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Re: Multiple rdf:type elements

From: Graham Klyne <GK@ninebynine.org>
Date: Thu, 06 Jun 2002 21:29:11 +0100
Message-Id: <5.1.0.14.2.20020606212438.03a72e60@joy.songbird.com>
To: Alan Lillich <alillich@adobe.com>
Cc: <www-rdf-interest@w3.org>

At 11:17 AM 6/6/02 -0700, Alan Lillich wrote:

>An example of an rdf:Description element containing multiple rdf:type
>elements came up in a recent discussion.  Clearly the syntax allows this,
>and any one of the rdf:type elements could be used to produce a typedNode
>form.
>
>Has there ever been any discussion about the utility or meaning of this?
>Perhaps to model multiple inheritance? Is it an oversight in the syntax?
>Should RDF implementations complain about it if they have a checking mode?

I see no problem here.  If one views a type as a representing a monadic 
predicate that the subject satisfies, then having multiple types for a 
subject seems a quite natural, reasonable and useful facility.

Example:  it is quite reasonable that some subject may be a horse, an 
animal and a means of transport.  The horse and animal properties have a 
fairly clear subclass relationship, but that's not so clear with the "means 
of transport" property.  RDF types are ideally suited for representing such 
attributes, and multiple-typing is entirely consistent and useful in this mode.

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Thursday, 6 June 2002 16:27:10 GMT

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