- From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- Date: Tue, 28 Jul 2020 00:40:18 +0200
- To: thomas lörtsch <tl@rat.io>
- Cc: Maxime Lefrançois <maxime.lefrancois@emse.fr>, "Shaw, Ryan" <ryanshaw@unc.edu>, Hugh Glaser <hugh@glasers.org>, Semantic Web <semantic-web@w3.org>
Le 27/07/2020 à 23:54, thomas lörtsch a écrit :
>
>
>> On 27. Jul 2020, at 20:56, Antoine Zimmermann <antoine.zimmermann@emse.fr> wrote:
>>
>> Le 27/07/2020 à 18:52, Maxime Lefrançois a écrit :
>>> If we imagine datatypes that encode RDF graphs,
>>
>> Ivan Herman drafted a document a while ago that does exactly that:
>>
>> https://www.w3.org/2009/07/NamedGraph.html#definition-of-graph-literals
>>
>>
>> I even think that, in some cases, it could be of some usefulness, but the kinds of use cases are so niche, and the idea of encoding RDF graphs inside literals in other RDF graphs is so disturbing to the homo semanticus that there are chances it will never get traction.
>
> For graphs that contain only one triple it’s really not very different from what RDF* does, isn’t it?
I don't pretend to have an in-depth knowledge of RDF*, but I've read the
papers specifying RDF* with sufficient attention to say that it is not
the case.
The following triple (using Ivan's specification of graph literals):
<s> <p> "<subject> <predicate> <object>"^^rdfl:GraphLiteral .
has one RDF triple. It conforms to the RDF standards.
In RDF*, this:
<s> <p> << <subject> <predicate> <object> >> .
is not an RDF triple. From one of the papers about RDF*, the previous
"triple" could be understood as syntactic sugar for a reified triple,
like so:
<s> <p> [
rdf:subject <subject>;
rdf:predicate <predicate>;
rdf:object <object>
]
but another paper says it could be interpreted differently. In any case,
the power of RDF* is probably in its accompanying query language
SPARQL*, where you can ask:
SELECT ?x WHERE {
<s> <p> << <subject> <predicate> ?x >> .
}
You can't do this with a literal, unless you use regular expressions and
filters. In any case, RDF* is a different data model, while graph
literal is just a way of using the RDF data model to include graphs as
values in the domain of discourse.
--AZ
>
> TL_
>
>>
>> —AZ
>>
>
Received on Monday, 27 July 2020 22:40:34 UTC