- From: Dan Brickley <danbri@danbri.org>
- Date: Sat, 16 Jan 2010 10:23:51 +0100
- To: Peter Ansell <ansell.peter@gmail.com>
- Cc: Pat Hayes <phayes@ihmc.us>, Danny Ayers <danny.ayers@gmail.com>, jeremy@topquadrant.com, tai@g5n.co.uk, "semantic-web@w3.org" <semantic-web@w3.org>
On Sat, Jan 16, 2010 at 9:52 AM, Peter Ansell <ansell.peter@gmail.com> wrote: > Sorry, I hadn't read through the definition for blank node properly. > If I had realised that Blank Nodes could actually represent anything, > instead of my naive, incorrect, view that they were just placeholders > for URI's. I do understand why Blank Nodes can't be put in the > predicate position currently though. They're placeholders in the sense that a URI is missing from the graph at that point. But since URIs can (webarch tells us) name anything too, your understanding might not have been too far off. (aside) RDF bNodes are a form of 'missing information'; in general, RDF makes it possible to exchange information where you've got bits of it missing, since we try to assemble a fuller picture by pulling together fragments of the whole story from diverse sources. "Missing isn't broken"(*), but sometimes it is nevertheless really really annoying. Throwing a generated URI into the graph instead of leaving it nameless (blank) makes it easier for others to attach properties at that point in a subsequently super-imposed graph, although sometimes this comes with unwelcome syntactic, privacy or other processing burden. I'm no more pro-bNode than I am pro-ignorance, but it's often useful to be able to mention things and focus on identifying them via their well known properties, rather than their unknown URIs. cheers, Dan (*) http://web.archive.org/web/20031003223643/http://rdfweb.org/mt/foaflog/archives/000047.html
Received on Saturday, 16 January 2010 09:24:25 UTC