- From: Graham Klyne <Graham.Klyne@Baltimore.com>
- Date: Fri, 15 Jun 2001 17:15:13 +0100
- To: Dan Connolly <connolly@w3.org>
- Cc: rdf core <w3c-rdfcore-wg@w3.org>
At 09:20 AM 6/15/01 -0500, Dan Connolly wrote: > > The fact that something can have a URI (and anything can, right?) doesn't > > mean that it's got one. > >Suppose I say that it does. There's no argument to >refute me, is there? i.e. there's no reason not >to adopt this as an axiom. Let's call this something X. At this stage, I discern 3 possibilities: (a) X has no URI (b) X has a URI, but I don't know what it is (c) X has a URI and I know what it is For performing a computation (in our case, interpreting a relative URI), I see no practical distinction between (a) and (b). So, yes, I can adopt this as an axiom, but the inference rules I use to decide possible computations may need to be adjusted as a result. (Previously, I had assumed that if X had a URI I could find out what it was.) > > From a practical viewpoint, having a URI but not knowing what it is > > doesn't seem to be significantly different from not having a URI. > >But this isn't an issue of practical viewpoints; it's >an argument of architectural constraints -- or rather, >lack of them. So the difference is significant. > >You trust that I have a birthday even though you don't >know it, right? By the same token, it seems easy >enough to accept that resources have URIs even though >those URIs aren't always specified. I generally regard "architecture" as a means to achieve a practical end. > > Because (by my lights) a CC/PP profile may be some data that doesn't have a > > URI. > >We disagree on that. OK, so we probably need to frame this discussion in terms that we agree about. [...] > > >Just think of everything as "on the Web". > > > > I don't. That sounds to me more like a religion, or act of faith, than a > > state of affairs. > >Well, that's how architecture and mathematics work, no? Not entirely, I think. One adopts a viewpoint that yields a desired result. >i.e. by the same token, nothing compells you to agree that >2+2=4, nor that the DNS has a unique root. >But it follows from generally accepted axioms, >so you do agree, right? I dispute "nothing compels": life in the modern world would get pretty tough for me if I rejected the notion that 2+2=4. And accepting a unique DNS root helps me access Internet services. > > > It's a matter > > >of perspective. There aren't any constraints in the > > >design of the Web that allow you to deduce a contradiction > > >from saying "every document is on the Web". > > > > More important, I think, than the lack of a contradiction is a sense of > > common understanding (which, also, is an act of faith...). > >Alas, it's true that a lot of folks think of the Web >as HTTP+HTML. I think it's quite reasonable to think of the Web as being more than just HTTP+HTML, without necessarily accepting that it's omnipresent. It's pretty easy to accept the web as a whole range of things that happen on the Internet; for me, it's something of a stretch to also include the weekly groceries or the plants in my garden. Sure, you can do this, but I think that when a concept is allowed too much free reign it loses its potency. I'd say it's useful to develop the idea that the Web can relate to non-Web things, rather than say that everything is "in the Web" without distinction. [...] >I agree that this common understanding is somewhat lacking >and important to achieve; I plan to spend considerable >effort developing it over the next few years. Be careful what you wish for... >But meanwhile, the 10 year history of the Web >is evidence that this axiom is useful; can we agree that >for the purposes of the RDF spec, every document is in the Web? I'll accept that every document, every collection of data, *can* be assigned a URI, which I think is sufficient for the purposes of the current discussion. In my response to Danbri on this topic I said: [[[ Maybe we might say that a relative URI is meaningful only if there *is* a URI (per 5.1.1-5.1.4) relative to which it can be evaluated? ]]] This phrasing could be tightened up somewhat. You might also want to say something about how to interpret a relative URI in RDF if there is no known base URI. #g ------------------------------------------------------------ Graham Klyne Baltimore Technologies Strategic Research Content Security Group <Graham.Klyne@Baltimore.com> <http://www.mimesweeper.com> <http://www.baltimore.com> ------------------------------------------------------------
Received on Friday, 15 June 2001 12:36:16 UTC