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Re: rdfs:Property rdfs:range questions

From: Jeen Broekstra <jeen.broekstra@aidministrator.nl>
Date: Fri, 20 Sep 2002 13:13:21 +0200
Message-ID: <3D8B02D1.2070104@aidministrator.nl>
To: m batsis <mbatsis@netsmart.gr>
CC: www-rdf-interest@w3.org

m batsis wrote:

 > * Can someone please point to what a property range defaults to?

It does not default to anything. If the range is unspecified, then
that's it: no range. Same for domain.

 > * IF I am correct, when a property has multiple ranges, all of them
 > must be satisfied (does not make sence to me;-). Can someone please
 > explain the reasons behind this?

There is an interesting discussion about this in the mailinglist
archives (actually, there are several :)), that may shed some light on
this. One possibly interesting thread starts at
http://lists.w3.org/Archives/Public/www-rdf-interest/2000Sep/0132.html

The issue can also be found the in the RDF issue list that the RDF Core
WG maintains:

http://www.w3.org/2000/03/rdf-tracking/#rdfs-domain-and-range

 > * How can I have two dissjoint ranges in the same property?

You can't.

Or actually you can, but then no instances can exist that use this property.

By the way, most[1] inferencers over RDF Schema interpret the
domain/range property semantics as inference rules rather than
constraints, which basically means that whenever you introduce a
property p with a certain range R (p rdfs:range R), and you introduce a
instance a with that property (a p b), its value is automatically
derived to be of type R (b rdf:type R).

Regards,

Jeen

[1] for sufficiently low values of most, that is :)
-- 
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Received on Friday, 20 September 2002 07:14:17 GMT

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