- From: Uche Ogbuji <uche.ogbuji@fourthought.com>
- Date: Tue, 19 Nov 2002 07:51:05 -0700
- To: "Danny Ayers" <danny666@virgilio.it>
- Cc: "RDF-Interest" <www-rdf-interest@w3.org>, xml-dev@lists.xml.org
[Wow. The to/cc headers on this thread seem to be growing without upper bound. Trimmed a bit for now] Shelley Powers: > >> Anyone know of an [RDF] vocabulary using reification? Moi-meme: > >I'm glad they're hard to find. If I saw an RDF vocab using > >reification, I'd > >steer very clear of it. I have a very firm policy of avoiding reification > >like the plague. > >I either use explicit blank nodes or (if I can relax interop > >requirements), > >4RDF statement context/scope annotations. Danny Ayers: > Now that's exactly the thing - apart from being of a nice toy for the > theoreticians, reification should give us context/scope capability without > having to relax any requirements. I've still not got far enough through the > latest spec suite to see how any recent changes might have impacted on the > potential for contexts, but some of the n3 stuff and Graham Klyne's work on > contexts [1] and scoping [2] suggest that it should be possible with little > (or no?) extension to the current specs. > > As I'm sure is the case in practice with 4RDF, contexts aren't particularly > complicated in principle. They should be simple to do within the shared > model. Very simple. Reification shouldn't be the 'big ugly' (as Shelley > nicely put it) to be avoided by sensible developers, it should be a big > friend. I agree that proper context/scopes would be little work to add to core RDF, so I have always wondered: why the complete avoidance of the issue in the specs? This is a matter that almost every RDF implementor has had to rediscover and/or reinvent. I would think a "standard" in development should take note of this fact. As for reification in RDF 1.0, it is B.A.D., to use Tim Bray's cheeky term. It's B.A.D. from a model-theoretic point of view -- the lack of enforceable relationship between the four statements generated by its reification and the original statement itself makes it useless for a lot of the cases at which it is aimed. It's B.A.D. from the implementation POV -- each reification bloats the data store, or the implementation has to add a big-O-rder of magnitude to typical query algorithmic complexity, unless one performs very dodgy tricks with statement hashes and the like (dodgy because of the model-theoretic failings of reification). Thanks for the links, though, I'll reference them from my Akara page on 4Suite RDF scopes. -- Uche Ogbuji Fourthought, Inc. http://uche.ogbuji.net http://4Suite.org http://fourthought.com Python&XML column: 2. Introducing PyXML - http://www.xml.com/pub/a/2002/09/25/p y.html The Past, Present and Future of Web Services 1 - http://www.webservices.org/ind ex.php/article/articleview/663/1/24/ The Past, Present and Future of Web Services 2 - 'http://www.webservices.org/in dex.php/article/articleview/679/1/24/ Serenity through markup - http://adtmag.com/article.asp?id=6807 Tip: Using generators for XML processing - http://www-106.ibm.com/developerwork s/xml/library/x-tipgenr.html
Received on Tuesday, 19 November 2002 09:48:47 UTC