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

Re: less-restrictive range and domain terms

From: David Menendez <zednenem@psualum.com>
Date: Tue, 04 May 2004 16:58:48 -0400
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: pdawes@users.sourceforge.net, b.fallenstein@gmx.de, www-rdf-interest@w3.org
Message-id: <r02000200-1033-D74EBCF09E0D11D8AC0B000393758032@[10.0.1.2]>

Peter F. Patel-Schneider writes:

> From: "Phil Dawes" <pdawes@users.sourceforge.net>
> > 
> > Benja Fallenstein writes:
> >  > 
> >  > Peter F. Patel-Schneider wrote:

         Phil Dawes:
> >  > |>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'.

> >  > | Second, what do you mean by 'property *may* have range of
> >  > | class foo'?
> >  > 
> >  > "There exist triples with property P and an object of class
> >  > foo," rather than "All triples with property P have objects of
> >  > class foo," is a useful interpretation, I presume.
> > 
> > Yep - that's what I meant. Sorry for not being clear.
> 
> But suppose that there just doesn't happen to be such a relationship
> in the current world.  What happens then?
> 
> This is not such a problem for property ranges (but does cause
> problems even here), but what about an OWL construct like 
>      the class foo may have range bar for property p
> Does this mean that foo has to be non-empty?

I would say, either foo is non-empty or the "may have range" statement
is incorrect.

However, for the purposes of UI support, which (I think) was Phil's
original goal, there's no need to make any implications at the RDF
level.

For example,

    p:owner s:usualRange p:HumanAgent .
    p:Gorilla owl:disjointWith p:HumanAgent .

If someone was entering RDF data and said:

    _:fido p:owner [ a p:Gorilla ].

this could raise a warning, rather than an error. "Fido's owner is a
gorilla, but owners are usually humans or groups of humans. Are you
sure?"

It's not *wrong*, just *unusual*.
-- 
David Menendez <zednenem@psualum.com> <http://www.eyrie.org/~zednenem/>
Received on Tuesday, 4 May 2004 16:59:44 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:52:07 GMT