Hi all, this is the SG19 Machine Learning meeting that will focus on graphs. Please see Phil's email update from Feb 5th on the split papers and the attachment. Thanks Phil.

Paper	Status	Pages
D9901 Overview & Introduction	Active	7
D9902 Algorithms	Active	17
D9903 Operators	Active	6
D9904 Views	Active	11
D9905 Graph Container Interface	Active	10
D9906 Graph Containers	Active	5
D9907 Adaptors	Future
D9908 Background and Terminology	Future

We can also have an update on stats.
Are there any other suggested topics?

We have finalized sg19 vice chairs  Phil Ratzloff and Andrew Lumsdaine.

We will have an SG14 meeting the day before on Wednesday to review Graph:

Topic: SG14 monthly
Time: 2nd Wednesdays 02:00 PM Eastern Time (US and Canada)
    Every month on the Second Wed,

Join from PC, Mac, Linux, iOS or Android:
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Thank you.


Michael Wong is inviting
you to a scheduled Zoom meeting.

Topic: SG19 monthly
Time: 02:00 PM Eastern Time (US and Canada)
    Every month on the Second Thu,


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Agenda:

1. Opening and introductions

The ISO Code of conduct:
https://www.iso.org/files/live/sites/isoorg/files/store/en/PUB100397.pdf

IEC Code of Conduct:

https://www.iec.ch/basecamp/iec-code-conduct-technical-work

ISO patent policy.

https://isotc.iso.org/livelink/livelink/fetch/2000/2122/3770791/Common_Policy.htm?nodeid=6344764&vernum=-2

The WG21 Practices and Procedures and Code of Conduct:
https://isocpp.org/std/standing-documents/sd-4-wg21-practices-and-procedures

1.1 Roll call of participants

1.2 Adopt agenda

1.3 Approve minutes from previous meeting, and approve publishing
 previously approved minutes to ISOCPP.org

1.4 Action items from previous meetings

2. Main issues (125 min)

2.1 General logistics

Meeting plan, focus on one paper per meeting but does not preclude other paper updates.

2024 planning
C++23 and C++26 status


* Jan 11, 2024 02:00 PM ET: Graph

* Feb 8, 2024 02:00 PM ET: Graph

* Mar 14, 2024 02:00 PM ET: Cancelled due to Tokyo 3-18-23
* Apr 11, 2024 02:00 PM ET: Stats

* May  9, 2024 02:00 PM ET: Graph

* June 13, 2024 02:00 PM ET: Embedded; St.louis 6-24-29
* July 11, 2024 02:00 PM ET: Stats
* Aug 15, 2024 02:00 PM ET: Graph
* Sep 12, 2024 02:00 PM ET: CPPCON Sept 15-20 so canceled

* Oct 10, 2024 02:00 PM ET: Stats
* Nov 14, 2024 02:00 PM ET: Cancelled Wroclaw F2F

* Dec 12, 2024 02:00 PM ET: Graph

ISO meeting status

future C++ Std meetings

2.2 Paper reviews

Review BSI Graph feedback:

As Oliver (Rosten) said "The basic premise is important, and it would be fantastic to have support for graphs in the standard."

The main items identified were:

Oliver:

- This paper is long and incomplete, it has lots of details which I think to be irrelevant, however things that are definitely relevant are missing from the paper - for example definition of graph - since people have different ideas. We need to add a mathematical perspective to the paper.

- The structure of the paper completely changed in the new revision, so now it’s hard to understand what and why they have done

- Another missing part is discussion of graph invariants

Tom (Deakin): There’s a big missing part in “Prior art” part, GraphBLAS (https://graphblas.org) eminently.

Some other things to add:

1. The electrical circuit example needs more explanation, and I think this will highlight some deep issues around representing things which are seemingly trivially graphs, as graphs in practice. In what sense is a bog-standard resistor directed? I assume the reason that the graph is directed is because current has a sign and in an undirected graph it becomes ambiguous which way the current is flowing (also you may want components like diodes). But the directed representation also has issues: "can current flow from 'Vdd'  to 'n0'?" should be immediately answerable from the properties of Vdd and its edges. There are other ways to represent an electrical circuit. One is as a directed graph but with incident edges recorded - but iiuc, this is excluded from the latest version of the paper. Alternatively, one could have a mathematical object, the name of which I actually don't know: it looks like an undirected graph, but where each partial edge has additional, unique, end-point data, as well as the common weight. Things like this are the reason why I think we need a broader group to look at this proposal (i.e. beyond SG19) and if we possibly can we should involve someone from the mathematics community. Otherwise there's a real danger we end up missing important insights.

2. My comment about the structure of the paper changing was a reference to previous comparisons with boost::graph. I'm sure these were in an earlier version, or am I misremembering? Either way, it would be very helpful to have a proper discussion of e.g. the move away from visitors.

3. Re. the definition of a graph, there needs to be a proper discussion about whether the paper's definition of graph is what some authors call a multigraph and whether it does/does not include loops. These things are mentioned, in passing, when introducing algorithms, but terminology needs to be properly established. 

4. I think we're trying to do too much in one go in this paper. I think a great first step would be to build on mdspan and try to standardize (or at least understand) what might reasonably be called an unstructured span. This could be represented as a vector of vectors or as a vector with some auxiliary storage indicating where the partitions fall. The point is that an unstructured span, with the right invariants, is an adjacency list. If we can understand unstructured span and its desirable api, I think this will be incredibly valuable guidance for what a standardized graph container might look like.

5. IIUC, this paper excludes pure connectivity graphs. These are incredibly helpful and, if I've understood correctly that they are not supported, would be a major omission. Another good reason, imo, to start with unstructured span!

6. I'm not convinced by the load api. We don't have a load api for vector etc. Moreover, would it not be preferable to have appropriate constructors?

2.2.1: ML topics

2.2.1.1 Graph Proposal Phil Ratsloff et al

Latest paper:

Here’s a link to the paper (different than the previous paper reviewed).
There are some additional updates I’m planning on making before the meeting.

https://docs.google.com/document/d/1OpH-xxRri7tJTtJJIZTYmSHkkrZJkdBwm9zJ7LqolfQ/edit?usp=sharing




P1709R3:
https://docs.google.com/document/d/1kLHhbSTX7j0tPeTYECQFSNx3R35Mu3xO5_dyYdRy4dM/edit?usp=sharing

https://docs.google.com/document/d/1QkfDzGyfNQKs86y053M0YHOLP6frzhTJqzg1Ug_vkkE/edit?usp=sharing

<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2119r0.html>

<
https://docs.google.com/document/d/175wIm8o4BNGti0WLq8U6uZORegKVjmnpfc-_E8PoGS0/edit?ts=5fff27cd#heading=h.9ogkehmdmtel
*>*

Array copy semantics:
array copy-semantics paper P1997 "Relaxing Restrictions on Arrays",
https://wg21.link/p1997

Stats feedback:

P2376R0
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2376r0.pdf>
Comments
on Simple Statistical Functions (p1708r4): Contracts, Exceptions and
Special cases Johan Lundberg

2.2.1.2 Reinforcement Learning Larry Lewis Jorge Silva

Reinforcement Learning proposal:

2.2.1.3 Differential Calculus:

https://docs.google.com/document/d/175wIm8o4BNGti0WLq8U6uZORegKVjmnpfc-_E8PoGS0/edit?ts=5fff27cd#heading=h.9ogkehmdmtel

2.2.1.4: Stats paper

P2681R0
<https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2681r0.pdf> More
Stats Functions Richard Dosselmann, Michael Wong
Current github

https://github.com/cplusplus/papers/issues/475

https://github.com/cplusplus/papers/issues/979

Stats review Richard Dosselman et al

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1708r4.pdf

Feedback from Johan Lundberg and Oleksandr Korval

https://isocpp.org/files/papers/D2376R0.pdf

P1708R3: Math proposal for Machine Learning: 3rd review

PXXXX: combinatorics: 1st Review

*> std.org/jtc1/sc22/wg21/docs/papers/2020/p1708r2
<http://std.org/jtc1/sc22/wg21/docs/papers/2020/p1708r2>*
*> above is the stats paper that was reviewed in Prague*
*> http://wiki.edg.com/bin/view/Wg21prague/P1708R2SG19
<http://wiki.edg.com/bin/view/Wg21prague/P1708R2SG19>*
*>*
*> Review Jolanta Polish feedback.*
*> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2119r0.html
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2119r0.html>*


2.2.1.4: Matrix paper

2.2.3 any other proposal for reviews?

2.3 Other Papers and proposals

P1416R1: SG19 - Linear Algebra for Data Science and Machine Learning
https://docs.google.com/document/d/1IKUNiUhBgRURW-UkspK7fAAyIhfXuMxjk7xKikK4Yp8/edit#heading=h.tj9hitg7dbtr

P1415: Machine Learning Layered list
https://docs.google.com/document/d/1elNFdIXWoetbxjO1OKol_Wj8fyi4Z4hogfj5tLVSj64/edit#heading=h.tj9hitg7dbtr

2.2.2 SG14 Linear Algebra progress:
Different layers of proposal
https://docs.google.com/document/d/1poXfr7mUPovJC9ZQ5SDVM_1Nb6oYAXlK_d0ljdUAtSQ/edit

2.5 Future F2F meetings:

2.6 future C++ Standard meetings:
https://isocpp.org/std/meetings-and-participation/upcoming-meetings

None

3. Any other business

New reflector

http://lists.isocpp.org/mailman/listinfo.cgi/sg19

Old Reflector
https://groups.google.com/a/isocpp.org/forum/#!newtopic/sg19
<https://groups.google.com/a/isocpp.org/forum/?fromgroups=#!forum/sg14>

Code and proposal Staging area

4. Review

4.1 Review and approve resolutions and issues [e.g., changes to SG's
working draft]

4.2 Review action items (5 min)

5. Closing process

5.1 Establish next agenda


5.2 Future meeting
* Jan 11, 2024 02:00 PM ET: Graph DONE

* Feb 8, 2024 02:00 PM ET: Graph

* Mar 14, 2024 02:00 PM ET: Cancelled due to Tokyo 3-18-23
* Apr 11, 2024 02:00 PM ET: Stats

* May  9, 2024 02:00 PM ET: Graph

* June 13, 2024 02:00 PM ET: Embedded; St.louis 6-24-29
* July 11, 2024 02:00 PM ET: Stats
* Aug 15, 2024 02:00 PM ET: Graph
* Sep 12, 2024 02:00 PM ET: CPPCON Sept 15-20 so cancelled

* Oct 10, 2024 02:00 PM ET: Stats
* Nov 14, 2024 02:00 PM ET: Cancelled Wroclaw F2F

* Dec 12, 2024 02:00 PM ET: Graph

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