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RE: How to put "universal" restrictions to members of two classes

From: Yoshio FUKUSHIGE <fukushige.yoshio@jp.panasonic.com>
Date: Mon, 06 Sep 2010 15:06:51 +0900
To: public-owl-dev@w3.org
Cc: fukushige.yoshio@jp.panasonic.com
Message-Id: <20100906150512.A286.60B3E2E2@jp.panasonic.com>
Hi Michael,
Sorry for the delay in responding.

> No, it was correct that sub property chain axioms only take object
> properties. It is just that in OWL (2) Full all (RDF) properties happen to
> be object properties. Even "rdf:type", as you use it in the property chain
> axiom of your proposed solution, is an object property in OWL Full. 

This is because thre is no distinction between individuals and classes in OWL Full, right?

> Of course, you can still use the term "rdf:type" in property chain axioms
> directly in the OWL 2 syntax, and the OWL 2 Direct Semantics will even
> interpret it, since the OWL 2 Direct Semantics allows for interpreting the
> whole OWL 2 syntax, not only the particular fraction called "OWL 2 DL" (that
> is, the OWL 2 syntax with the OWL 2 DL constraints being applied; see the
> beginning of Chap. 3 of the OWL 2 Structural Specification). But this will
> still not give you the expected reasoning result, since that "rdf:type"
> property is then only some ordinary object property without any connection
> to class assertion axioms.

Is that because a reasoner doesn't have to be conformant to the RDF Based Semantics
which does define semantics of the term "rdf:type", but can be conformant only
to the Direct Semantics which says nothing about the term "rdf:type"?

> >But does that mean my statements were valid in OWL2 RL??
> If by "valid in OWL 2 RL" you mean that it was a valid OWL 2 RL ontology,
> then the answer is no. The OWL 2 RL (syntactic!) profile is a sub-syntax of
> the OWL 2 DL syntax. Hence, since your input has not been a valid OWL 2 DL
> ontology, it cannot be a valid OWL 2 RL ontology.
> That you can apply the OWL 2 RL/RDF rules does not mean that you are
> restricted to the OWL 2 RL syntax. The OWL 2 RL/RDF rules define a semantics
> (defined by the set of first-order logic axioms the rule set consists of)
> and can formally be applied to arbitrary RDF, even to "generalized" RDF
> (e.g. allowing for literals in subject position).

I see. (thogh a kind of puzzled)

> >From looking at it, Pavel's solution seems to work well in OWL 2 DL. So go
> with this solution if you need to use Pellet or some other OWL 2 DL
> reasoner, or if you want/need to stay in OWL 2 DL. However, I remember that
> you asked whether there can be a specific property between two classes which
> indicates - and allows for inferring - a certain relationship between all
> pairs of instances of these classes. Your own OWL 2 Full solution was pretty
> obvious (from an OWL 2 Full perspective, at least) and really worked. So
> it's now kind of a close-modeling-vs-constraining-technology tradeoff, and
> you have to decide for yourself what has priority for you. In any way, you
> are in the lucky position that there are working solutions for both
> approaches.

I have to consider the scalability to some extent and I, for my shame, don't
know how to use concrete reasoners of OWL 2 Full/RL with my Joseki.
So, I'm going to try with the approach suggested by Pavel, 
trying to give some mnemonics to the 'brige' entities/properties,
to make the developing ontologies easier especially putting N-ary
(all to all) relationships.

Thank you very much for your kind advices.


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Received on Monday, 6 September 2010 06:07:30 UTC

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