Re: RDF Semantics: corrections

From: pat hayes <phayes@ihmc.us>
Subject: Re: RDF Semantics: corrections
Date: Tue, 13 Jan 2004 15:36:29 -0600

[...]


> >The comment about being able to
> >prove a new lemma for RDF with the change indicates that there will be some
> >substantive effect to the change.
> 
> We do not plan to actually state this lemma in the spec, note.
> 
> The substantive change is that, as noted above, the class extension 
> of a datatype name is required to contain only the denotations of 
> typed literals in the vocabulary, rather than required to *be* the 
> value space of the datatype. This brings D-interpretations in line 
> with the way that XML typed literals are treated in the RDF 
> semantics, which imposes no explicit requirements on 
> ICEXT(I(rdf:XMLLiteral))

> The only example I am aware of which makes the change visible is this:
> 
> ex:a ex:p "true"^^xsd:boolean .
> ex:a ex:p "false"^^xsd:boolean .
> ex:c rdf:type xsd:boolean .
> 
>   |=?=
> 
> ex:a ex:p ex:c .
> 
> With the current semantics, this is valid (there are only two items 
> in the class extension xsd:boolean,  and so ex:c must denote one of 
> them); with the proposed change, it is not valid (since the class 
> extension of xsd:boolean might consistently contain other items in 
> some interpretations.) In general, the changed semantics requires 
> that typed literals be classified appropriately, but it does not 
> require that class names denote class extensions 'exactly', since any 
> such requirement will break simple Herbrand completeness.

[...]

What about 

ex:p rdfs:range xsd:string .
ex:a ex:p "2"^^xsd:int . 

It appears to me that this is satisfiable under the proposed change, as
opposed to the current situation.

Peter F. Patel-Schneider
Bell Labs Research

Received on Tuesday, 13 January 2004 20:57:12 UTC