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Re: LANG: syntactic version for imports (and other things)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 25 Sep 2002 07:39:09 -0400 (EDT)
Message-Id: <20020925.073909.68532147.pfps@research.bell-labs.com>
To: Bernard.Horan@Sun.COM
Cc: www-webont-wg@w3.org

From: Bernard Horan <Bernard.Horan@Sun.COM>
Subject: Re: LANG: syntactic version for imports (and other things)
Date: Wed, 25 Sep 2002 11:35:38 +0100

> Sorry to come to this party a little late... but I'm not convinced that
> the decision you came to below works for me...
> 
> "Peter F. Patel-Schneider" wrote:
> > 
> > From: Jim Hendler <hendler@cs.umd.edu>
> > Subject: Re: LANG: syntactic version for imports (and other things)
> > Date: Mon, 16 Sep 2002 22:55:00 -0400
> > 
> > > I now fully understand the difference in understanding between me and
> > > Peter - turns out there is something in the DAML+OIL model theory
> > > that I never realized -- according to separate info that I received
> > > from Peter and others, the following turns out to be legal DAML
> > > (syntactically)
> > >
> > > 1)
> > > URI1 has an ontology called AAA, including class XXX
> > >
> > > 2)
> > > URI2 has an ontology called BBB,
> > > and a class YYY that states it is a subclass of URI1:XXX.
> > >
> > > if I understand correctly, however, I am told that this means that
> > > while YYY makes this claim, since it has no imports statement to AAA,
> > > it as if this subclass statement didn't exist.
> > 
> > I can't imagine how you came up with this idea.  The second ontology
> > certainly has all the effects of the subclass statement.
> > 
> > What is true, at least as far as I can see, is that information about
> > referenced resources is not imported unless there is an imports statement.
> > That is, if document 1 contains a DAML+OIL ontology including
> >    YYY rdfs:subClassOf XXX .
> > and document 2 contains a DAML+OIL ontology including
> >    ZZZ rdfs:subClassOf YYY .
> > but no imports statements, then the ontology in document 2 knows nothing
> > about YYY being a subclass of XXX.
> 
> what's the consequence of this for a reasoner looking at document 2? 
> 
> Let's extend your example and say that document 3 contains a DAML+OIL
> ontology including 
> 	AAA rdfs:subClassOf ZZZ
> 	AAA rdfsLsubClassOf YYY
> 
> without any imports statements. If I wish to point a reasoner at
> document 3 to ensure that (say) it has no inconsistencies (in the same
> way that I can point FaCT at an OilEd document), does this mean that I
> have to indicate somewhere that the ontology in document 3 should
> 'import' the ontology in document 2? 

No.

> Should it also 'import' the
> ontology in document 1? 

No.

> Or should it only 'import' the ontology in
> document 1 if that ontology is not imported by the ontology in document
> 2? 

No.

> I.e. what's the transitive character of 'import' here? 

Importing a document also imports its imports.

> And how do I,
> as a user, know which ontologies I should be importing??

The ontologies that contain information that you need and believe in.

> cheers
> 
> Bernard

peter
Received on Wednesday, 25 September 2002 07:39:18 GMT

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