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Re: Comments from RDFCore on S+AS

From: Dan Connolly <connolly@w3.org>
Date: 30 May 2003 12:17:54 -0500
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: public-webont-comments@w3.org
Message-Id: <1054315074.21362.294.camel@dirk.dm93.org>

Thanks for the review; we're working thru these.
Some interim notes...

On Fri, 2003-05-09 at 12:02, Brian McBride wrote:
> The RDFCore WG has me to forward the comments below on their behalf.  Other 
> comments, on behalf of RDFCore will be sent in separate messages.
> Brian
> ------------------------------
> owlsas-rdfcore-np-complete
> RDFCore notes the a consequence of the rules for owl:equivalentClass is
> that distinguishing OWL DL from OWL Full has complexity NP complete and
> suggests WEBONT investigate whether this complexity can be reduced.
> We note from the RDF semantics document
> [[
> Specifications of such syntactically restricted semantic extensions MUST 
> include a specification of their syntactic conditions which are sufficient 
> to enable software to distinguish unambiguously those RDF graphs to which 
> the extended semantic conditions apply.
> ]]
>    http://www.w3.org/TR/rdf-mt/

This is different from the design the WG has agreed to; there
doesn't seem to be any editorial fix that's responsive to this

The WG decided[29May] to fix this problem.
The minutes aren't all that clear about what the fix looks like;
when the spec text that results from the fix is available, we'll
ask you to let us know if it satisfies you.


> -------------------------------
> owlsas-rdfcore-bnodes-restrictions
> RDFCore are concerned that restrictions placed on b-nodes will limit the
> applicability of OWL DL to an unnecessarily restricted subset of RDF
> instance data, for which no such restrictions apply.
> For example, consider the use case in:
>    http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003May/0109.html
> [[
> If bNodes can only be used as the object of a single triple, they lose most
> of their value as a construct in the language. As does rdf:nodeID for that
> matter.
> <Image>
>   <depicts>
>    <Person>
>      <mbox rdf:resource="mailto:danbri@w3.org"/>
>    </Person>
> </Image>
> <Group>
>   <member>
>    <Person>
>     <homepage rdf:resource="http://www.w3.org/People/DanBri/"/>
>    </Person>
>   </member>
> </Group>
> ...is OK in OWL, but if we add in an rdf:nodeID on the two Person elements
> to express that they serialize descriptions of the same (un-named) resource,
> we're in trouble? Ouch. That breaks most of my uses of RDF, and a lot of
> deployed FOAF documents.
> ]]
> Specifically we request, that in Owl DL and Owl lite:
>    a) that a b-node representing an individual may be the object of more
> than one triple
>    b) that cycles of b-nodes representing individuals be allowed.

This is also a substantive design change; we started discussiong
it [29May] but didn't reach a decision.

> -------------------------------
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 30 May 2003 13:17:35 UTC

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