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Range constraints on collection members

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Fri, 05 Apr 2002 06:31:04 +0300
To: ext Graham Klyne <Graham.Klyne@mimesweeper.com>, RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B8D2F528.128AF%patrick.stickler@nokia.com>
On 2002-04-04 22:51, "ext Graham Klyne" <Graham.Klyne@MIMEsweeper.com>

> At 06:02 PM 4/4/02 +0100, Brian McBride wrote:
>> RDF Schema Issues
>>     * rdfs-constraining-containers: Should it be possible to constrain
>> the members of a container to be of a given type?
> I have a vague recollection we'd decided to defer this one??  (i.e. that
> RDFS 1.0 would provide no such capability.)

I just recieved email from an implementor, Garret Wilson at Global Mentor,
that this is sorely needed for what they are doing.

I encouraged him to post a summary of the issue to RDF comments.

My present take on this is that we need an additional constraint
property that applies to containers, such as rdfs:containerRange
which would be used in conjunction with rdfs:range.

We can't simply extend the semantics of rdfs:range to collections
because one may wish to say that a property must take a collection,
not just a single value, and thus, rdfs:range breaks. What is
needed is an additional constraint mechanism, such as something
like rdfs:collectionRange which would apply to the members of
a collection. One would then specify e.g. that the property's
rdfs:range would be rdf:Bag and the rdfs:collectionRange would
be xsd:string, etc.

If the rdfs:range is xsd:string, then a value of rdf:Bag is in
fact a range violation since an instance of rdf:Bag is not
an instance of xsd:string.



Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Thursday, 4 April 2002 22:28:30 UTC

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