W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2002

Re: No more labeled nodes

From: Dan Connolly <connolly@w3.org>
Date: 30 Oct 2002 17:15:16 -0600
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: Brian McBride <bwm@hplb.hpl.hp.com>, w3c-rdfcore-wg@w3.org
Message-Id: <1036019717.7448.170.camel@dirk>

On Wed, 2002-10-30 at 16:37, pat hayes wrote:
[...]
> Then Dave can just delete "identified by".  Nodes *are* urirefs 

yes, please.


Some details:

> --------
> 
> 0.2 Graph syntax
> 
> .....
> To describe RDF graphs it is first necessary to define the things 
> that can act as nodes and arcs of the graph. There are three kinds of 
> node in an RDF graph: urirefs, blank nodes and literals. A uriref is 
> defined to be a URI reference in the sense of [RFC 2396]. Blank 

to be an +absolute+ URI reference in the sense of...

> (unlabeled) nodes are considered to be drawn from some set of 
> 'anonymous' syntactic entities which have no label and are unique to 
> the graph. Two graphs which differ only by having different blank 
> nodes are isomorphic;

I think I know what you mean there, but it doesn't seem
very precise. Hmm...

> we will not bother to distinguish between 
> isomorphic graphs. Literals come in several forms. Simple literals 
> consist of a unicode character string plus an optional XML language 
> tag;

Please, no. Just like urirefs *are* labels, strings *are*
literals, please. That is:

	Simple literas are either unicode character strings
	or unicode character strings paired with a
	language tag.

(language tags aren't novel to XML; they're an Internet-wide
thing.)


> typed literals consist of a unicode character string paired with 
> a uriref which indicates a datatype; and a special class of XML typed 
> literals is distinguished which can also have an XML lang tag. 
> Finally, every arc in an RDF graph is labelled with a uriref. The 
> same uriref may label several arcs and also be a node in the graph. 
> An RDF graph can then be formally defined as a set of triples of the 
> form <S, P, O>, where P is a uriref, S is either a uriref or a blank 
> node, and O is either a uriref, a blank node, or a literal.
[... very nicely put...]



-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 30 October 2002 18:16:00 EST

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