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Re: RDF graph model limited by RDF/xml 1.0 syntax?

From: Dan Connolly <connolly@w3.org>
Date: Thu, 27 Sep 2001 18:05:30 -0500
Message-ID: <3BB3B0BA.DB642770@w3.org>
To: Pat Hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org
Pat Hayes wrote:
> 
> >Consider this nice, clean graph model for RDF
> >(borrowing liberally from Peter F. Patel-Schneider's
> >message to www-rdf-logic of Thu, 27 Sep 2001 10:37:29 -0400):
> >
> >An RDF graph is a four-tuple (that can be considered to be a
> >partially labeled, directed graph; the unlabelled nodes
> >are bNodes)
> >                 < N, E, LN, LE >
> >         where N is the set of nodes in the graph
> >               LN :(partial) N -> URI u L gives labels for nodes
> >               LE :(partial) E -> URI gives labels for edges
> >               E <= N x N is the set of edges in the graph
> 
> Why is LE partial? Is that deliberate?

It was deliberate, yes. It evidently wasn't sufficiently
careful, though.

[...]
> >(not in the issues list?)
> >   can I use a bNode in the predicate part of an RDF statement?
> >
> >       yes.
> >
> 
> In N-triples, yes. But its not like the node case in the graph; here,
> that bNode label has to really be in the graph; and then it had
> better be there for 'unlabelled' nodes as well, since otherwise there
> is  no way to know that a bNode used as an arc label is the same as a
> bNode labelling a node. Basically, the whole 'tidyness' notion goes
> out the window when we have bArcs., and much of the simplicity of the
> graph syntax is lost.
> 
> Still, we could live with N-triples as a canonical syntax, if we want
> to go that way.

Hmm... I see. I'll have to think about that.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 27 September 2001 19:05:31 EDT

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