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Re: Can't RDF describe collection resources?

From: Andrea Splendiani (RRes-Roth) <andrea.splendiani@rothamsted.ac.uk>
Date: Thu, 1 Mar 2012 08:49:24 +0000
To: Ruben Verborgh <ruben.verborgh@ugent.be>
CC: "<public-rdf@w3.org>" <public-rdf@w3.org>, "<public-rdf-wg@w3.org>" <public-rdf-wg@w3.org>, W3C SWIG Mailing-List <semantic-web@w3.org>
Message-ID: <F2F1B04C-D07F-4AF8-8C97-9D80BAB9D773@rothamsted.ac.uk>
Hi,

are you talking about collections and containers ?

From: http://www.w3.org/2007/02/turtle/primer/#L2986

<http://example.org/courses/6.001>
    s:students (
        <http://example.org/students/Amy>
        <http://example.org/students/Mohamed>
        <http://example.org/students/Johann>
    ).
That seems what you are looking for. However, I think this introduces a collection object in triples, that may be not "handy" in queries. I'm not sure how much collections are used: i didn't see them often.

ciao,
Andrea



Il giorno 01/mar/2012, alle ore 07.28, Ruben Verborgh ha scritto:

> Dear Semantic Web enthousiasts,
> 
> Suppose we have a Web application for blogging:
> - /posts/35 is a blog post
> - /posts/35/comments are the comments to that post
> - /posts/35/comments/3 is a specific comment to this post
> 
> In RDF, it is straightforward to make the relation between the blog post and a specific comment:
>  </posts/35> :hasComment </posts/35/comments/3>.
> It is also easy to describe the relation between a specific comment and all comments:
>  </posts/35/comments/4> :memberOf </posts/35/comments>.
> 
> However, how do we indicate the relationship between the blog post and *all* comments that belong to it?
> I.e., what is the relationship between </posts/35> and </posts/35/comments> ?
> 
> One could make a new predicate for that of course:
>  </posts/35/> :hasComments </posts/35/comments>.
> But then, we still have to explain the relation between :hasComments and :hasComment; and we’d have to do that for every such plural predicate.
> 
> This seems to be a fundamental problem.
> Clearly, the resource “comments on blog post 35” exists, but there doesn’t seem to be a straightforward way to describe it in RDF.
> RDF lists will not be sufficient: they could indeed explain the relation between a specific comment and all comments, but not the relation between all comments and the blog post.
> Also note that the indirect relation “_:x :hasComment _:y. _:y :memberOf _:z” is not sufficient: a blog post can have no comments, but even then it still has an (empty) comments resource.
> 
> Have you encountered this issue and how do you solve it?
> 
> Kind regards,
> -- 
> Ruben Verborgh
> http://twitter.com/RubenVerborgh
> PhD Student at Multimedia Lab – IBBT / ELIS, Ghent University, Belgium
> 
> Make your hypermedia API ready for intelligent agents via http://restdesc.org/.
> 
> 
Received on Thursday, 1 March 2012 08:50:07 GMT

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