{tcolorbox}
+#
+# 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: \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}}
+* Introduction
+** Working group key facts
+*** Spawned from
+    Software Source Code Interest Group
+*** Co-chairs
+    - Roberto Di Cosmo
+    - Daniel Katz
+    - Martin Fenner
+*** Objectives
+    - bring together people involved/interested in software identification
+    - produce concrete recommendations for the academic community
+*** 
+    Online document: http://bit.ly/rda13scidwg please register there
+#+INCLUDE: "../../common/modules/rdc-bio.org::#main" :only-contents t :minlevel 2
+* Setting the stage
+** Software is Knowledge
+  :PROPERTIES:
+  :CUSTOM_ID: softwareknowledge
+  :END:
+*** Software is /an essential component/ of modern scientific research  :B_picblock:
+    :PROPERTIES:
+    :BEAMER_opt: pic=papermountain,width=.25\linewidth
+    :BEAMER_env: picblock
+    :BEAMER_act: +-
+    :END:      
+Top 100 papers (Nature, October 2014)\\
+#+BEGIN_QUOTE
+[...] the vast majority describe experimental methods or sofware that have become essential in their fields.\\
+#+END_QUOTE
+http://www.nature.com/news/the-top-100-papers-1.16224
+** The source code is essential!
+  :PROPERTIES:
+  :CUSTOM_ID: thesourcecode
+  :END:
+   #+LATEX: \includegraphics[width=.10\linewidth]{software.png}
+#+BEGIN_QUOTE  
+ “The source code for a work means the preferred form of the work for making modifications to it."
+   \hfill GPL Licence
+#+END_QUOTE
+#+Beamer: \pause
+*** 
+    :PROPERTIES:
+    :BEAMER_env: block
+    :BEAMER_act: +-
+    :END:
+#+latex:    \begin{center} Hello World \end{center}
+*** Program (excerpt of binary) 			      :B_block:BMCOL:
+    :PROPERTIES:
+    :BEAMER_col: 0.5
+    :BEAMER_env: block
+    :BEAMER_act: +-
+    :END:
+#+begin_src hex :exports code
+  4004e6: 55             
+  4004e7: 48 89 e5       
+  4004ea: bf 84 05 40 00 
+  4004ef: b8 00 00 00 00 
+  4004f4: e8 c7 fe ff ff 
+  4004f9: 90             
+  4004fa: 5d             
+  4004fb: c3             
+#+end_src
+*** Program (source code) 				      :B_block:BMCOL:
+    :PROPERTIES:
+    :BEAMER_col: 0.55
+    :BEAMER_env: block
+    :BEAMER_act: +-
+    :END:
+
+#+begin_src c :exports code
+/* Hello World program */
+
+#include<stdio.h>
+
+void main()
+{
+    printf("Hello World");
+}
+#+end_src
+** Software Source Code is /special/
+  :PROPERTIES:
+  :CUSTOM_ID: softwareisdifferent
+  :END:
+*** Harold Abelson, Structure and Interpretation of Computer Programs
+    /“Programs must be written for people to read, and only incidentally for machines to execute.”/
+
+*** Quake 2 source code (excerpt)			      :B_block:BMCOL:
+    :PROPERTIES:
+    :BEAMER_col: 0.45
+    :BEAMER_env: block
+    :END:
+   #+LATEX: \includegraphics[width=\linewidth]{quake-carmack-sqrt-1.png}
+   # smart efficient implementation of 1/sqrt(x) on a CPU without special support
+*** Net. queue in Linux (excerpt)                             :B_block:BMCOL:
+    :PROPERTIES:
+    :BEAMER_col: 0.45
+    :BEAMER_env: block
+    :END:
+   #+LATEX: \includegraphics[width=\linewidth]{juliusz-sfb-short.png}
+   # Juliusz implementation of stochastic fair blue in the Linux Kernel linux/net/sched/sch_sfb.c
+
+*** 							    :B_ignoreheading:
+    :PROPERTIES:
+    :BEAMER_env: ignoreheading
+    :END:
+*** Len Shustek, Computer History Museum
+    \hfill /“Source code provides a view into the mind of the designer.”/
+** Forgotten pillar of (Open) Science
+*** Lack of recognition 
+    :PROPERTIES:
+    :BEAMER_env: block
+    :BEAMER_COL: .5
+    :END:
+    not (yet) a first class citizen
+    - in the EOSC plan
+    - in the EU copyright reform
+    - in the scholarly works
+#+BEAMER: \pause
+*** Lack of guidance/consensus on how to
+    :PROPERTIES:
+    :BEAMER_env: block
+    :BEAMER_COL: .5
+    :END:
+    - choose a license
+    - cite a software project
+    - relate to industry best practices
+    - make source code FAIR(*)
+#+BEAMER: \pause
+*** :B_ignoreheading:
+    :PROPERTIES:
+    :BEAMER_env: ignoreheading
+    :END:
+*** Lack of basic prerequisites to reproducibility
+    See a discussion in \url{annex.softwareheritage.org/talks/2018/2018-09-17-STScI_public.pdf} 
+    
+** Interest in (research) software is raising
+*** A wealth of activities in academia
+    - artifact evaluation :: \mbox{}\\
+      now commonplace in CS conferences
+    - reproducible research :: \mbox{}\\
+      hot area of interest (jury still out on how to really do this)
+    - software archival :: \mbox{}\\
+      publishers, open access portals, propose their services
+    - academic credit :: \mbox{}\\
+      research software authors want recognition
+#+BEAMER: \pause
+*** Identifiers
+    \hfill for all the above, proper *identifiers* are needed
+** Challenges for academia
+*** Accept the complexity: software is /special/
+     - made by humans for humans: copyright law applies!
+     - not (just) data: you may have a nice hammer, but software is not a nail
+#+BEAMER: \pause
+*** Be humble: industry, developers, communities have been there
+    do not
+     - reinvent the wheel
+     - diverge from COPs
+#+BEAMER: \pause
+*** Let's start from ...
+    \hfill identifiers
+* Identifying software source code
+** Fragmented landscape
+*** Academic initiatives :B_block:
+    :PROPERTIES:
+    :BEAMER_env: block
+    :BEAMER_COL: .6
+    :END:
+    - Force 11 Software Citation Principles WG
+    - Freya EU project
+    - OpenAire EU project
+    - Publisher offerings
+    #+BEAMER: \pause
+*** Industry initiatives :B_block:
+    :PROPERTIES:
+    :BEAMER_env: block
+    :BEAMER_COL: .4
+    :END:
+    - NSRL (NIST)
+    - SPDX (Linux Foundation)
+    - SWID (ISO Standard)
+    - ...
+    #+BEAMER: \pause
+*** :B_ignoreheading:
+    :PROPERTIES:
+    :BEAMER_env: ignoreheading
+    :END:
+*** Transversal initiatives
+    - Software Heritage \hfill (disclosure: I'm leading it)
+ #+BEAMER: \pause
+** Different motivations\hfill here are a few
+*** Give credit
+    - citations :: that count for software authors
+    #+BEAMER: \pause
+*** Support reproducible research
+    - references :: to retrieve the exact version of a software artefact used in a research
+    #+BEANER: \pause
+*** Transparency
+    - software bill of materials :: enable traceability of software artefacts
+** It is way more complex than it seems
+*** All software projects are not born equal
+**** :B_column:
+     :PROPERTIES:
+     :BEAMER_env: column
+     :BEAMER_COL: .45
+     :END:
+     - structure :: \mbox{} 
+       + monolithic
+       + composite
+     - lifetime :: \mbox{}
+       + one shot
+       + long running
+     - community :: \mbox{}
+       + single developer
+       + large community
+**** :B_column:
+     :PROPERTIES:
+     :BEAMER_env: column
+     :BEAMER_COL: .45
+     :END:
+     - authorship :: \mbox{}
+       + plurality of roles
+       + difficulty of evaluating contributions
+     - authority :: \mbox{}
+       + just the commit log
+       + top down
+       + institution
+     #+BEAMER: \pause
+*** Bottomline
+    /software citation/ is much more than ... \hfill /software identification/!
+* VALID UP TO HERE: WHAT FOLLOWS NEED TO BE REWORKED
+* Agenda
+  - Introduction and motivation (15m, done)
+  - Group work and discussion on the objectives of source code identification (20m)
+  - Conceptual framework for source code identification (15m, done)
+  - Presentation of an initial state-of-the-art in the area of software source code identification (15m)
+  - Group work on a document describing the state-of-the-art (20m)
+  - Wrap up: summary of results and next steps (10m)
+
+* The Software Heritage initiative
+#+INCLUDE: "../../common/modules/swh-goals-oneslide-vertical.org::#goals" :minlevel 2
+** A principled infrastructure \hfill \url{http://bit.ly/swhpaper}
+   #+latex: \begin{center}
+   #+ATTR_LATEX: :width 0.5\linewidth
+   file:SWH-as-foundation-slim.png
+   #+latex: \end{center}
+   #+BEAMER: \pause
+   #+latex: \centering
+   #+ATTR_LATEX: :width \extblockscale{.7\linewidth}
+   file:growth.png
+   #+BEAMER: \pause
+*** Technology
+    :PROPERTIES:
+    :BEAMER_col: 0.34
+    :BEAMER_env: block
+    :END:
+    - transparency and FOSS
+    - replicas all the way down
+*** Content (billions!)
+    :PROPERTIES:
+    :BEAMER_col: 0.32
+    :BEAMER_env: block
+    :END:
+    - *intrinsic identifiers*
+    - facts and provenance
+*** Organization
+    :PROPERTIES:
+    :BEAMER_col: 0.33
+    :BEAMER_env: block
+    :END:
+    - non-profit
+    - multi-stakeholder
+* Looking for the right PIDs 
+  #+INCLUDE: "../../common/modules/swh-pids.org::#main" :only-contents t
+* Demo time
+** A "wayback machine" for software source code
+*** Identifiers in action
+       - *\url{http://archive.softwareheritage.org/browse}*
+* Conclusion
+** Conclusion \hfill @swheritage
+  #+BEAMER: \vspace{-1mm}
+*** 
+    - there are many systems of identifiers
+    - DIOs and IDOs cater to different needs
+    - IDOs enable *integrity* and *no middle man* properties *together*
+    - Software Heritage is using IDOs for billions of objects, *today*
+    - we believe IDOs are appropriate for most *digital born* content that has a *canonical* representation
+  #+BEAMER: \vspace{-1mm}
+*** Come in, we're open!
+    \url{www.softwareheritage.org} --- learn more \\
+    \url{www.softwareheritage.org/support/sponsors/} --- sponsoring info \\
+    \url{www.softwareheritage.org/support/partners} --- partners \\
+    \url{forge.softwareheritage.org} --- our own code
+    #+BEAMER: \vspace{-1mm} \flushright {\Huge Questions?} \vfill
diff --git a/talks-public/2019-04-03-RDA-WG/Makefile b/talks-public/2019-04-03-RDA-WG/Makefile
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index 0000000..68fbee7
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+++ b/talks-public/2019-04-03-RDA-WG/Makefile
@@ -0,0 +1 @@
+include ../Makefile.slides
diff --git a/talks-public/2019-04-03-RDA-WG/TODO b/talks-public/2019-04-03-RDA-WG/TODO
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+++ b/talks-public/2019-04-03-RDA-WG/TODO
@@ -0,0 +1,15 @@
+Add 
+ + use cases
+   + reproducibility
+   + citation
+ + differences --> IDO/DIO
+ 
+ + citation is a complex problem
+   + variability
+   + moderation
+   + autority
+
+ + law
+   + copyright
+
+