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Re: Properties no longer required to be resources?

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: 31 Jul 2003 11:48:24 +0100
To: pat hayes <phayes@ihmc.us>
Cc: rdf core <w3c-rdfcore-wg@w3.org>
Message-Id: <1059648504.3160.13.camel@dhcp-91-3.hpl.hp.com>

Hi Pat,

Sorry if you get this twice - having email trouble again.

On Wed, 2003-07-30 at 20:18, pat hayes wrote:
> >I just noticed an editorial (?) tweak (pointed out by pfps) to the
> >semantics document that the semantic constraint that properties must be
> >a subset of resources has been removed from the current editors draft.
> >
> >http://www.w3.org/2001/sw/RDFCore/TR/WD-rdf-mt-20030117/#interp
> >
> >Pat, this is rather more than just an editorial tweak.
> 
> This is only for simple interpretations. It does not make any 
> difference to RDF or RDFS interpretations, since those 
> interpretations are still required to conform to the subset condition 
> by virtue of their semantic conditions; cf. section 3, 5th para 
> (after the table of RDF semantic conditions):

I am greatly relieved to hear that.  I didn't read the para you quote. 
I just checked the maths of the semantic conditions and they didn't seem
to require that properties are resources.  I then checked the (now
complete?) closure rules in 7.2 and couldn't see how the desired
entailment could be attained from them either.

I know better than to argue mathematics with you, but maybe you could
point out what I'm missing?

[...]

> The only document in the entire RDF document suite which mentions 
> simple entailment is the semantics doc, and all the lemmas in section 
> 2 still hold.
> 
> >Test case:
> >
> >   sss ppp ooo .
> >
> >rdf entail
> >
> >   ppp rdf:type rdf:Resource .
> >
> >I believe the answer should be yes, but in any case the answer is
> >distinguishable in RDF.
> 
> The answer is yes.  No RDF entailments are affected by this change.

Could someone please spell it out for me, cos I can't see the
derivation.

> 
> If you really feel that this is a serious matter then I can go back 
> and undo this, but I would rather not,

I don't want any changes either, at this stage.  I'd much prefer to be
assured that I'm wrong.  In RDF, properties are resources, and if the
semantics ain't saying that, I do think that's a problem.

Brian
Received on Thursday, 31 July 2003 06:49:20 EDT

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