Re: Range interpretation question.

On Wed, 25 Apr 2001, Arjohn Kampman wrote:

> > Which interpretation of range constraints do you prefer?
> > 
> > [ P, rdfs:range, C] 
> >     is intended to express:
> > (a) P may be applied to any resource that belongs to class C
> > or
> > (b) If P is applied to a resource r, r will belong to C
> 
> I'd prefer (a), because using (b) can lead you into strange
> situations:
> 
> Assume that the C is rdfs:Literal and that you're using a resource
> uri as a target of the property. Using (b) this would mean that the
> uri is a literal. To the best of my knowledge, a uri cannot be both
> a resource and a literal.

No, the DAML+OIL axiomatic semantics states that literals are resources.
From Axiom 17:

Ax17.    (=> (Type ?r ?c) (and (Type ?r Resource) (Type ?c rdfs:Class)))

one can conclude (by setting ?c to rdfs:Literal) that

(=> (Type ?r rdfs:Literal) (Type ?r Resource))

Ken Baclawski
UBOT Project
College of Computer Science
Northeastern University