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Re: Why nested triples?

From: (wrong string) örtsch <tl@rat.io>
Date: Thu, 18 Feb 2021 20:29:10 +0100
Cc: public-rdf-star@w3.org
Message-Id: <93510D80-F490-48C8-9809-8DCF6C95B148@rat.io>
To: Olaf Hartig <olaf.hartig@liu.se>


> On 18. Feb 2021, at 15:56, Olaf Hartig <olaf.hartig@liu.se> wrote:
> 
> Hi Antoine,
> 
> On torsdag 18 februari 2021 kl. 15:02:11 CET Antoine Zimmermann wrote:
>> The RDF-star syntax allows for arbitrary nesting of triples like so:
>> 
>> << :s :p << << :a :b :c >> :y :z >> a :nesting .
>> 
>> Why is it so, why is it useful/needed?
>> There are no examples of nested triples. There are no justifications in
>> the spec for allowing this. As far as I know, there are no examples in
>> the past documents that defined RDF*. I did not see any use cases
>> discussed for them.
> 
> How's about something like the following?
> 
> :charlie :claims << :alice :claims <<:bob :age 23>> >> .
> 
> 
>> However, I have seen discussions that may serve as counter arguments:
>> when asked why embedded triples are limited to single triples rather
>> than sets of triples, it has been answered that RDF* is used to model
>> property-graph-like annotations that only concern one edge at a time. In
>> this case, nested triples should not be allowed, using the same
>> arguments (as far as I know, it is not possible to nest edge-annotations
>> in property graph systems).
>> 
>> Nesting makes parsers more complicated, makes it more difficult to
>> define the semantics of the data model as well as of the query language.
>> 
>> If some use cases justify nested triples, then why not use cases justify
>> embedded sets of triples?
> 
> I still think that a statement about a particular triple is something else 
> than a statement about a set of triples (a.k.a. an RDF graph) that happens to 
> contain a single triple.
> 
> For use cases in which you want to have sets of triples in the subject 
> position or the object position of another triple, doesn't N3 allow you to do 
> this?

Is RDF* just a subset of N3?

Thomas

>> Also, a question to implementers: do you support nested embedded triples?
> 
> I know that Jena supports it.
> 
> Best,
> Olaf
> 
> 
Received on Thursday, 18 February 2021 19:29:26 UTC

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