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Re: Requirements for a possible "RDF 2.0"

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 20 Jan 2010 10:16:57 -0600
Cc: Dan Brickley <danbri@danbri.org>, Kjetil Kjernsmo <kjetil@kjernsmo.net>, semantic-web@w3.org
Message-Id: <0C904423-C1A4-4FF2-B7F2-7629B58E76C5@ihmc.us>
To: Jeremy Carroll <jeremy@topquadrant.com>

On Jan 19, 2010, at 7:57 PM, Jeremy Carroll wrote:

> Dan Brickley wrote:
>> How far can we go by overloading the existing datatyping mechanism?
>> ie. decorate literals with URIs that stand for particular encodings  
>> of
>> particular units?
> I think the answer to this question rests on the meaning of = in
>  8km = 5miles
> (pretending that the arithmetic is precise and correct)
> Conceptually I think we could have units:kilometer being a datatype  
> whose value space is distances and whose lexical space is the same  
> as xsd:decimal, and its value space would (modulo rounding) be the  
> same as units:mile but disjoint from units:squareMeter ...
> However I defer to others ...

Yes, this basically works, though the details are complicated, eg some  
scales are ordered but have no 'unit', others have no absolute zero,  
etc.. But for the basic stuff I see no reason why the current (or any  
other) datatyping scheme wouldn't work for this, I don't think it even  
would count as overloading. We designed the RDF datatype model to be  
extensible with new datatypes. You just have to say

units:kilometer rdf:type rdf:Datatype .

and then provide the API for reasoners which need the literal  
questions answered, eg what is equal to what.


> Jeremy

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Received on Wednesday, 20 January 2010 16:18:35 UTC

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