Re: Presentation about reifiers and graphs

More comments:

Slide 3
(akin to literals) ==> dangerous parallel, I’d delete it.

Slide 4
...you need to identify them as concrete... ==> ...you need to associate them to concrete…

Slide 7
I guess that the first triple is syntactically wrong in (my) current understanding of Turtle.

I don’t really understand why you spend so much time on named graphs. This may lead to endless discussions we are not prepared to handle. I repeat my arguments to avoid discussions:



  1.  In the above “encoding” of a named graph, shared blank nodes labels across named graphs with a dataset MUST denote the same resource across the graphs in an RDF dataset.
  2.  On the other hand, datasets have two possible formalisations of semantics: a dataset may be interpreted as the union or as the merge of the participating named graphs, characterising exactly the sharing or not sharing of bnodes.
  3.  In Trig, a blank node label represents the same blank node throughout the TriG unique document, i.e., blank nodes sharing the same label in differently labeled graph statements are considered to be the same blank node.
  4.  In general, when named graphs in a dataset have different origin, you cannot assume that the same blank node label in different named graphs represents the same blank node.

My conclusion: these things need to be discussed, and we haven’t done it yet, and therefore I’d restrain to say that we can represent named graphs.

—e.

On 19 Sep 2024, at 06:30, Niklas Lindström <lindstream@gmail.com> wrote:

Dear all,

Thank you all for the valuable feedback! I've read all replies
(including those off-list) and much appreciate the help. (My lack of
replying is due to lack of time.) Alas, I've not yet been able to
collate and address it all (I was away on a conference), but I've
updated the presentation with some few adjustments and additions (it
is still at [1], with diffs at [2]).

The goal is to introduce reifiers, and also to compare them to graphs
and named graphs, since questions about their differences are
recurring. I want this to make sense practically, without straying
from formal definitions. As expected, there are some disputed points;
and I appreciate all help in reaching these goals. I'm sure the
presentation can be made shorter, clearer, and more inclusive.

(If I sense there is enough rough consensus on its message, I'd be
happy to present this at TPAC on behalf of the group.)

Best regards,
Niklas

[1]: <https://niklasl.github.io/rdf-docs/presentations/RDF-reifiers-1/>
[2]: <https://github.com/niklasl/rdf-docs/compare/main...dev>


On Sat, Sep 14, 2024 at 1:28 PM Niklas Lindström <lindstream@gmail.com> wrote:

Dear all,

I've drafted a presentation for the purpose of introducing reifiers
and comparing them to graphs. It's currently at:
https://niklasl.github.io/rdf-docs/presentations/RDF-reifiers-1/


Ora: you're of course free to take what you like and discard the rest
for your TPAC slides.

I tried to keep it on par with the baseline, but of course there may
be wording in there still to be agreed upon. If you see fit I can make
a PR for further collaboration in getting a version of it to
https://github.com/w3c/rdf-star-wg/tree/main/docs.


Best regards,
Niklas