W3C home > Mailing lists > Public > www-rdf-logic@w3.org > September 2001

Re: model theory for RDF/S

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Wed, 26 Sep 2001 14:57:37 -0500
Message-Id: <p0510102cb7d7e10ee939@[]>
To: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Cc: www-rdf-logic@w3.org
>Very interesting! A few comments:
>Section 3, 1:
>"...every member of S also satisfies E'"
>I guess this is E, not E'...


>Section 3.1, 3:
>"A tidy ground instance with respect to any set which is disjoint from
>I may be wrong but this sound redundant: how could possibly be tidy an
>instance with respect to a set including URIs from vocab(E) ?

yes, good point. We changed the notion of 'instance' (it once 
included a tidying) and this form of words is left over from the 
earlier usage. I will rephrase this in the next version.

>Section 3.1, Skolemization Lemma:
>typo: sk() becomes SK().


>Section 5:
>in rules 3b and 4, bbb should be uuu
>(or the produced triples may have a literal as subject or predicate)

The N-triples notation does not allow literals to occur in the 
property position, so these cases would give rise to errors in any 
case; but I agree this could be expressed more clearly.

>I also think that in the example, some triples are missing from the
>given closure (though these are triples which will be generated for
>every schema closure):

That is true, but the text only says that the listed triples will be 
*included* in the closure. The wording could be misleading, so we 
will correct it in the next version.

>   rdfs:Resource rdf:type rdfs:Resource
>   rdfs:Resource rdf:type rdfs:Class
>   rdf:Property rdf:type rdfs:Resource
>   rdf:Property rdf:type rdfs:Class
>   rdfs:Class rdf:type rdfs:Resource
>   rdfs:Class rdf:type rdfs:Class
>I guess that's all... :)

I know what you mean. It is easy to get RDFS-triple-exhaustion.

>By the way, wouldn't that be as easy as generating all those triples to
>automatically include the Schema for RDFSchema, which makes much of them
>explicit directly ?

Perhaps. There were several alternative ways to describe RDFS, and we 
considered several of them. In the end it seemed simpler to simply 
list all the generational rules, even though they do not constitute a 
very 'efficient' representation.

Thanks for the input.

Pat Hayes

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Received on Wednesday, 26 September 2001 15:57:31 UTC

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