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Re: Subjects as Literals

From: Henry Story <henry.story@gmail.com>
Date: Wed, 7 Jul 2010 00:04:51 +0200
Cc: Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-Id: <15AEF4ED-EFAA-4B49-9056-67F26F04F602@gmail.com>
To: Antoine Zimmermann <antoine.zimmermann@deri.org>

On 6 Jul 2010, at 21:57, Antoine Zimmermann wrote:

> I'd like to apologize in advance for being sarcastic, especially since I have really nothing against Henry... ;)
> 
> 
> Le 06/07/2010 19:45, Henry Story a écrit :
>> 
>> This would be possible to say. The problem is that there would be no
>> way on earth that anyone could come to an agreement as to what kind
>> of property "lit" was. Everyone could make up defend their choice. And
>> where there is no right or wrong, there is no meaning. Hence the above
>> is undecidable.
>> 
>> What is the difference between the above and
>> 
>>    foaf:knows a rdf:Property .
> 
> What is the difference between the above and
> 
> 	foaf:lit a rdf:Property .
> 
> Well, we can dereference it and /not/ find out what it means.

In that case indeed you don't know much about what type of property it is. In fact 
if you can never derference it, then there are bound to be issues of who is correct about its meaning. 

I could add if you never dereferenced it, how do you know that foaf:lit is a property? You could say that it was, and I could say that it was not: how would an impartial observer come to judge on the issue?

With foaf:lit it is clear that the canonical determination of its meaning should be set by the owner of the xmlns.com domain. This does not mean that there cannot be exceptions that would make us decide otherwise. Say if xmlns.com was hacked, taken over by some pirates, or if the content was changed in a way that broke either an explicit or implicit licence that was widely accepted. The point is that there is a procedure that can be followed to understand what is right and wrong about the meaning of what foaf:lit means.

> This is possible to say. The problem is that there is no way on earth that anyone can come to an agreement as to what kind of property foaf:lit is.

I disagree. As shown above: the xmlns.com domain does help identify some agency that is responsible for names coined in that domain.

This is not and cannot be the case of pure string literals such as "lit". Those are defined by the RDF semantics as strings, and there is no way anyone else's interpretation of them as a literal can trump anyone else's. 

> Everyone can make up defend their choice. And where there is no right or wrong, there is no meaning. Hence, the above is undecidable.

This does not follow. But thanks for allowing me to clarify the difference
between URLs and pure string literals.

> And therefore, URIs as subjects should be disallowed... ;)

You can keep using URIs as subjects :-)

Henry


> 
>> Well we can dereference foaf:knows to find out what it means. This is
>> the canonical way to find it's meaning, and is the initial procedure we
>> should use to arbitrate between competing understandings of its meaning.
>> 
>> 	Henry
>> 
> 
> Cheers,
> -- 
> Antoine Zimmermann
> Post-doctoral researcher at:
> Digital Enterprise Research Institute
> National University of Ireland, Galway
> IDA Business Park
> Lower Dangan
> Galway, Ireland
> antoine.zimmermann@deri.org
> http://vmgal34.deri.ie/~antzim/
Received on Tuesday, 6 July 2010 22:05:23 UTC

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