W3C home > Mailing lists > Public > public-rdf@w3.org > March 2012

Can't RDF describe collection resources?

From: Ruben Verborgh <ruben.verborgh@ugent.be>
Date: Thu, 1 Mar 2012 08:28:51 +0100
Message-Id: <97DC9B53-ACF8-41BA-BEAB-EC7906CB3E6B@ugent.be>
To: public-rdf@w3.org, public-rdf-wg@w3.org, W3C SWIG Mailing-List <semantic-web@w3.org>
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
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 07:29:38 UTC

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