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Re: inheritance inside property

From: Jeen Broekstra <jeen@aduna.biz>
Date: Thu, 03 Feb 2005 10:12:02 +0100
Message-ID: <4201EAE2.9030903@aduna.biz>
To: Kianoush Eshaghi <Kianoush.Eshaghi@metadat.at>
Cc: 'RDF interesting groupe' <www-rdf-interest@w3.org>

Kianoush Eshaghi wrote:
> A vocabulary (charily asserted an "ontology")can be modeled by RDFS
> according to object-oriented technique, for example a property can be
> inherited by some super property.
> 
> My question is does my property inherit the all domains and ranges of
> its super property, if I let inherit the property?

No, it does not, save by implication (at least in the normative 
intensional semantics of RDFS - http://www.w3.org/TR/rdf-mt/).

What I mean is this: suppose we have a property p with a domain A :

  p rdf:type rdf:Property.
  p rdfs:domain A.

and we create a subProperty q :

  q rdfs:subPropertyOf p.

RDFS does _not_ entail:

  q rdfs:domain A.

However, whenever we _use_ the property q in a statement, like so:

x q y.

Because q is a subProperty of p we infer (rule rdfs7):

x p y.

...and because the domain of p is A we infer (rule rdfs2):

x rdf:type A.

So "implicitly" the domain is carried over the subproperty.

If you look at the RDF Semantics  section 4.1 and 7.3.1, you will find 
there a specification of extensional entailments. In such a stronger, 
extensional interpretation, the domain restriction _is_ explicitly 
inherited. Most implementations of RDF/RDFS reasoners stick to the 
intensional semantics, however.

HTH.

Jeen
-- 
Jeen Broekstra          Aduna BV
Knowledge Engineer      Julianaplein 14b, 3817 CS Amersfoort
http://aduna.biz        The Netherlands
tel. +31(0)33 46599877  fax. +31(0)33 46599877
Received on Thursday, 3 February 2005 09:11:03 GMT

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