- From: Harry Halpin <hhalpin@ibiblio.org>
- Date: Mon, 18 Jan 2010 17:07:49 +0000
- To: Pat Hayes <phayes@ihmc.us>
- Cc: Kjetil Kjernsmo <kjetil@kjernsmo.net>, semantic-web@w3.org
On Mon, Jan 18, 2010 at 4:59 PM, Pat Hayes <phayes@ihmc.us> wrote: > > 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. Agreed. > > 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. > Well, that would probably require arithmetic, which is outside of RDF and OWL (unless OWL2 has added something I don't know about quite yet!) > 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. But how about: a b "blah blah z" as in ex:London ex:hasTemp "10 ex:Celsius" where z is a URI for a custom data-type that defines a relationship to the base XML Schema data-types? RDF needs to take syntactic sugar seriously. So, we could imagine that then we could decompose a b "blah blah z" -> a b "blah blah" AND "blah blah" rdf:value z" i.e. ex:London ex:hasTemp "10" AND "10 rdf:value ex:Celsius" Although we should of course have restrictions on data merging subjects as literals. > > Pat Hayes > > >> >> Cheers, >> >> Kjetil >> -- >> Kjetil Kjernsmo >> kjetil@kjernsmo.net >> http://www.kjetil.kjernsmo.net/ >> >> > > ------------------------------------------------------------ > IHMC (850)434 8903 or (650)494 3973 > 40 South Alcaniz St. (850)202 4416 office > Pensacola (850)202 4440 fax > FL 32502 (850)291 0667 mobile > phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes > > > > > > >
Received on Monday, 18 January 2010 17:08:18 UTC