- From: Brian McBride <bwm@hplb.hpl.hp.com>
- Date: Tue, 24 Jul 2001 11:26:32 +0100
- To: pat hayes <phayes@ai.uwf.edu>
- CC: w3c-rdfcore-wg@w3.org
pat hayes wrote: > > > > o scope: An application given a resource identified by a URI > > can reasonably expect to pass that URI to other applications and > > that they should be able to recognise it - c.f. my example > > on seeking references about a service offered in response to an ad. > > I think this is wrong on several grounds. First, there is not in > general any way to 'identify' the resource denoted by a URI. If I am > given a URI then I may or may not be able to discover what resource > it was intended to identify, but there is no general presumption that > this can always be done. Yes I agree that it can't always be done. With an anonymous resource it can never be done. With a URI it can sometimes be done. That is a difference and it may be significant to an application. > Second, while of course the other > application can recognise the URI in the sense that they know where > it comes from, there is no general presumption that they can > 'identify' what it denotes, ie discover exactly what resource that > was supposed to be. In many cases this may be possible (eg it will be > for URL's presumably), but not in general. They may have some information about it, e.g. reference service. > > > If the response includes a reference to a service identified by > > a URI, the receiver could reasonably pass that URI to reference > > service to seek a credit/quality reference for that service. > > There is no point doing that for a variable. > > > > o binding: An application given a resource identified by a URI > > can assume that URI denotes a specific resource - the > > binding decision has been made - an existentially quantified > > variable has not been bound to a specific resource. > > I disagree. What do you mean by 'binding' here? I mean that the mapping from the URI to the resource it identifies has been defined. > There doesnt seem to > be any reasonable sense of binding for a URI. see above. > Certainly there isnt > any way to bind a URI to the resource it denotes, in general (cf > http://lists.w3.org/Archives/Public/www-archive/2001Jun/att-0021/00-pa > rt#33 > "A resource may also be an object that is not directly accessible via > the Web; e.g. a printed book. ..... Anything can have a URI; the > extensibility of URIs allows the introduction of identifiers for any > entity imaginable." We seem to have different notions of binding. > > > o provenance: when a source of rdf states some properties about > > a resource named by a URI it is making assertions that the > > resource named by that URI has those properties. when a source > > of rdf states properties about a variable, it is making no > > assertions about the name of that resource. > > In both cases, it is making assertions about some thing, ie some > resource. The use of the URI may enable the receiver to connect the > assertions made by the source to other assertions (perhaps made by > other sources) about the same thing, made by using the same URI. That > is the only sense in which a URI can be said to 'name' anything. > > It isnt clear to me what the scope of anonymous node is intended to > be, but it if it is the document containing the node, then indeed it > should be impossible for any other source to say anything about the > thing it refers to, so this is a genuine difference. However, the > same is true of a non-anonymous URI if its use is restricted to this > one source. If I can tell that the scope of such a URI is so limited, then I think I might be happy with that - so long as I can tell such URI's from those those are not so limited. Brian
Received on Tuesday, 24 July 2001 06:29:07 UTC