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Re: [LC response] To Ivan Herman- LC comment on OWL 2 QL

From: Ivan Herman <ivan@w3.org>
Date: Thu, 26 Mar 2009 07:03:59 +0100
Message-ID: <49CB1ACF.9020703@w3.org>
To: Uli Sattler <sattler@cs.man.ac.uk>
CC: public-owl-comments@w3.org
Thanks a lot Uli. I am satisfied with the answer.


Uli Sattler wrote:
> Dear Ivan,
> Thank you for your comment
>      <http://lists.w3.org/Archives/Public/public-owl-wg/2009Feb/0007.html>
> on the OWL 2 Web Ontology Language last call drafts.
> Your comment is closely related to the one by Maurizio (see 
> http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0014.html) and 
> Misha (see 
> http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0019.html).
> The working group has decided to implement the editorial changes and 
> will correct the typos, thanks for pointing them out. We have also 
> decided to add, to OWL 2 QL, reflexive, irreflexive, & asymmetric 
> property axioms.
> Finally, we have decided *not* to add sameAs or functional properties to 
> OWL 2 QL:
> - [sameAs] OWL 2 QL was designed so that any query Q against an ontology 
> whose data (i.e., information about individuals, the classes they are 
> instances of and how they are related via properties) is stored in a 
> relational database DB, can be answered by rewriting the query Q into an 
> SQL query Q1 and then answering Q1 against DB using a standard RDBMs. 
> This property is known to be lost in the presence of sameAs. For the LOD 
> community, we have added a small paragraph explaining that, if one wants 
> to handle ontologies that are OWL 2 QL plus sameAs, then one can use a 
> preprocessing step that materializes the sameAs relation and uses it in 
> query answering procedures to simulate individual equality reasoning 
> (see http://www.w3.org/2007/OWL/wiki/Profiles#Feature_Overview_2).
> - functional properties can only be added under the so-called unique 
> name assumption, i.e., different names denote different indiviudals. 
> This assumption, together with functional properties, will lead to 
> inconsistencies if an individual has 2 successors w.r.t. a functional 
> property -- a semantics that is suitable for some applications and 
> unsuitable for others. Hence we have chosen to not include functional 
> properties to OWL 2QL.
> Please acknowledge receipt of this email to 
> <mailto:public-owl-comments@w3.org> (replying to this email should 
> suffice). In your acknowledgment please let us know whether or not you 
> are satisfied with the working group's response to your comment.
> Regards,
> Uli Sattler
> on behalf of the W3C OWL Working Group


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Thursday, 26 March 2009 06:05:17 UTC

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