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Re: Request for feedback about RDF-star

From: Amirouche <amirouche@hyper.dev>
Date: Fri, 26 Mar 2021 15:41:51 +0100
To: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu>
Cc: Semantic Web <semantic-web@w3.org>
Message-ID: <9586345afc8987a153e2c83f035f04b4@hyper.dev>
On 2021-03-26 09:32, Pierre-Antoine Champin wrote:
> On 25/03/2021 17:59, Amirouche wrote:
>> On 2021-03-24 10:20, Pierre-Antoine Champin wrote:
>>> Dear Semantic Web community,
>>> 
>>> as you may already know, an informal "task force" has been created in
>>> the RDF-DEV Community group [1], in order to produce a specification
>>> document for RDF-star (née RDF*) [2]. RDF-star extends RDF with
>>> native support for talking about RDF statements (as an alternative to
>>> standard reification), and already has a number of implementations.
>> 
>> [...]
>> 
>>> 
>>> Thanks in advance for your feedback.
>>> 

I do not understand the last part of that sentence:

> Note also that, by definition, an RDF-star triple cannot contain
> itself and _cannot be nested infinitely_.
> 
> https://w3c.github.io/rdf-star/cg-spec/2021-02-18.html#concepts

The wording "can not be nested infinitely" imply to me that the 
reification is
limited to one level:

  1) asserted RDF triples (without embedded triples)

  2) RDF-star triples containing one or two embedded triples:

    - subject,

    inclusive or:

    - object.

My reading at '3.1.1 Grammar' specify and confirm that an embedded 
triple
may contain embedded triples : rules 27, 28, 29 [7].

[7] 
https://w3c.github.io/rdf-star/cg-spec/2021-02-18.html#turtle-star-grammar

I am not sure where my understanding is faulty.

> by definition, an RDF-star triple [...] cannot be nested infinitely.

Oh! I think that means there is no self-referential RDF-star triple.
If that is the case 'cannot be nested infinitely' is spurious wording?

What is related to embedding rdf-star triples: there is a known 
limitation of JSON
RFC specifications where the maximal depth of object embedding is not 
specified.
In RDF-star spec, I can not find a word about the maximal number of 
embedded triples
or whether that is something that is unspecified, hence should be dealt 
by every
implementations, possibly leading to different practices.


best

> 
>   best
> 
>> 
>> What I am missing?
>> 
>>>   pa
>>> 
>>> [1] https://www.w3.org/community/rdf-dev/
>>> 
>>> [2] https://w3c.github.io/rdf-star/cg-spec/
>>> 
>>> [3] http://www.w3.org/1999/02/22-rdf-syntax-ns#
>>> 
>>> [4] http://www.w3.org/TR/rdf-plain-literal/
>>> 
>>> [5] https://www.w3.org/TR/json-ld11/
>>> 
>>> [6] https://w3c.github.io/rdf-star/Minutes/2021-03-12.html#t04
>> 

-- 
Amirouche ~ https://hyper.dev
Received on Friday, 26 March 2021 14:42:07 UTC

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