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Re: RDFCore Update

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 31 Aug 2001 12:23:12 -0700
Message-Id: <v04210106b7b5933f7d79@[130.107.66.237]>
To: Stefan Kokkelink <skokkeli@mathematik.uni-osnabrueck.de>
Cc: www-rdf-logic@w3.org
>pat hayes wrote:
> > ...
> > >Why did you decide to define it for RDF graphs?
> >
> > ...
> > RDF graphs and Ntriple documents are in 1:1 correspondence, modulo
> > re-ordering of lines and renamings of anonymous node labels, so it is
> > relatively trivial to map between them in any case; and it is also
> > easy to map directly between graphs and (existential-conjunction)
> > expressions in a linear logical notation, should you wish to do so.
> > In fact, if one is willing to put up with the awkwardness of somehow
> > distinguishing between 'free' and 'bound' anonymous nodes, the model
> > theory could be applied directly to the n-triples syntax.
>
>Although I completely agree on this (and on the decisions
>made by RDFCore regarding anonymous nodes and RDF graphs )
>it should be noted that there is no 1:1 correspondence between
>XML serializations and RDF graphs (and hence Ntriple also).

But it is onto, ie every XML serialization maps to a unique graph, 
right? (If not, please give an example.) So if the semantics assigns 
a meaning to every graph, then it also does to every XML 
serialization, which is all that it needs to do in order to provide a 
semantics for  the serialization language.

>I think there are two possible views on this.
>
>1. Accept that not all RDF graphs have a XML serialization.

That would be my own preference. Is there a problem with this?

>2. Define an RDF graph to be a 'valid' RDF graph if there
>   exist a XML serialization.

Well, I'd prefer a different word, call it 'XML-compliant' or some 
such. But this is a different issue, to do with the acceptability of 
RDF graphs to some processor. The model theory only has to provide an 
unambiguous interpretation for every expression; if it also provides 
one for some other expressions that is harmless.

Pat Hayes

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Received on Friday, 31 August 2001 15:22:03 GMT

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