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Re: SEM: List's

From: Dan Connolly <connolly@w3.org>
Date: 23 Oct 2002 13:57:52 -0500
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Cc: www-webont-wg@w3.org
Message-Id: <1035399472.10053.7465.camel@dirk>

On Fri, 2002-10-04 at 02:41, Jeremy Carroll wrote:
[...]
> Clearly this is no big deal really - the same work can be done in WebOnt. 

That's not clear to me...

This situation would be unacceptable to me:
  - you can take the URI of rdf:first and dereference it; in
   there, you find a reference to the RDF core spec(s);
   these *don't* specify that rdf:first is functional.
   you find no reference to WebOnt specs.
  meanwhile
  - the webont spec says "rdf:first is a FunctionalProperty".

Whatever the semantics of rdf:first are, you need to be
able to get them by following your nose: deferencing
its address, following links from there to specs, from
those specs to others, and so on. No back-link services
required.

I'm not sure exactly how to resolve the dependency...

Here's an idea:

WebOnt defines a owl:List subclass of rdf:List, on which
rdf:first is functional; also, there's a local
range constraint on rdf:rest so that the rest
of an owl:List is an owl:List. This owl:List
class is the range of properties like owl:intersectionOf.

[...]
> My understanding was that RDF Core agreed to provide the List syntax, and 
> the List vocabulary (rdf:List, rdf:first, rdf:next rdf:nil); but not to 
> provide any (formal) semantics for these terms.

Yes, that's what I remember deciding, and it's a position I support.

Darn it, the rdf:collection stuff was decided 31May
http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002May/0159.html
but that record doesn't show the "there are no interesting
entailments around rdf:first/rest" comment that I thought
I made and I thought we agreed to.


> 
> The rationale included:
> 
> - RDF does not include equality,
> - RDF does not include contradiction,
> - RDF closures of finite graphs are finite
> 
> All three of these appear to be violated by what you are implicitly 
> proposing to include in the next RDF MT WD.
> 
> ---
> 
> Clearly this is no big deal really - the same work can be done in WebOnt. 
> My understanding is that list semantics do belong in WebOnt for the reasons 
> identified above.
> 
> Jeremy
> 
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 23 October 2002 14:58:46 GMT

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