Re: Blog post about "Provenance in RDF-star"

Hi Antoine,

jum to the very end of your message for my reply.

On 27/01/2022 10:30, Antoine Zimmermann wrote:
> Pierre-Antoine,
>
>
> I think the description of the intended meaning of the RDF-star graphs 
> given in this post are not aligned with the formal meaning given in 
> the spec. Or, at least, that the presentation is misleading the reader 
> into misusing quoted triples for provenance (or for anything, for that 
> matter).
>
> Bare with me for a moment, as I have to place my arguments one at a 
> time before concluding.
>
> You give this example:
>
> """
> PREFIX : <http://www.example.org/>
>
> :employee38 :familyName "Smith" .
> << :employee38 :jobTitle "Assistant Designer" >> :accordingTo 
> :employee22 .
> """
>
> and say: "The intended meaning of this small RDF-star graph is: 
> “employee #38 is named Smith, and employee #22 claims that employee 
> #38 is an assistant designer”."
>
> The problem here is that a reader may conclude that, if they want to 
> say “employee #38 is named Smith, and employee #22 claims that 
> employee #38 is an assistant designer”, among other things, they can 
> just take your example and integrate it in their data set. This may 
> not be sensible, depending on what they want to say about the claim, 
> and most importantly, what they *don't* want to say about it.
>
> The issue is that, by saying "The intended meaning of this RDF-star 
> graph is [explanation]", you actually want to say "As part of the 
> intended meaning of this RDF-star graph, we have that [explanation]". 
> But this is not the full meaning of the RDF-star graph. Indeed, due to 
> the RDF-star semantics, there is additional meaning imposed by the 
> spec itself.
>
> The spec says that this RDF-star graph also carries the meaning that 
> the claim is related to the URIs ":employee38" and ":jobTitle" in a 
> specific way, and related to the string literal """"Assistant 
> Designer"^xsd:string""". If one merely wants to say that "employee 22 
> claims that employee 38 is an assistant designer", one perhaps *does 
> not* want to relate this claim to the URI ":jobTitle".
>
> When you define the intended meaning, you can say whatever you like 
> about what the URIs denote, as long as they are not among the standard 
> URIs of the spec. So you can say, for instance, that ":accordingTo" 
> denotes the relation that exists between a claim and the people who 
> make the claim. But you cannot define the intended meaning of a 
> structure of the language, like quoted triples, which is defined by 
> the spec.
>
> As an analogous example, consider standard RDF and the following 
> RDF-graph:
>
> """
> :claim1 :accordingTo "Pierre-Antoine".
> """
>
> You can say that ":accordingTo" is intended to mean the relation 
> between a claim and a person, but you cannot say that the intended 
> meaning of this triple is that ":claim1" is claimed by a person named 
> "Pierre-Antoine". Given the intention that ":accordingTo" relates a 
> claim to a person, this graph is implying that the character string 
> "Pierre-Antoine" is a person, which is absurd.[*]
>
> With such examples and explanations in your post, you are suggesting 
> the audience that they can use your RDF-star examples as templates for 
> the intended meanings you present. So you are telling the audience 
> that they can use RDF-star graphs in ways that clash with the formal 
> semantics. In other words, you are openly showing that the RDF-star 
> semantics can be safely ignored.
>
> As a consequence, I do not see how there could be, and why there 
> should be, any support for the current formal semantics of the spec. 
> Either throw it to the bin (allowing anyone to form their own 
> interpretations of what quoted triples entail) or revise it such that 
> it matches the intended meanings suggested by its authors.
>
>
>
> [*] of course, one could interpret ":accordingTo" as: "the relation 
> between a claim and the first name of a person that makes the claim". 

Yes, that's exactly what I was about to argue. I would even go further, 
and argue that many (all?) properties can be seen, from some 
perspective, as the  kind of "shortcut" that you describe above. 
Consider foaf:givenName:

     :az foaf:givenName "Antoine".

While it is convenient to conflate your given name the sequence of 
characters used to write it, this design prevents me from expressing 
some things, like for example the fact that the given name `Antoine` is 
derived from the latin name `Antonius`.

The same goes for properties that apply to quoted triples, in my opinion.

> Similarly, one could interpret ":accordingTo" as "the relation between 
> a claim that's attached to certain terms in subject, predicate, and 
> object positions, and a person who makes a claim with these terms".
> But presenting the blog post in this way would ruin the attractiveness 
> of RDF-star very much.

Could you develop why?

>
>
>
> Best,
> --AZ
>
>
>
>
>
> Le 26/01/2022 à 21:34, Pierre-Antoine Champin a écrit :
>> Dear all,
>>
>> following a discussion during our two last calls, I published a post 
>> about "Provenance in RDF-star":
>>
>> https://www.w3.org/community/rdf-dev/2022/01/26/provenance-in-rdf-star/

>>
>> quoting the intro:
>>
>>  > In this post, we present some lessons learned by the group through 
>> discussions and exchanges. This is meant to give some insight about 
>> the rationale behind RDF-star, and some guidelines about how to best 
>> use it for modeling provenance data.
>>
>> Many thanks to all the participants of the RDF-star group for their 
>> reviews and feedback on this post.
>>
>>    pa
>>
>
>