W3C home > Mailing lists > Public > public-owl-dev@w3.org > January to March 2007

RE: declaredAs

From: Boris Motik <bmotik@cs.man.ac.uk>
Date: Fri, 26 Jan 2007 15:57:13 -0000
To: "'Evren Sirin'" <evren@clarkparsia.com>
Cc: "'Matthew Horridge'" <matthew.horridge@cs.man.ac.uk>, <public-owl-dev@w3.org>
Message-ID: <000101c74162$a5abf920$27c35882@wolf>

Hello,

Well, (2) is needed because an obvious property: if we create an ontology,
save it, and then load it back, we would like to get exactly the same
ontology. Otherwise, I'd say that a syntax is obviously broken: it should
completely preserve the set of axioms (logical or nonlogical) that are
contained in the ontology.

There is a big difference between (2) and (3): (3) is used to detect the
type of P, whereas (2) is used to detect whether P has been explicitly
declared. Note that (2) implies (3), but not the other way around: if P is
not declared, you should not serialize its declaredness status, but you
should serialize <P, rdf:type, owl:ObjectProperty>. Hence, there indeed is a
need to distinguish the two if you are to completely recover the state of
the original ontology upon loading.

Sincerely yours,

	Boris

> -----Original Message-----
> From: Evren Sirin [mailto:evren@clarkparsia.com]
> Sent: 26 January 2007 15:22
> To: Boris Motik
> Cc: 'Matthew Horridge'; public-owl-dev@w3.org
> Subject: Re: declaredAs
> 
> On 1/26/07 6:27 AM, Boris Motik wrote:
> > Hello,
> >
> > Well, we've been thinking about this, but decided not to do so for an
> > important reason. Consider an ontology O containing an object property P
> for
> > which there is no declaration. A serialization of O into an RDF graph
> must
> > ensure the following two things:
> >
> > (1) When you parse the graph, you must be able to decode the type of P.
> > (2) The parsing should correctly restore the "declaredness" status of P
> --
> > that is, after parsing, the ontology should not contain a declaration
> for P.
> >
> > Now the problem is that, to ensure compatibility with OWL DL, we use
> > rdf:type to ensure (1). In the worst case, you really need to include a
> > triple
> >
> > (3) <P, rdf:type, owl:ObjectProperty>
> >
> > so that, when you parse the graph, you know what the type of P is. But
> then,
> > you should not use rdf:type to reflect the "declaredness" status of P in
> an
> > ontology; otherwise, any ontology that contains the triple (3) will also
> > contain a declaration for P.
> >
> Boris, could you explain a little why (2) is needed in the first place.
> What kind of problems arise if the ontology after parsing contains a
> declaration for P? If the type of P will be decoded as ObjectProperty in
> the end, having (3) seems harmless.
> 
> Thanks,
> Evren
> 
> > We weren't able to find a way out of this problem and have,
> consequently,
> > introduced the owl:declaredAs property.
> >
> > Thanks anyway for this suggestion!
> >
> > Sincerely yours,
> >
> > 	Boris
> >
> >
> >> -----Original Message-----
> >> From: public-owl-dev-request@w3.org [mailto:public-owl-dev-
> request@w3.org]
> >> On Behalf Of Matthew Horridge
> >> Sent: 26 January 2007 10:06
> >> To: public-owl-dev@w3.org
> >> Subject: declaredAs
> >>
> >>
> >> All,
> >>
> >> I've been working on an OWL 1.1 parser/renderer recently, and I
> >> wondered if we could just use rdf:type instead of owl:declaredAs for
> >> entity declarations in the RDF mapping.  I can't immediately see a
> >> problem with doing this, and I believe it would improve backwards
> >> compatibility with the existing "OWL 1.0" RDF/XML mapping.  Any
> >> thoughts?
> >>
> >> Cheers,
> >>
> >> Matthew
> >>
> >
> >
> >
> >
> >
> >
Received on Friday, 26 January 2007 15:57:41 GMT

This archive was generated by hypermail 2.3.1 : Wednesday, 27 March 2013 09:32:54 GMT