W3C home > Mailing lists > Public > semantic-web@w3.org > January 2010

Re: Requirements for a possible "RDF 2.0"

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 18 Jan 2010 10:59:26 -0600
Cc: semantic-web@w3.org
Message-Id: <F22ACD57-AC3B-4D8E-A6BC-681923CC5F3F@ihmc.us>
To: Kjetil Kjernsmo <kjetil@kjernsmo.net>

On Jan 18, 2010, at 10:28 AM, Kjetil Kjernsmo wrote:

> On Monday 18. January 2010 12:43:57 Axel Polleres wrote:
>> As for units: Is there any reason why rdf:value could not solve your
>> problem? (Although I admit that it might not be as widely used and it
>> would be good to give it more weight, or resp. refine and push best
>> practices in this direction more)
> Mainly that it has its complexity in the wrong places :-) (OK, I  
> admit, I
> had forgotten about it, I have never seen anyone use it.  
> Pragmatically,
> when something has so many use cases, yet seen very little use, it  
> is often
> because its design is flawed).
> The unit is a property of the literal, not a property of the  
> resource. By
> requiring another node, it makes it harder to query, harder to write,
> harder to read and harder to understand.

But how else would you naturally express a property of anything in  
RDF, than by writing a triple? It sounds like you want to not be using  
RDF at all :-)

> Also, how would you formulate a conversion between units (e.g. lb to  
> kg)?
> Or use derived units (e.g. watt = joule / second)? That's complexity  
> we
> should tackle, not additional triples.

In another life, I am, with many others, working on an ontology for  
measures and units, which will among other things define a large  
number of conversions and unit/dimension derivations. It is quite  
complicated to state these, and certainly well beyond the expressive  
capabilities of RDF or even OWL. I don't think that this should even  
be contemplated as an RDF built-in feature.

Pat Hayes

> Cheers,
> Kjetil
> -- 
> Kjetil Kjernsmo
> kjetil@kjernsmo.net
> http://www.kjetil.kjernsmo.net/

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Received on Monday, 18 January 2010 17:00:29 UTC

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