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RE: comment on the fragment document: (inverse) functional and DL-Lite

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Thu, 6 Mar 2008 11:56:41 -0000
To: "'Ivan Herman'" <ivan@w3.org>
Cc: <public-owl-wg@w3.org>
Message-ID: <005201c87f81$24775c10$7212a8c0@wolf>

Hello Ivan,

Please let me explain the way in which the fragments have been defined. In the introduction, we said that, for each fragment, we
show the productions that are different from the complete OWL 1.1 language. We did this in order to avoid duplication of the
material.

Please note that the complete OWL 1.1 language contains the following production. Effectively, <objectPropertyAxiom> is responsible
for OWL 1.1 allowing for (inverse)functional object properties.

objectPropertyAxiom :=
    subObjectPropertyOf | equivalentObjectProperties |
    disjointObjectProperties | inverseObjectProperties |
    objectPropertyDomain | objectPropertyRange |
    functionalObjectProperty | inverseFunctionalObjectProperty |
    reflexiveObjectProperty | irreflexiveObjectProperty |
    symetricObjectProperty | asymetricObjectProperty |
    transitiveObjectProperty



In the DL-lite section, however, we redefined this production to the following one:

objectPropertyAxiom :=
    subObjectPropertyOf | equivalentObjectProperties |
    disjointObjectProperties | inverseObjectProperties |
    objectPropertyDomain | objectPropertyRange |
    symetricObjectProperty

Effectively, this disallows the (inverse)functional object properties in DL-lite. In other words, starting from the <ontology>
nonterminal, there is now no way to get into the <functionalObjectProperty> nonterminal; hence, these are not allowed. The
production <functionalObjectProperty> can thus be seen as "dangling".



We used this approach throughout the document: whenever some production is not redefined, we do not repeat it. Admittedly, while
this makes the definition of each fragment more concise, it makes it also rather difficult to see what exactly is and what isn't
supported by the fragment. But for this purpose, we presented an overview of the supported features before giving the grammar
productions. We listed the supported and the not supported features.


Now you are right in that we forgot to list the (inverse)functional object properties in the list of the missing features of
DL-lite. Thanks for that; I've updated the document. If you find further omissions, please let us know and I'll add them to the
appropriate section.

Regards,

	Boris

> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Ivan Herman
> Sent: 06 March 2008 11:04
> To: boris.motik@comlab.ox.ac.uk; bcg@cs.man.ac.uk
> Cc: public-owl-wg@w3.org
> Subject: comment on the fragment document: (inverse) functional and DL-Lite
> 
> Boris, Bernardo,
> 
> I went through
> 
> http://www.w3.org/2007/OWL/wiki/Fragments_Proposal
> 
> again today. One thing that I may have missed: I tried to see if I can
> use (inverse)functional properties for DL-Lite or not. I did not find
> any reference to those neither in 3.1 nor in 3.2. Again, I may have
> missed something...
> 
> I also have some more editorial comments, but I will send them in a
> separate mail
> 
> Ivan
> 
> --
> 
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Thursday, 6 March 2008 11:57:45 GMT

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