Re: Why is the RDF-star working group standardising RDF 1.2 and SPARQL 1.2?

On Fri, 27 Jan 2023 at 10:50, Antoine Zimmermann <antoine.zimmermann@emse.fr>
wrote:

> This is an email I have been wanting to write for a long time.
> The subject is a rhetorical question, please do not answer it out of the
> context of this email.
>
> RDF-star is undeniably a success in terms of adoption by companies and
> various implementers. It is, for sure, improving the data management in
> triplestores. A community group crystallised the specification so that
> it could go to standardisation.
>
> But instead of standardising RDF-star and SPARQL-star as new standards
> on top of RDF and SPARQL, it is trying to squeeze it into RDF and SPARQL
> core. I will not talk much about SPARQL-star and concentrate on the RDF
> part.
>
> Now, for me, RDF-star should play a role similar to what RDF datasets
> are playing. RDF datasets exist for better data management and query
> features. They do not interfere with the way RDF works, nor with any
> technologies that go on top of RDF. However, if RDF-star becomes the new
> RDF, it very explicitly interferes with everything on top of RDF.
>
> Every implementation that relies on RDF processing would have to be
> updated, lest they fail to be interoperable any more. I know, from the
> RDF 1.1 working group, that there are implementations that require the
> assumption that there will be only blank nodes or IRIs in subject
> position. There are vendors who consider that adding support for a new
> type of things in subject position would have dramatic cost. These
> companies would need to be convinced they'll get a lot of money from
> RDF-star in order to accept to pay the cost.
>
> Then there are standards, or community specifications that rely on RDF.
> RDFa, SHACL, SWRL, N3, RIF, R2RML, etc. What is a Web Ontology Language
> for RDF-star? If OWL can be used together with embedded triples, it
> opens a lot of possibilities, causes a lot of consequences, and brings a
> lot of questions. The RDF-star semantics is not well crystallised. There
> are people even in the community group itself that do not like the final
> version of it. Me first. There isn't a consensus on how to fix it. An
> RDF-star community consensus is, I expect, possible to reach within the
> duration of this WG. However, we've open the RDF 1.2 working group,
> albeit in disguise.
>
> And there comes a big issue. With an RDF-star WG that is implicitly an
> RDF 1.2 WG (and SPARQL 1.2 WG), we must accept the RDF community at
> large to join the discussion. Enrico, for instance, was not in the CG
> and he genuinely wants to understand how things are supposed to work
> with quoted triples. The CG report is not clear about it, as it provides
> explanatory text that suggests something, while the formal semantics
> suggests otherwise. Of course, I understand Ted's frustration as the CG
> has indeed talked about the semantic issues ad nauseam. But if you want
> to standardise RDF 1.2, you have to get people from outside the CG. And
> you can't just expect that they read the 1,000 pages of discussions and
> listen to hours of audio recording of the calls (recordings that don't
> exist, by the way).
>
> Ora, in one of the earlier meetings, said he wished the work be done in
> one year. This is, I suppose, doable if the RDF-star group standardises
> RDF-star. However, 2 years at least are certainly needed to standardise
> RDF 1.2 and SPARQL 1.2, no matter how limited the charter is. And in
> this case, I have the impression that some people underestimate how big
> the charter is. There seems to be people thinking that the CG report is
> the specification that simply needs to get a stamp of approval. But even
> if there was a consensus on it, this specification has a lot of
> consequences on everything on top of RDF, especially semantically. There
> are open questions that are to be addressed by research, not by W3C WGs.
>
> For instance, RDF-star introduces a whole new set of entailment regimes.
> Is there expertise in the group about how this is going to be handled in
> the SPARQL 1.2 Entailment Regime spec? How does SPARQL-star with OWL 2
> RDF-star-based semantics regime work?
>
> There is also the issue of the education and teaching. I teach a
> Semantic Web course. Imagine I introduce RDF 1.2, with embedded triples.
> Then I talk about ontologies, SHACL, and more, and there aren't embedded
> triples anymore! I'd rather introduce RDF (1.1), SPARQL, OWL, SHACL,
> then introduce the extension, RDF-star and SPARQL-star, if I want to get
> deeper in the data management part.
>
> Here is what I would like to see:
>   - RDF-star, a data exchange model for RDF data management. It's not
> replacing RDF, it is complementary to it.
>   - SPARQL-star, a query language for RDF-star and RDF-star datasets.
>   - As far as the semantics of RDF-star is concerned, make it critically
> minimal. Just interpret embedded triples as arbitrary resources.(*) If
> someone wants to do more reasoning, they can just invent a semantic
> extension.
> This way, just like RDF datasets define a data model on top of RDF
> without replacing it, with SPARQL a query language for this model, we
> would have RDF-star as a data model on top of RDF with a query language
> for it, mainly for data management purposes, but which does not preclude
> other usages, just like RDF datasets can be used for many things beyond
> partitioning graphs. Then there would be no discrepancy between SHACL
> and RDF, OWL and RDF, RDFa and RDF, and no need to define SPARQL-star
> entailment regimes. SPARQL Service description could be updated to be
> able to mention that a system supports SPARQL-star.
>
>
> Now, I am conscious that this does not help at all going forward in the
> direction of the charter, but I needed to say it, and I'd better say it
> early.
>

I have to say I was also surprised to read this.

If RDF itself is going to be radically updated, RDF Star is only one
consideration.

I believe the counter argument is that updating everything to support RDF
Star was mentioned and implied in the Charter.

However, my sense was that the general proposal came across as one to
augment/extend RDF, rather than "be" the latest current version of RDF.

Dan



>
> (*) RDF-star basic semantics would be defined on any RDF-entailment
> regime by adding a mapping IT from embedded triples to the set of
> resources IR. Under this basic semantics, embedded triples simply act as
> distinct names, as if they were IRIs. This does not preclude extensions
> where the internal structure of the embedded triples makes a difference.
> --
> Antoine Zimmermann
> ISI - Institut Henri Fayol
> École des Mines de Saint-Étienne
> 158 cours Fauriel
> 42023 Saint-Étienne Cedex 2
> France
> Tél:+33(0)4 77 42 66 03 <+33%204%2077%2042%2066%2003>
> https://www.emse.fr/~zimmermann/
>
>