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Re: restrictions bnodes

From: Graham Klyne <gk@ninebynine.org>
Date: Fri, 09 May 2003 19:50:00 +0100
Message-Id: <>
To: Brian McBride <bwm@hplb.hpl.hp.com>, jan grant <Jan.Grant@bristol.ac.uk>
Cc: RDF Core <w3c-rdfcore-wg@w3.org>

At 11:24 09/05/2003 +0100, Brian McBride wrote:
>Jan, Graham,
>A couple of questions:
>a) Were you aware of the restrictions on bnodes (individuals can't be 
>objects of > 1 triple, and no cycles of individuals) from your review of AS+S?
>b) Do you consider such restrictions significant?

[post-telecon] This may be too late...

I noticed it, but I'm not clear about the exact role of OWL so I'm not sure.

I think the matter of working with things described by "in-the-wild" RDF is 
crucial here:

- if the scope of OWL-DL/lite restrictions is to the actual OWL 
descriptions that are used to describe things, then it seems OK.

- if, on the other hand, the restrictions apply to any RDF about the things 
thus described, I think there's a problem.

For example, I tend to think of OWL as a bit like "RDFS on steroids", and, 
like RDFS, I imagine that one can create OWL descriptions of things which 
can be used as the basis for certain kinds of reasoning.  This doesn't 
prevent us from saying all sorts of other things about the same resources 
using "untamed" RDF.  I think this is OK, modulo one concern:  given some 
mixed RDF in a single graph, we want to be able to separate the OWL parts 
from the non-owl parts, the latter remaining opaque to OWL reasoners.  (I 
say I think it's OK, I mean as far as RDF is concerned -- having lots of 
common RDF data opaque to OWL may not be good for OWL, but that's another 

If, on the other hand, one is prevented from using *any* untamed RDF to 
describe anything about which one wants to reason using OWL, then I think 
there's potentially a serious architectural disconnect.


Graham Klyne
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E
Received on Friday, 9 May 2003 15:10:53 UTC

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