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Re: Importing SKOS model in ontology editors : problem with OWL full

From: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
Date: Fri, 3 Apr 2009 15:11:14 +0100
To: public-swd-wg@w3.org
Message-ID: <20090403141114.GB25372@skiathos>
Hi all,

Because various people have been asking for and using an OWL 1 DL
prune of the SKOS ontology (e.g. Simon Jupp in SkosEd, Johannes Busse
below), I think we need to address this point.

Sean has published an OWL 1 DL prune of SKOS at [1], which seems
sensible to me, based on what sean said he did to generate it [2], tho
i haven't looked at it in detail. Personally, I'm happy for this
resource not to have any official W3C status, but think we should at
least make some statement about it, and do something to raise its
profile, make it more discoverable.

I leave to the chairs' discretion as to when best to raise as an
agenda item.



[1] http://www.w3.org/2006/07/SWD/SKOS/reference/20090315/skos-dl.rdf
[2] http://lists.w3.org/Archives/Public/public-esw-thes/2009Mar/0024.html

On Wed, Mar 25, 2009 at 03:12:27PM +0100, Johannes Busse wrote:
> Hi Sean,
> I understand your point, and I was aware that there where some  
> discussions. I'm personally very fond of SKOS, and I'm trying to show  
> our partners it's benefits. Because of that I'm very disappointed with  
> the results w.r.t. this OWL full issue.
> We now have the situation that we have (a) a normal language  
> recommendation and (b) an OWL1 full ontology, (c) intentionally no  
> formal version which is tractable, e.g. OWL1 DLP , OWL2 EL, OWL2 RL or  
> sth. similar.
> Because an OWL1 full ontology is incomplete and not sound, from a semweb  
> practicioner point of view this situation means that we simply have  
> *nothing* at hand which can be used in professional semantic systems --  
> at least in systems which have to strive at soundness and completeness  
> of their models.  SKOS 2008 doesn't fit practical needs; for the time  
> being it's purely academic.
> Alistair Miles wrote:
> > Just to let you know that last week the SKOS Reference Candidate
> > Recommendation was published, ...
> > The working group will shortly be sending out an official calling for
> > implementations, so watch this space.
> With this OWL1 full issue it is *not possible* to provide a sound and
> complete implementation. Are the editors aware of that?
> It's also part of my job to write project proposals. Until now I have  
> written "... We also strive at integrating SKOS terminologies into XYZ".  
> If the SKOS editors insist not to define sth. like an OWL1 DL (or  
> alternatively an OWL2) version, in the next proposal I'd have to write  
> sth. like
>     "Because inferencing with SKOS 2008 is not sound neither complete,  
> we'll define a tractable subset of SKOS -- called 'skos lite' -- in  
> order to allow for integrating terminologies similar to SKOS into XYZ."
> Nobody want's to have such a situation.  What could be done?
> yours,
> Johannes
> Sean Bechhofer wrote:
>> Bernard, Johannes
>> The OWL Full/DL issue was discussed in the WG (see, e.g. ISSUE-38 [1]). 
>> During the LC period, the WG took a decision to change the typing of  
>> labelling and documentation properties to be Annotation Properties (see 
>> also discussion concerning resolution of ISSUE-157 [2]). Although the  
>> presence of subproperty assertions between the labels and rdf:label and 
>> and the documentation properties and skos:note violate the DL  
>> constraints, it was our understanding that OWL 2 would move towards  
>> supporting subproperty relationships between annotation properties.  
>> Adopting this design will hopefully minimise potential changes in the  
>> future in order to provide an OWL2-DL conformant vocabulary 
>> (personally, I also believe that defining those properties as 
>> annotation properties is also more appropriate).
>>> Here you point to such a prune candidate:
>>> > http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos-dl.rdf
>> I have regenerated the "DLised version" of the SKOS vocabulary [3]. The 
>> version is produced by removing some of the axioms that violate the DL  
>> constraints, in particular, those axioms relating to the subproperty  
>> assertions concerning labelling and documentation properties. This is a 
>> similar approach to that you discussed for the geonames. Note that this 
>> does *not* form part of the SKOS recommendation, but may be of some use 
>> in tools (it was originally done to support some tooling being 
>> developed by Simon Jupp [4]).
>>> I have fed this to
>>> - http://www.mygrid.org.uk/OWL/Validator
>>> which gives back OWL DL plus some minor errors ("Possibly using wrong 
>>> vocabulary (rdf:Property instead of owl:[Object|Data]Property)...")
>> These aren't errors, but are rather warnings. They are generated 
>> because the SKOS vocabulary contains (redundant) assertions about 
>> properties. For example, there are triples that state:
>> skos:inScheme rdf:type owl:ObjectProperty.
>> skos:inScheme rdf:type rdf:Property.
>> These redundant triples were included to support non OWL aware  
>> applications [5].
>>> Then we have a first question:
>>> - Would the editors of SKOS agree that this (or a similar) OWL DL  
>>> subset   reflects most of their *intended* semantic?
>> Speaking personally, yes (and I would hope so as I generated it :-). As 
>> discussed above, it is missing the subproperty assertions (and other  
>> statements concerned with metadata -- dc/dct vocabulary), but in so far 
>> as it is possible to produce a SKOS OWL DL vocabulary, I believe it to  
>> be a good fit.
>> Cheers,
>>     Sean
>> [1] http://www.w3.org/2006/07/SWD/track/issues/38
>> [2] http://www.w3.org/2006/07/SWD/track/issues/157
>> [3] http://www.w3.org/2006/07/SWD/SKOS/reference/20090315/skos-dl.rdf
>> [4] http://code.google.com/p/skoseditor/
>> [5] http://www.w3.org/2008/11/18-swd-minutes.html
>> -- 
>> Sean Bechhofer
>> School of Computer Science
>> University of Manchester
>> sean.bechhofer@manchester.ac.uk
>> http://www.cs.manchester.ac.uk/people/bechhofer
> -- 
> Dr. Johannes Busse, Senior Researcher
> An der RaumFabrik 29, D-76227 Karlsruhe
> Reg. Office: Karlsruhe, Amtsger. Mannheim, HRB 109540
> Managing Directors:    Prof.Dr.J.Angele,  H.P.Schnurr
> http://www.ontoprise.de   | phone x49(721) 509 809-62
> mailto:busse@ontoprise.de | mobile x49(163) 509 80-62

Alistair Miles
Senior Computing Officer
Image Bioinformatics Research Group
Department of Zoology
The Tinbergen Building
University of Oxford
South Parks Road
United Kingdom
Web: http://purl.org/net/aliman
Email: alistair.miles@zoo.ox.ac.uk
Tel: +44 (0)1865 281993
Received on Friday, 3 April 2009 14:11:50 UTC

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