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Re: RDF Extensibility

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 6 Jul 2010 16:11:19 -0500
Cc: Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-Id: <18E52FC0-6E07-4F68-83D2-38BF6AA288EC@ihmc.us>
To: Dan Brickley <danbri@danbri.org>

On Jul 6, 2010, at 10:03 AM, Dan Brickley wrote:

> 2010/7/6 Jiří Procházka <ojirio@gmail.com>:
>> On 07/06/2010 03:35 PM, Toby Inkster wrote:
>>> On Tue, 6 Jul 2010 14:03:19 +0200
>>> "Michael Schneider" <schneid@fzi.de> wrote:
>>>
>>>> So, if
>>>>
>>>>     :s "lit" :o .
>>>>
>>>> must not have a semantic meaning, what about
>>>>
>>>>     "lit" rdf:type rdf:Property .
>>>>
>>>> ? As, according to what you say above, you are willing to allow for
>>>> literals in subject position, this triple is fine for you
>>>> syntactically. But what about its meaning? Would this also be
>>>> officially defined to have no meaning?
>>>
>>> It would have a meaning. It would just be a false statement. The
>>> same as the following is a false statement:
>>>
>>>       foaf:Person a rdf:Property .
>>
>> Why do you think so?
>> I believe it is valid RDF and even valid under RDFS semantic  
>> extension.
>> Maybe OWL says something about disjointness of RDF properties and  
>> classes
>> URI can be many things.
>
> It just so happens as a fact in the world, that the thing called
> foaf:Person isn't a property. It's a class.

The world doesn't have facts like that in it. Classes and properties  
are intellectual constructs, not the stuff of reality. Hell, if a  
particle can be a wave, then surely a class can be a property. Anyway,  
RDF doesn't make logical a priori rulings about these kind of  
metaphysical segregations. For example, xsd:Number is a class, a  
property and an individual in RDF.

Pat

>
> Some might argue that there are no things that are simultaneously RDF
> classes and properties, but that doesn't matter for the FOAF case. The
> RSS1 vocabulary btw tried to define something that was both,
> rss1:image I think; but this was a backwards-compatibility hack.
>
> cheers,
>
> Dan
>
>

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Received on Tuesday, 6 July 2010 21:12:21 UTC

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