W3C home > Mailing lists > Public > semantic-web@w3.org > March 2006

Re: Interpretation of RDF reification

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Fri, 24 Mar 2006 11:50:55 +0000
Message-ID: <4423DD1F.2040803@hplb.hpl.hp.com>
To: Dan Brickley <danbri@danbri.org>
CC: semantic-web@w3.org

Dan Brickley wrote:

> It's also worth keeping an eye on the W3C Rule Interchange Format 
> Working Group, see http://www.w3.org/2005/rules/ ->
> http://www.w3.org/2005/rules/wg.html
> They have a use cases and requirements draft out (which I've only
> just noticed by accident, but which appears to be dated today!),
> http://www.w3.org/2005/rules/wg/ucr/draft-20060323.html
> A rule language could be rich enough to handle quoting more robustly
> than RDF reification. But I wouldn't bet on it :) I'd be interested to 
> hear from WG members on this point.

I seem to recall that some of the original submitted usecases for RIF 
mentioned reification[*] but more in the sense of making things like policy 
rules first class objects in the domain, rather than in the sense of RDF 
provenance tracking. I personally wouldn't expect RIF to be the right place 
to re-examine RDF reification.

The charter does include mention of scoped inference (such as scoped 
negation as failure). So it's possible that might mean a rule could ask 
whether some fact was stated in a given scope (e.g. at a particular web 
data source) - but we already have that capability with SPARQL, as you 
pointed out.

Note that the RIF charter does not actually call for a semantic web rule 
language but for a framework for interchange of rules between different 
systems.  I guess someone could make an argument that CWM has a quoting 
mechanism with its nested formulae and request that RIF should be capable 
of interchanging CWM rules with other potentially-compatible-rule-languages :-)

[BTW I don't think it's quite fair to describe RDF reification as not 
"robust" - it does just what it says on the packet. The message from Pat 
that Frank pointed to makes the issues clear and I'm not sure there is a 
better solution. If you want de dicto then you can always use 
literals/XMLLiterals or reference back to the raw document (as your SPARQL 
solution is doing).

For a framework for describing chains of deductions, which seems to be what 
your example is really asking for, then you might find Inference Web 
useful: http://iw.stanford.edu/
That includes an (OWL) ontology for exchanging proof chains.


[*] It amuses me that the Mozilla spell checker suggests "deification" as a 
correction for "reification".
Received on Friday, 24 March 2006 12:13:46 UTC

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