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Re: status of xsd:duration in RDF

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 19 May 2012 10:38:50 -0500
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, W3C RDF WG <public-rdf-wg@w3.org>
Message-Id: <BE1404F2-3A60-4C74-8DEB-64439359B821@ihmc.us>
To: Ivan Herman <ivan@w3.org>

On May 19, 2012, at 10:28 AM, Ivan Herman wrote:

> 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?

It would refer to it, but it would be listed along with the XSD suite as being optional (part of a D) rather than built into RDF entailment. Yes, this should affect OWL and other entailment regimes which are built on RDF. I think it will make them easier, or else they are free to state that this datatype is built into OWL. Either way, something changes, if only editorial.

We could help with this by saying that semantic extensions MAY choose to treat XMLLIteral as a built-in datatype. That lets them off the hook editorially. But we should check with them.


> 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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>> Tel.: +49 721 9654-726
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>> .........................................................
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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

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Received on Saturday, 19 May 2012 15:39:26 UTC

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