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RE: fragments question re DL-Lite

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Tue, 18 Mar 2008 06:31:40 -0000
To: "'Jim Hendler'" <hendler@cs.rpi.edu>, "'Web Ontology Language \(\(\(\(OWL\)\)\)\) Working Group WG'" <public-owl-wg@w3.org>
Message-ID: <001301c888c1$ba062650$0200a8c0@wolf>

Hello,

In DL-lite, you can have only existential quantification to owl:Thing, and not to other classes in the subclass position in
SubClassOf axioms. Hence, you can write

SubClassOf(ObjectSomeValuesFrom(R owl:Thing) B)

but not

SubClassOf(ObjectSomeValuesFrom(R C) B)


In the superclass position, however, you can have arbitrary classes; hence, the following is fine:

SubClassOf(ObjectSomeValuesFrom(R owl:Thing) ObjectSomeValuesFrom(R C))


The former restriction is necessary in order for the language to be first-order reducible for query answering.

Regards,

	Boris

> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Jim Hendler
> Sent: 18 March 2008 01:17
> To: Web Ontology Language ((((OWL)))) Working Group WG
> Subject: fragments question re DL-Lite
> 
> 
> In the document it reads (Section 3.1)
> 
> > The following constructs can be used to define subclasses in
> > SubClassOf axioms:
> > ...
> >     * existential quantification to a class ( ObjectSomeValuesFrom )
> > where the class is limited to owl:Thing,
> 
> 
> and
> 
> > The following features of OWL 1.1 are missing in DL-Lite:
> >
> >     * existential quantification to a class (ObjectSomeValuesFrom),
> 
> I assume the latter is for class other than owl:Thing?  Do we mean
> here only the class owl:Thing or any class that is a subclass of
> owl:Thing?  If the former, is that just included for completeness or
> is there a real case where it could be useful?
> 
> thanks
>   JH
> 
> 
> 
> "If we knew what we were doing, it wouldn't be called research, would
> it?." - Albert Einstein
> 
> Prof James Hendler				http://www.cs.rpi.edu/~hendler
> Tetherless World Constellation Chair
> Computer Science Dept
> Rensselaer Polytechnic Institute, Troy NY 12180
> 
> 
> 
> 
Received on Tuesday, 18 March 2008 06:33:06 GMT

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