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Re: RDF-ISSUE-25 (Deprecate Reification): Should we deprecate (RDF 2004) reification? [Cleanup tasks]

From: William Waites <ww@styx.org>
Date: Sat, 9 Apr 2011 11:41:46 +0200
To: Sandro Hawke <sandro@w3.org>
Cc: Richard Cyganiak <richard@cyganiak.de>, Ivan Herman <ivan@w3.org>, Eric Prud'hommeaux <eric@w3.org>, David Wood <dpw@talis.com>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-ID: <20110409094146.GA85740@styx.org>
* [2011-04-08 15:29:40 -0400] Sandro Hawke <sandro@w3.org> écrit:

] Also, people are likely to reinvent
] it unless we can clearly explain why it's a bad idea -- or accurately
] describes the problems it causes.

What of the use of reification to emulate n-ary (where n != 2)
predicates? This is actually relatively common. The actual
terms aren't rdf:{Statement,subject,predicate,object} but the shape is
the same and in those cases it is not possible to express what they 
are trying to express without reification.

An example from the Organisation Ontology,

  [] a org:Membership;
      org:member <http://www.amberdown.net/rdf/foaf.rdf#der> ;
      org:organization <http://www.epimorphics.com/public/org#epimorphics> ;
      org:role eg:ctoRole;
      org:memberDuring [a owlTime:Interval; owlTime:hasBeginning [
                        owlTime:inXSDDateTime "2009-11-01T09:00:00Z"^^xsd:dateTime]] .

This is a kind of 4-ary predicate where we have the subject (der)
object (eopmorphics), and two adverbs (eg:ctoRole, a time window) and
the verb/predicate is implied by the type. If it were possible to
express this as a normal binary predicate I'm sure they would have.

So is the proposal to deprecate this usage baked into the base
language whilst accepting that people will definitely reinvent it
where things cannot be directly expressed in terms of flat triples?

Cheers,
-w
-- 
William Waites                <mailto:ww@styx.org>
http://river.styx.org/ww/        <sip:ww@styx.org>
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Received on Saturday, 9 April 2011 09:42:14 GMT

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