W3C home > Mailing lists > Public > www-rdf-logic@w3.org > August 2001

RE: Summary of the QName to URI Mapping Problem

From: <Patrick.Stickler@nokia.com>
Date: Thu, 30 Aug 2001 12:13:59 +0300
Message-ID: <2BF0AD29BC31FE46B78877321144043114BFBB@trebe003.NOE.Nokia.com>
To: phayes@ai.uwf.edu
Cc: www-rdf-logic@w3.org
> ...
> >
> >Now, we have here two functional layers: RDF, and HTTP. A SW agent
> >may interact with that URI at either level, and the semantics at
> >one level does not have significance at the other.
> Ah, I see what you mean, and agree with you. I thought (too hastily - 
> is there a smilie for eating humble pie?) you were saying something 
> larger and more, er, philosophical about the nature of meaning.

I'm sure I'm greatly to blame for using imprecise terms, not being
sufficiently well versed in KR or logic terminology.

> DAML+OIL, the next 'layer' above RDF for some folk, actually does 
> make some nontrivial use of the HTTP semantics, in a sense, in that 
> it has ways of using URIs to refer to other sets of axioms and import 
> them. This is admittedly a rather simple kind of cross-layering 
> interaction, but it hints at the kind of issues that are going to 
> arise.

But is this really an interaction of the semantics of the RDF graph
and the semantics of the URI? I.e., aren't such mechanisms really just
instructions to the parser? Do those "include" instructions actually
have explicit representation in the graph? And if so, then does not
DAML then define not only an extension of RDF semantics but also 
define a processing model providing methods of knowledge syndication?
And is then the semantics of that processing model part of the semantics
of the graph model? (sorry for so many questions at once)

I still don't see how these layers interact in a way that the semantics
at one level is "semantics" of the same sort or resolution at another 

> >I.e. No URI Scheme can introduce any semantics into RDF. The 
> use of any
> >URI Scheme for resource URIs has no relevance whatsoever to semantics
> >associated with an RDF graph. Right?
> Right, other than ensuring the coherence of the assumption of global 
> name uniqueness (which I think is a *syntactic* matter for RDF.)

Agreed. And in fact this whole mapping problem has been seen from the
start as a syntactic matter (so why is it on the rdf-logic list? good
question ;-)

> All this arose from your central technical point about Qnames and 
> URIs, however, and maybe it would be more useful to get back to that. 
> I now see your point about the use of a URI scheme, but that still 
> seems to me to be basically a matter of politics. Calling a 
> notational convention a URI scheme, as opposed to part of (say) the 
> RDF spec, doesn't change the fact that it *is* a notational 
> convention, and that to ensure its proper use requires that a 
> community of users agree to conform to it. 

This was one of my chief arguments in response to various comments
such as "sounds great, use it if you want to" in relation to any of
the proposed solutions to these mapping issues. I.e. it's not enough 
just to be *able* to use some mechanism that works, the solution has 
to be stipulated in some fashion as a (or rather the) standard way 
to do it. And yes, that part has always been seen as political.

I.e., adoption of a particular solution is political, but the existence
of a problem and the need for a solution is not itself political.

Thanks for your efforts in clarifying the above matters.



Patrick Stickler                      Phone:  +358 3 356 0209
Senior Research Scientist             Mobile: +358 50 483 9453
Software Technology Laboratory        Fax:    +358 7180 35409
Nokia Research Center                 Video:  +358 3 356 0209 / 4227
Visiokatu 1, 33720 Tampere, Finland   Email:  patrick.stickler@nokia.com
Received on Thursday, 30 August 2001 05:14:16 UTC

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