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Re: Can't RDF describe collection resources?

From: Ruben Verborgh <ruben.verborgh@ugent.be>
Date: Thu, 1 Mar 2012 09:22:36 +0100
Cc: Michael Hausenblas <michael.hausenblas@deri.org>, W3C SWIG Mailing-List <semantic-web@w3.org>, public-rdf-wg@w3.org, public-rdf@w3.org
Message-Id: <703D593C-4B7F-4B0F-8FC7-5D8043EAEBC7@ugent.be>
To: Rinke Hoekstra <hoekstra@few.vu.nl>
Hi Rinke,

> Also, this can be quite adequately represented using OWL property chains.

I’m not sure it can. What would this look like with the provided example?
And does it still work when there are no comments to the blog post, e.g., can I identify the relation between a blog post and the empty comments resource?



> On Mar 1, 2012 8:13 AM, "Michael Hausenblas" <michael.hausenblas@deri.org> wrote:
> Are you aware of http://sioc-project.org/ ...?
> Cheers,
>        Michael
> --
> Dr. Michael Hausenblas, Research Fellow
> LiDRC - Linked Data Research Centre
> DERI - Digital Enterprise Research Institute
> NUIG - National University of Ireland, Galway
> Ireland, Europe
> Tel. +353 91 495730
> http://linkeddata.deri.ie/
> http://sw-app.org/about.html
> On 1 Mar 2012, at 07:28, Ruben Verborgh wrote:
> 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 08:23:21 UTC

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