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RE: A proposal for ISSUE-104 (built-in vocabulary)

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Wed, 11 Jun 2008 18:50:45 +0100
To: "'Michael Schneider'" <schneid@fzi.de>
Cc: <public-owl-wg@w3.org>
Message-ID: <007f01c8cbeb$acfbdf00$4012a8c0@wolf>

Hello,

But consider the case where you use declare rdf:first as and owl:ObjectProperty, but your ontology also contains a nominal
containing a literal. In the serialization of the ontology, you'll have

_:x rdf:first "c"^^xsd:string

but you'd also have

rdf:first rdf:type owl:ObjectProperty.

But then, you've just showed the constant "c"^^xsd:string into the individual domain. Under OWL DL semantics, your graph is now
unsatisfiable. Under OWL Full semantics, it is really not clear what happens.

Regards,

	Boris

> -----Original Message-----
> From: Michael Schneider [mailto:schneid@fzi.de]
> Sent: 11 June 2008 18:16
> To: Boris Motik
> Cc: public-owl-wg@w3.org
> Subject: RE: A proposal for ISSUE-104 (built-in vocabulary)
> 
> Hi Boris!
> 
> Regarding the 'rdf:first' problem: Your proposal would introduce special
> treatment for the List vocabulary in OWL 2. My own idea, stated in an
> earlier mail, was the opposite: To simply ignore the list vocabulary (except
> in those parts of the reverse mapping where it is applied as part of the
> syntax).
> 
> This would have the effect that rdf:first would be just some URI. And this
> would mean that, in order to use it, one would need to declare it to be
> either an owl:ObjectProperty or an owl:DatatypeProperty, respectively. For
> example, the following would then be legal OWL 2 DL:
> 
>   rdf:List rdf:type owl:Class .
>   rdf:first rdf:type owl:DatatypeProperty .
>   rdf:rest rdf:type owl:ObjectProperty .
>   rdf:nil rdf:type owl:NamedIndividual .
> 
>   :alice :likesNumbers ( 2 3 5 7 ) .
> 
> The declarations could be imported, of course, no need to write them down
> every time.
> 
> It wouldn't be possible to use rdf:first both as an object and a data
> property in the same ontology. But this is what one would expect in OWL 2
> DL.
> 
> Michael
> 
> >-----Original Message-----
> >From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org]
> >On Behalf Of Boris Motik
> >Sent: Wednesday, June 11, 2008 12:33 PM
> >To: public-owl-wg@w3.org
> >Subject: A proposal for ISSUE-104 (built-in vocabulary)
> >
> >
> >Hello,
> >
> >The discussion around ISSUE-104 (reserved vocabulary) seemed to show
> >that lists and reification are the main, if not the only part
> >of the reserved vocabulary that might be useful in OWL 2 DL. (If we feel
> >that it is necessary, we may verify this by sending an
> >e-mail to owl-dev once we have fleshed out our proposal. I personally
> >don't think we need to do this, given my experience how the
> >built-in vocabulary has been used in OWL 1.)
> >
> >Based on the assumption that we more or less agree on the above
> >observation, I would like to put forward a proposal for resolving
> >this issue. Before I do so, let me first explain why the obvious way of
> >resolving the problem does not work.
> >
> >
> >1. A slight problem with exempting rdf:List from the reserved vocabulary
> >------------------------------------------------------------------------
> >
> >For a property to be used in any OWL 2 DL axiom, the property must be
> >declared as either an object or a data property. Now this
> >causes a slight problem for rdf:List: we would make a hard-and-fast
> >choice about how to treat rdf:first. Thus, we would have to
> >decide whether rdf:first is an object or a data property, which would
> >essentially restrict the usage of lists in OWL 2 DL in a nasty
> >way.
> >
> >
> >2. A possible way forward
> >-------------------------
> >
> >To allow for lists, we would introduce four new vocabulary elements in
> >OWL 2:
> >
> >- owl:List
> >- owl:firstLiteral
> >- owl:firstIndividual
> >- owl:rest
> >
> >To ensure semantic compatibility with OWL Full, we would make owl:List a
> >subclass of rdf:List, owl:firstLiteral and
> >owl:firstIndividual a subproperty of rdf:first, and owl:rest a
> >subproperty of rdf:rest.
> >
> >We would extend the structural spec to provide built-in declarations for
> >these properties (in the obvious way). We would also add a
> >subsection to the structural spec and to the primer about how these are
> >to be used in ontologies.
> >
> >We would leave the rest of the built-in vocabulary in OWL 2 DL as it
> >currently is.
> >
> >Note that this does not address the reification vocabulary. Reification
> >is considered bad in RDF anyway, and it would introduce
> >similar problems in OWL 2 DL; therefore, it seems to me that disallowing
> >it in OWL 2 DL is not a big deal.
> >
> >
> >
> >Let me know how you feel about this.
> >
> >Regards,
> >
> >	Boris
> >
Received on Wednesday, 11 June 2008 17:52:19 GMT

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