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Re: N-ary relation and rdf star

From: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu>
Date: Tue, 5 Jan 2021 11:31:54 +0100
To: Patrick J Hayes <phayes@ihmc.us>
Cc: public-rdf-star@w3.org
Message-ID: <cd2d51e2-7300-d397-05a7-95cb38d2feab@ercim.eu>
On 05/01/2021 09:36, Patrick J Hayes wrote:

>> On Jan 4, 2021, at 8:55 PM, Jeen Broekstra <jb@metaphacts.com 
>> <mailto:jb@metaphacts.com>> wrote:
>> On Tue, 5 Jan 2021, at 01:21, Joy lix wrote:
>>> Dear All:
>>> I'm learning RDF star, what is the  difference between N-ary 
>>> relation and RDF star?
>>> N-ary relation :https://www.w3.org/TR/swbp-n-aryRelations/ 
>>> <https://www.w3.org/TR/swbp-n-aryRelations/>
>> RDF* is an extension of RDF that aims to make modeling certain kinds 
>> of n-ary relations easier.
> Really?? That is not what I have been reading up until now. RDF* 
> replaces RDF reification: what it encodes is assertions /about/ a 
> triple. Such as provenance information. That is quite different from 
> extending a triple to an n-tuple in order to encode n-ary relations.

More generally, the goal is to mimic Property Graph's ability to 
annotate arcs, which is used for many use-cases. Provenance is one of 
them, N-ary relations is another one. For example, a common example in 
Property Graphs is "Tom Hanks stars in 'Saving Private Ryan' as Captain 
Miller", which could be represented in RDF* (using the annotation syntax):

   :tom_hanks :stars_in :movie123 {| :as "Captain Miller" |}.

> Keeping things like this clear is why it is important to have a crisp 
> semantics for RDF*.

We are working on it ;) I expect to submit a new Pull Request soon...


> Pat Hayes
>> As the working group note you mention shows, there are other ways to 
>> represent such relations in RDF without needing an extension, but 
>> they all have certain drawbacks. RDF* hopes to overcome some of those 
>> drawbacks.
>>> This W3C Working Group Note hasn't been updated since 2006. Can it 
>>> still be used?
>> Yes. The approaches for modeling n-ary relations shown in that note 
>> are still as valid today as they were in 2006. It's just that RDF* 
>> gives you another option, that (hopefully, in some cases) will make 
>> things easier.
>> Kind regards,
>> Jeen
>> --
>> Dr Jeen Broekstra (he, him)
>> /principal software engineer/
>> jb@metaphacts.com <mailto:jb@metaphacts.com>
>> www.metaphacts.com <https://www.metaphacts.com/>
>> htps://www.metaphacts.com/ <https://www.metaphacts.com/>

Received on Tuesday, 5 January 2021 10:31:59 UTC

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