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Re: Advancing translational research with the Semantic Web

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Thu, 17 May 2007 15:40:01 +0100
Message-Id: <B77E1921-411C-4BAC-BA63-0F2F24055E34@cs.man.ac.uk>
Cc: public-semweb-lifesci <public-semweb-lifesci@w3.org>
To: Chris Mungall <cjm@fruitfly.org>

On 17 May 2007, at 05:13, Chris Mungall wrote:
[snip]
> I've never understood why RDF-reification is so loathed. So the  
> syntax is ugly - but I think there may be other reasons RDF/XML  
> hasn't won any beauty contests.

They are fairly ugly at the model level as well. And there are  
problems with nesting, see:
	http://cs-www.cs.yale.edu/homes/ddj/papers/ISWC02.pdf

RDF reification was sort of intended to handle both syntactic and  
semantic extension (i.e., quoting), but never specified which and  
didn't really consider lots of situations. (For example, it's not a  
syntactic error to be missing a predicate triple in a  
reification....what does this mean? Some systems, I believe, treat  
the presence of a reified triple as implying the asserted triple, but  
not everyone. RDF/XML has special syntax for asserted+reifiction, but  
not reification alone.)

> The lack of semantics seem fine to me (although more could be done  
> to clear up some misunderstandings in the documentation) - all I  
> want is a way to attach provenance to a statement.

This lack of semantics is the main issue, IMHO.

> The only support I'd want would be some behind-the-scenes  
> optimising away of the fact I have 4n triples when a single 3-ary  
> predicate would do (but hey, again, as it's RDF anyway, I need at  
> least 4 triples for each type-level statement).

Jena, to my recent surprise, does this. You can even get some syntax  
joy by using an id on the property element so long as you are ok with  
the triple *also* being asserted.

> Though support in other syntaxes like SPARQL would be nice, and  
> presumably easy to layer on, perhaps in some intermediate  
> representation.

I think it would be a good and wise thing at this juncture to step  
back and consider viable alternatives that are well designed for one'  
problem space. I think it's still possible to make a switch, but  
every project that falls back on reification because it's "standard"  
enshrines it a bit more.

Cheers,
Bijan.
Received on Thursday, 17 May 2007 14:39:13 UTC

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