Re: How does RDF/OWL formalism relate to meanings?

On Apr 11, 2004, at 11:04 PM, John Black wrote:
[snip]
> In the RDF Semantics Recomendation it states:
>
> "1.2 URI references, Resources and Literals.
> This document does not take any position on the way that URI references
> may be composed from other expressions, e.g. from relative URIs or
> QNames; the semantics simply assumes that such lexical issues have been
> resolved in some way that is globally coherent, so that a single URI
> reference can be taken to have the same meaning wherever it occurs."
> - http://www.w3.org/TR/rdf-mt/#urisandlit
>
> What is the effect of the language, "...so that a single URI
> reference can be taken to have the same meaning wherever it occurs."?
> How important is this assumption to RDF semantics?

Upon reflection, that isn't the best wording.

Roughly: In the *graph* there are only absolute URIs. There also are no 
contexts, so every node labeled with the same uri is equivalent.

*Between* graphs, however, URIs can behave quite differently (until you 
merge them).

I'd say it's pretty important :)

Note that URIs in literals (e.g., in literals of datatype xsd:anyURI) 
are exempt from this merging. So the above text isn't quite right if 
you try to read it in full generality.

Cheers,
Bijan Parsia.