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Re: error?

From: Frank Manola <fmanola@mitre.org>
Date: Wed, 03 Jul 2002 15:49:41 -0400
Message-ID: <3D235555.7090200@mitre.org>
To: Garret Wilson <garret@globalmentor.com>
CC: Franco Salvetti <franco.salvetti@tiscalinet.it>, www-rdf-comments@w3.org, Brian McBride <bwm@hplb.hpl.hp.com>, boley@informatik.uni-kl.de

Garret--

There is no real inconsistency here.  The RDF Schema specs say that the 
effects of declaring things like range depend on what applications 
choose to do with those declarations (the original RDF Schema spec and 
the new one are consistent in saying this).  Certainly lots of people 
are going to use processors that interpret schema declarations as 
constraints on instances, and I didn't say they couldn't;  just that 
that was not the only way they could be interpreted.  Note also that in 
this particular case, it works out the same way with either 
interpretation:  if you don't specify a range, there is no constraint, 
and so even if a processor is one that interprets range statements as 
constraints on instance data, there is no constraint to enforce.

--Frank


Garret Wilson wrote:

> Brian,
> 
> ----- Original Message -----
> From: "Brian McBride" <bwm@hplb.hpl.hp.com>
> To: "Franco Salvetti" <franco.salvetti@tiscalinet.it>;
> <www-rdf-comments@w3.org>
> Cc: <boley@informatik.uni-kl.de>
> Sent: Wednesday, July 03, 2002 10:12 AM
> Subject: Re: error?
> 
> 
> 
>>One can think of a range statement as a contraint.  With no range
>>
> statement
> 
>>there is no contraint on the range of rdf:object which is what we want.
>>
> 
> Arrgh. I thought I just spent a huge thread and determined that RDF Schema
> does *not* specify constraints.
> 
> From Frank Manola, 11 June 2002:
> 
> 
>> You're
>> interpreting the RDF Schema as necessarily defining *redundant*
>> information that you can check for consistency against the instances
>> (e.g. that if dc:creator has a range of Person, the resource that's the
>> value of a dc:creator must have a rdf:type property with value Person),
>> but technically the Schema can be equally interpreted as being
>> additional descriptive information about instances (so if you find a
>> resource that's the value of a dc:creator, you can assume it's of type
>> Person because the schema says it must be).
>>
> 
> From Patrick Hayes, 11 June 2002:
> 
> 
>>You SAID that the
>>range of the property was foo:Person, and then you SAID that the
>>value of the property on something was a bag. It follows inexorably,
>>from the usual meaning of 'range', that you have said that the bag is
>>a foo:Person. If you didn't mean that, why did you say it?
>>
> 
> Arrgghh... :)
> 
> Garret
> 
> 
> 


-- 
Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
Received on Wednesday, 3 July 2002 15:37:05 GMT

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