- From: Richard Newman <r.newman@reading.ac.uk>
- Date: Sat, 29 Jul 2006 22:19:27 -0700
- To: "Xiaoshu Wang" <wangxiao@musc.edu>
- Cc: =?ISO-8859-1?Q? "'Reto_Bachmann-Gm=FCr'" ?= <reto@gmuer.ch>, "'Semantic Web'" <semantic-web@w3.org>
I will step in here to correct a couple of things. On 29 Jul 2006, at 8:52 PM, Xiaoshu Wang wrote: >> Sorry, that's nonsense. Not only property URI's are not >> necessarily dereferenceable and the possibly available graph >> representation may or may not contain that statement - do you >> know about any FOAF client behaving as you're suggesting it >> should? I don't, and I know I wouldn't want to install it on >> my mobile phone of limited resources. > > Are you sure you are talking RDF? The only thing that is not > dereferencable > is literal values because they are not URI. But literal can only > be an > object, not subject and property. Not true. Only a subset of URIs are dereferenceable, and even fewer are dereferenceable to yield RDF. The following are a few examples: - tel:, mailto: etc. URIs - tag URIs, which are explicitly not dereferenceable - probably the majority of used HTTP URIs, because they are essentially 404s by default, or yield non-RDF data. Furthermore, not all properties are of the form <dereferenceable RDF URL> + #propertyName I often use slashes instead of hashes, and what you get from a web server serving up a representation of that URI is probably not a fragment of the ontology. > I don't know too much about FOAF. But I do know FOAF does not > deploy its > ontology at its namespace (is that why you said a property is not > necessarily dereferenable?) and I think this practice is a very bad > practice. Because it assumes agent to have preexisting knowledge > to work > with something, it sort of make the open-world somewhat closed. > IMHO, it is > bad and very bad. Last I checked, http://xmlns.com/foaf/0.1/ returns HTML or RDF according to your HTTP request, which might be amusing given the topic under discussion. -R
Received on Sunday, 30 July 2006 05:19:39 UTC