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

From: Ivan Herman <ivan@w3.org>
Date: Sat, 9 Apr 2011 11:51:11 +0200
Cc: Sandro Hawke <sandro@w3.org>, Richard Cyganiak <richard@cyganiak.de>, Eric Prud'hommeaux <eric@w3.org>, David Wood <dpw@talis.com>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <C50FA758-AC47-4C34-B403-57B450A9DEB7@w3.org>
To: William Waites <ww@styx.org>
William,

I must admit I do not understand what this has to do with reification. Yes, the model you describe is fairly common and, to take an even more widely used example, it is the same pattern as the one used for a foaf:Person.

I seem to miss something here.

Ivan

On Apr 9, 2011, at 11:41 , William Waites wrote:

> * [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>
> F4B3 39BF E775 CF42 0BAB  3DF0 BE40 A6DF B06F FD45


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Ivan Herman, W3C Semantic Web Activity Lead
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Received on Saturday, 9 April 2011 09:50:55 GMT

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