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Re: OWL WG LC comment for SKOS reference document [ISSUE-157]

From: Sean Bechhofer <sean.bechhofer@manchester.ac.uk>
Date: Wed, 10 Dec 2008 19:01:50 +0000
Message-Id: <5080974B-FC69-4FCE-A626-9EC97B24AC7A@manchester.ac.uk>
Cc: public-swd-wg@w3.org, public-owl-wg@w3.org
To: Peter F. Patel-Schneider <pfps@research.bell-labs.com>


Thanks for your comments on behalf of the OWL WG [1]. This is a  
response to part of these comments, marked in our issues list as  
ISSUE-157 "SKOS and OWL 2 analysis" [2]:

   The OWL WG notes that some parts of the SKOS specification and  
some examples in the reference document do not fit within OWL 2 DL  
and that thus may not be fully supported by Semantic Web tools.  The  
OWL WG presents the following analysis of the SKOS specification and  
examples, to indicate where representation capabilities beyond OWL 1  
DL are used. The OWL WG further notes that in many cases the SKOS  
specification fits within OWL 2 DL, but that the examples do not.   
The OWL WG suggests removing those examples that do not fit within  
OWL 2 DL.([from [1])

below you find our responses to the SKOS aspects that are not OWL 2  
DL compliant. As a general strategy, we have tried as much as  
possible to accommodate the alignment with OWL 2 DL. A number of  
specific points cannot be resolved at this time (see below), so we  
have decided to POSTPONE this issue.

Section: Lexical Labels
Language: OWL 2 Full
Issue: subproperty of rdfs:label
Suggestion: don't use rdfs:label

We prefer to keep the subProperty relation; however, we propose to  
change the type of the lexical label to owl:AnnotationProperty (see  
resolution of ISSUE 135 [3]). Assuming that OWL 2 DL will support  
subproperty statements between annotation properties, this change  
should at least partially solve the issue.

Section: Lexical Labels
Language: OWL 2 Full
Issue: objects as values of data property (example)
Suggestion: don't do this

We assume you refer to example 17; we propose to remove this example.

Section: Documentation
Language: OWL 2 Full
Issue: using literal in object property (examples)
Suggestion: don't do this

Section: Documentation
Language: OWL 2 Full
Issue: use of rdf:value (example)
Suggestion: don't use rdf:value

As discussed above, the resolution to ISSUE 135 [3] resulted in the  
SKOS labelling properties being typed as OWL Annotation properties.  
We propose that the documentation properties be treated similarly.  
This would then address the issue of the use of a literal with a  
documentation property. Although this is not then strictly OWL DL  
compliant, we understand that this will potentially fit with OWL 2  

We propose to remove example 25 (the use of rdf:value).

Section: Lexical Labels
Language: not OWL
Issue: axiom schema for unique prefLabel
Suggestion: include qualified cardinality restrictions only
   for languages used (defined using datatype restrictions)

Section: Concept Collections
Language: OWL 2 Full
Issue: ordering with typing
Suggestion: see [1]

Section: SKOS XL
Language: OWL 2 Full
Issue: data property chains
Suggestion: ??

We assume these three issues refer to constraints S14 (lexical  
labels), S35 (ordered collections) and S56, S57 & S58 (SKOS XL).  
Indeed, these constraints can (currently) not be expressed in OWL.  
However, these are useful constraints for tool developers and we  
therefore prefer to keep these in the SKOS Reference.

Please let us know whether you can live with this response.

Thanks again for your comments.

Sean Bechhofer
Alistair Miles
Guus Schreiber

[1] http://lists.w3.org/Archives/Public/public-swd-wg/2008Oct/0059.html
[2] http://www.w3.org/2006/07/SWD/track/issues/157
[3] http://www.w3.org/2006/07/SWD/track/issues/135

Sean Bechhofer
School of Computer Science
University of Manchester
Received on Wednesday, 10 December 2008 19:03:25 UTC

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