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

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". 
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.



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
> 


-- 
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
https://www.emse.fr/~zimmermann/

Received on Thursday, 27 January 2022 09:30:48 UTC