[Fwd: Re: [OWL] Annotations on subclass axioms etc.]
dvr at aifb.uni-karlsruhe.de
Thu Nov 17 14:21:04 EST 2005
Just to keep you informed on our break-through results :) (I always
forget to type the reply-to-all button, gosh)
-------- Original Message --------
On 11/17/05, Denny Vrandecic <dvr at aifb.uni-karlsruhe.de> wrote:
> >>Well, you could kinda put the axioms x,y and z into the ontology o and
> >>then make statements about o, because o is just another URI as well, and
> >>if I remember correctly the spec doesn't state that ontologies and
> >>instances have to be disjoint.
> > hmm..but the problem still remains: there is no way to say that it is
> > the specific combination of those three axioms alone which achieves
> > some purpose. I mean you could use reification to talk about
> > individual statements in the ontology, but not about some particular
> > statements as a collection unless you use rdf:Bag or Xpointers or
> > something funky like that..(which doesnt have standard OWL-DL
> > semantics)
> > For example, suppose I have three axioms:
> > Jack rdf:type PhdStudent
> > PhDStudent subClassOf someValuesFrom(hasAdvisor, Professor)
> > hasAdvisor subPropertyOf knows
> > I want to add an annotation in my ontology that the above three axioms
> > taken together entail "Jack knows some Professor"...how can one do
> > this easily?
> I think it is pretty easy. You have the following ontologies:
> Jack type PhDStudent
> PhDStuden sco someValuesFrom(hasAdvisor, Professor)
> hasAdvisor spo knows
> Jack type someValuesFrom(knows, Professor)
> and finally we can say in the ontology q:
> o entails p
> It's just, your ontologies get much more finegrained then you're used
> to. And I don't like this too much, but it seems to solve the problem.
hmm..I see what you mean...its interesting
> >>But Sean keeps telling me that there is no real semantic connection
> >>betwen o and (x,y,z), which I am simply not clever enough to grasp.
> > my understanding is that the ontology (o) gives the *context* for
> > those axioms (x,y,z)..i.e., in general an ontology is a set of axioms
> > taken to mean something together (in the context of the ontology) and
> > so I do think there is a semantic connection in that regard.
> > For example, in your ontology, you may have the three axioms "Penguin
> > subClassOf Bird", "Bird subClassOf hasValue(canFly, "true"),
> > "FunctionalProperty(canFly)". But I can take those three exact axioms,
> > add it to my ontology which has a fourth axiom "Penguin subClassOf
> > hasValue(canFly, "false")" and assuming I use the same namespaces, I
> > now have a contradiction and the class "Penguin" is unsatisfiable.
> > Clearly, the context (ontology) has made all the difference for the
> > same 3 axioms.
> Let me paraphrase this, only to see if I understood it right: only
> axioms that belong to the same ontology may be regarded together. If I
> have ontology o with axiom a and ontology p with axiom b, I actually
> would have to create a new ontology q (which may be virtual) that
> imports o and p, thus has the axioms (a,b) and only then I can reason
> about q (and maybe find out its unsatisfiable or whatever).
> Well, OK, if that is the case I am happy, cause this is the way I
> understood it as well.
> Or did I get it wrong?
yep, thats right..after all, when we say reason over an ontology your
reasoning over all axioms together in that ontology..
PhD Candidate, Dept. of Computer Science
GRA, MINDSWAP Research Group,
University of Maryland, College Park
Web page: http://www.mindswap.org/~aditkal
Institute AIFB, University of Karlsruhe (TH)
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