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Fwd: status of xsd:duration in RDF

From: Ivan Herman <ivan@w3.org>
Date: Sat, 19 May 2012 17:28:46 +0200
Cc: W3C RDF WG <public-rdf-wg@w3.org>
Message-Id: <EB24F133-A47A-48C3-B852-E239CF1F8BE2@w3.org>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
Peter,

this mail arrived as a question to your question, and I would like to answer it. I think that:

- yes, duration would just be 'added' to the list but there is no planned change on the 'status' of these types regarding the RDF semantics.
- actually, though not related to duration: would the fact that XMLLiteral becomes optional mean that D-entailment would not refer to this any more? If so, does that affect OWL 2 and RIF?

Thanks

ivan 

Begin forwarded message:

> Resent-From: public-owl-wg@w3.org
> From: Michael Schneider <schneid@fzi.de>
> Subject: Re: status of xsd:duration in RDF
> Date: May 9, 2012 20:49:14 GMT+02:00
> To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
> Cc: "public-owl-wg@w3.org" <public-owl-wg@w3.org>, Ian Horrocks <ian.horrocks@cs.ox.ac.uk>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
> Archived-At: <http://www.w3.org/mid/4FAABC2A.80708@fzi.de>
> List-Id: <public-owl-wg.w3.org>
> 
> Hi Peter!
> 
> Am 09.05.2012 17:09, schrieb Peter F. Patel-Schneider:
> > Regardless of whether xsd:duration can make it into OWL 2, there is a
> > question of whether anyone in this group knows of any reason why
> > xsd:duration should not be added to RDF by the current RDF WG, aside
> > from a desire to have the datatypes in OWL match those in RDF.
> >
> > Any comments?
> 
> Two questions (with some implicit answers to your question):
> 
> 1) What other datatypes are under consideration by the RDF WG to be "added to RDF"? There are a lot of datatypes being mentioned in the original RDF standard, which were not taken into account by the OWL 2 and RIF specs, such as xsd:gYear, xsd:gMonthDay, xsd:gDay, xsd:gMonth. So, one could argue, if these datatypes are going to be added to RDF (again), why should we (the OWL WG) then care about xsd:duration? It'll be then just yet another datatype that is in RDF but not in OWL 2 and RIF.
> 
> 2) What does "adding to RDF" precisely mean? Mentioning the datatype somewhere in the spec by its name? Or making it a normative part of the RDF semantics? In RDF 1, the definitions of RDF-, RDFS- and D-interpretations only contained rdf:XMLLiteral as a normative part. There was one specific datatype map being mentioned in the chapter on D-entailment, called the "XSD datatype map" (the one with the non-OWL2 datatypes mentioned above), but it was not an official part of the semantics of any D-interpretation (as many people seem to believe), but was just a well-known datatype map, an example for how a "D" could look like (perhaps a "primus-inter-pares D", but not more). If "adding to RDF" is meant that way, then I would *not* care much, whether xsd:duration is included in the new version of the XSD datatype map or not. If, however, it is meant to become (together with its friends from the XSD datatype map) a normative part of any D-interpretation (which would be a big step from RDF 1), then I would care *much*, because any OWL 2 RDF-Based interpretation is a D-interpretation, and if all D-interpretations would include all the XSD datatypes from the RDF spec (plus, maybe, xsd:duration), this would mean that future OWL-N Full reasoners would have to support them all, which is quite a bit more than what OWL 2 Full reasoners are expected today (with possible implementation trouble here and there)! (To be mentioned: Most probably, this would then only be an issue for OWL N Full, not OWL N DL, as for current OWL 2 DL, the semantics and, in particular, the set of to-be-supported datatypes is specified independently from the RDF semantics specification).
> 
> So far from my slightly RDF-Based/OWL Full-centric point of view.
> 
> Best,
> Michael
> 
> -- 
> .........................................................
> Dipl.-Inform. Michael Schneider
> Research Scientist, IPE / WIM
> 
> FZI Forschungszentrum Informatik
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----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Saturday, 19 May 2012 15:25:27 GMT

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