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Re: [OEP] Time ontology

From: Feng Pan <pan@ISI.EDU>
Date: Tue, 15 Nov 2005 14:34:40 -0800 (PST)
To: Jeremy Carroll <jjc@hpl.hp.com>
cc: public-swbp-wg@w3.org, Jerry Hobbs <hobbs@ISI.EDU>
Message-ID: <Pine.GSO.4.60.0511151425170.11103@nitro.isi.edu>

Hi Jeremy,

Thank you very much for your comments on the time ontology note! Please 
see my reply below.

> 1) duration
> 
> In the migration from DAML to OWL, the WG identified that the semantics
> of xsd:duration was unusable, and say that it *SHOULD NOT* be used.
> 
> See
> http://www.w3.org/TR/rdf-mt/
> 
> (note this text originated in WebOnt)
> 
> The SWBPD's datatype note addresses this issue
> 
> http://www.w3.org/TR/2005/WD-swbp-xsch-datatypes-20050427/#section-duration
> 
> The time ontology should be updated in line with the advice there.

Thanks for pointing out this issue. We will add a warning below our 
"durationDescriptionDataType" property, and say that:

The [RDF Semantics] Recommendation argues that xsd:duration does not have a 
well-defined value space, and should not be used. For example, it can not 
provide with an unequivocal answer to the question "How many days in a month?".

The [XML Schema Datatypes in RDF and OWL] working note from SWBPD mentions a 
proposed solution from the XQuery and XSLT Working Groups, where they derive 
two new datatypes, xdt:yearMonthDruation and xdt:dayTimeDuration from 
xsd:duration. Two corresponding properties can be straightforwardly defined in 
our ontology:

:yearMonthDurationOf
       a       owl:DatatypeProperty ;
       rdfs:domain :TemporalEntity ;
       rdfs:range xdt:yearMonthDruation .

:dayTimeDurationOf
       a       owl:DatatypeProperty ;
       rdfs:domain :TemporalEntity ;
       rdfs:range xdt:dayTimeDruation .


> 2) congo.com
> 
> W3C documents normally use the convention of taking examples from the
> reserved domain example.com, e.g. congo.example.com. This avoids
> annoying the owners of congo.com.

As mentioned in the note, Congo.com, a fictitious book-selling service site, is 
an example used in OWL-S. In order to be consistent with OWL-S, we will have to 
continue using it until OWL-S changes it to congo.example.com.


> 3) URIs versus qnames
> 
> Code such as <tz-us:EST> is incorrect in N3.
> Either use tz-us:EST, with some indication somewhere that tz-us is being
> used as a namespace prefix, possibly giving its namespace URI, or at
> least saying somthing about the namespace.
> Or give a full URI e.g. <http://example.com/tz/us#EST>

The N3 code was generated by Protege from the original OWL code in RDF/XML. 
Yes, I think you are right. <tz-us:EST> should be tz-us:EST. We will correct 
this and other similar syntax errors in the note.

As mentioned in the note after its first use, the namespace tz-us points to our 
US time zone data [11].

[11] http://www.isi.edu/~pan/damltime/timezone-us.owl

Thanks!

Feng
Received on Tuesday, 15 November 2005 22:49:49 GMT

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