- From: Chris Dollin <kers@hplb.hpl.hp.com>
- Date: Thu, 23 Mar 2006 16:24:18 +0000
- To: semantic-web@w3.org
On Thursday 23 March 2006 15:44, Peter F. Patel-Schneider wrote:
> Not really. OWL in RDF gives you much more than specialized relations.
> Much of the power of OWL comes from syntax that is more than just single
> relations. It so happens that it is possible to embed OWL in RDF in a
> certain manner. (This is not always possible, by the way, and OWL is very
> close to the maximum expressiveness that can be so embedded in RDF.)
Could you articulate which bits of OWL semantics are /more/ than the
semantics given by the meanings of the OWL predicates and classes?
> > So if you take the relation owl:inverseOf then this is just an [RDF]
> > relation.
>
> Well, sure, owl:inverseOf is *just* an RDF property, in RDF. In OWL, on
> the other hand, owl:inverseOf is a special property - it has a extra
> meaning provided by the OWL semantics.
>
> > But it is linked to the following well known rule:
> >
> > { ?r1 owl:inverseOf ?r2 .
> > ?a ?r1 ?b . } => { ?b ?r2 ?a . } .
>
> Not all all. There are *no* rules in RDF, nor in OWL. The above is not
> even legal RDF syntax, nor legal OWL syntax.
The OWL defining document isn't written on OWL, but that doesn't stop
it defining the OWL semantics.
When I introduce an predicate into my RDF -- say, kers:birthDate -- I
can explain what that predicate /means/ to people who want to use it.
I can't state that meaning in RDF, I can't state it in OWL, I can't teach
the machine what it means - but it's useful because it has that meaning,
and I can say that the statement `kers:Chris kers:birthDate 1-Jan-2006`
is false. The /RDF/ semantics doesn't do that, but it doesn't stop me
doing it.
--
Chris "x.f(y) == f(x, y) == (x, y).f" Dollin
The shortcuts are all full of people using them.
Received on Thursday, 23 March 2006 16:24:37 UTC