W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > April 2002

Re: Range constraints on collection members

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 5 Apr 2002 18:35:57 -0600
Message-Id: <p05101514b8d3ef2fdce2@[]>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: w3c-rdfcore-wg@w3.org
>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.

Then maybe they should be using DAML ? Look, RDF is a simple 
language. Various people will definitely want more than RDF can 
provide. We cannot insert new features just because they are needed: 
then we really would be doing Web Logic, as Massimo has accused us of 

>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.

We could add this, but its not clear what it would do to the 
semantics. I have an uneasy feeling that it might be quite 
complicated. This is a limited kind of a restriction-on-property (the 
container is restricted to things that have the appropriate range 
property) and that seems to rather go beyond RDFS.

IHMC					(850)434 8903   home
40 South Alcaniz St.			(850)202 4416   office
Pensacola,  FL 32501			(850)202 4440   fax
Received on Friday, 5 April 2002 19:40:00 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 20:24:11 UTC