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Re: forest grammar/tree regular expression for RDF (fwd)

From: Dan Brickley <Daniel.Brickley@bristol.ac.uk>
Date: Mon, 25 Jun 2001 11:40:52 +0100 (BST)
To: Dan Connolly <connolly@w3.org>
cc: Jonathan Borden <jborden@mediaone.net>, w3c-rdfcore-wg@w3.org
Message-ID: <Pine.GSO.4.21.0106251129300.16939-100000@mail.ilrt.bris.ac.uk>
On Sun, 24 Jun 2001, Dan Connolly wrote:

(on Jonathan Borden's RELAXNG work...)

(msg trimmed to focus on rdf:Description question)

> > I have specified this as a RELAXNG schema for RDF
> > http://www.openhealth.org/RDF/RDF1.rng in terms of solidifying the RDF XML
> > syntax under the issue:
> > http://www.w3.org/2000/03/rdf-tracking/#rdfms-formal-grammar
> 
> Very nice!
> 
> It has a few special cases that I don't think are necessary
> (e.g. rdf:value is just another propertyElement/propertyAttribute,
> and rdf:Description is just a typedNode) but other than
> that, it seems to be quite a compact and precise description of
> the RDF syntax.
> 

[...]

> Production 4 is ambiguous, no?
> 
> 4.type description = 
>              rdf:Description[
>                      idAboutAttr?,
>                      bagIdAttr?,
>                      propAttr?,
>                      propertyElt*
>              ] |
>              typedNode
> 
> <rdf:Description/> matches both alternatives, no?
> 
> As I say, I don't see any need to special-case
> rdf:Description in the grammar.


If we take this reading of the syntax, then the presence of
rdf:Description asserts an rdf:type relationship between the described
resource and an rdfs:Class called rdf:Description.

I've seen nothing in RDF elsewhere to support the claim that RDF defines
such a class; M+S is pretty clear that the rdf:Description construct is
pure encoding syntax.

If we were to decide that such a (goofily named) class exists, would it
be something like a subclass of rdfs:Resource?  Your proposal seems to
make the rules for our XML encoding syntax simpler at the cost of making
the resulting structures more complex. 

Dan
Received on Monday, 25 June 2001 06:43:16 EDT

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