W3C home > Mailing lists > Public > www-rdf-interest@w3.org > May 2004

Re: less-restrictive range and domain terms

From: Benja Fallenstein <b.fallenstein@gmx.de>
Date: Tue, 04 May 2004 19:09:33 +0200
Message-ID: <4097CE4D.5050909@gmx.de>
To: Jon Hanna <jon@hackcraft.net>
Cc: "www-rdf-interest@w3.org" <www-rdf-interest@w3.org>

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Jon Hanna wrote:
| Quoting Phil Dawes <pdawes@users.sourceforge.net>:
|>I've recently found myself wanting a less-restrictive version of
|>rdfs:range (or owl:allValuesFrom) and rdfs:domain. I want to say
|>'property *can* have range of class foo' rather than 'property *must*
|>have range of class foo'.
|
| The property then has a range which is a superclass of class foo.

Hm, Resource is a range for every property, and also a superclass of
every class, so this doesn't seem very useful. :)

I understand what you mean: intuitively, "the" right range of pet:owner
might be foaf:Person. There are larger ranges -- AnimateObject -- and
more specific ranges -- PetOwner, PersonOwningSomething -- but you'd
normally think of "the" range as foaf:Person.

Then, any subclass of foaf:Person would, intuitively, qualify for "can
have range." For example, "pet:owner canHaveRange Parent", because
parents are potential pet owners, but definitely not "pet:owner
canHaveRange rdfs:Property", because RDF properties cannot own pets,
that makes no sense.

Perhaps 'P canHaveRange C' should be read as, intuitively "It is
conceivable that there are resources of class C that are objects of
triples with property P."

This is broader than my earlier proposal of "There *are* resources of
class C that are objects of triples with property P." Still, it can be
inferred from "X P Y, Y rdf:type C." It is fuzzier, but captures Phil's
intent better, I guess.

- - Benja
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Received on Tuesday, 4 May 2004 13:10:36 GMT

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