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RE: Grammar question

From: Geoff Chappell <geoff@sover.net>
Date: Sun, 13 Mar 2005 14:48:39 -0500
To: "'Seaborne, Andy'" <andy.seaborne@hp.com>
Cc: <public-rdf-dawg-comments@w3.org>
Message-ID: <005901c52805$a7ebc080$6401a8c0@gsclaptop>

> -----Original Message-----
> From: Seaborne, Andy [mailto:andy.seaborne@hp.com]
> Sent: Sunday, March 13, 2005 1:31 PM
> To: Geoff Chappell
> Cc: public-rdf-dawg-comments@w3.org
> Subject: Re: Grammar question
> One irregularity I plan to keep (unless someone persuades me otherwise) is
> that property slots are not general - they must be URIs or variables.  No
> blank nodes, literals or TriplesNode expansions.  I don't see RDF getting
> literal arcs or arcs-with-triples.  Blanks arcs would very occasionally be
> useful but it's not RDF in spirit.

I've found uses for blank arcs in a couple of cases:

1. RDF-izing XML - one way to do this is to look at elements as resources
with a blank arc between them (that represents the unknown relationship
implicit in the containment). For example:
	xml: <a><b/></a>
 	rdf: [a :a] [] [a :b]

2. Treatment of (naturally) higher arity predicates. For example:

	English: Geoff throws the ball to fido.
	Rdf: ex:Geoff [ rdfs:subPropertyOf ex:throws; ex:to ex:Fido] [a

Whether or not that's a popular modeling metaphor (e.g. I think it's modeled
as a process in sumo rather than anything like this), it still seems like a
reasonable option and potentially worth supporting (and hopefully the
serialization formats will come around :-) ). 

- Geoff
Received on Sunday, 13 March 2005 19:52:28 UTC

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