W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > July 2001

Re: A use case for anon nodes - action from telecon

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 26 Jul 2001 14:22:05 -0700
Message-Id: <v0421010eb78638f4af86@[130.107.66.237]>
To: Graham Klyne <Graham.Klyne@Baltimore.com>
Cc: w3c-rdfcore-wg@w3.org
>At 12:25 PM 7/26/01 -0700, pat hayes wrote:
>>>I think that's one of the great unresolved issues of URIs in 
>>>general.  I think either way is sustainable and results in the 
>>>same models, but different folks seem to think differently.
>>
>>Maybe. I think a global unique-name model is sustainable only in a 
>>very fragile sense: if everyone cooperates and nobody ever makes a 
>>mistake or gets confused, then it will work. But one error, 
>>anywhere, could make the entire edifice crumble, since nobody could 
>>then rely on the global assumption being valid.  In fact, I will 
>>undertake to be the fly in the ointment, and will offer a universal 
>>unique-name-wrecking service by generating copies of RDF webpages 
>>with just the names changed.
>
>Well, some folks' thinking as I understand it would have it that you 
>have, by definition, created a distinct set of resources that happen 
>to deliver the same set of entities in response to the same queries.
>
>This is sort-of what I meant by saying they result in the "same 
>model" (which is probably not exactly right), in the sense that the 
>resource itself is a nearly invisible intermediary between a request 
>that names or references the resource (by means of its URI) and a 
>thing one gets back in response to the request.

?? Again, that seems to be a completely different notion of 
'resource' than the one I have been trying to work with. Brian 
assures me, for example, that unicorns are resources, but I never 
expect to get sent one in response to a request.

> RFC2396 talks of resources as "conceptual mapping"s.

Right. It says, in fact:
-------
          The resource is the conceptual mapping to an entity or set of
          entities, not necessarily the entity which corresponds to that
          mapping at any particular instance in time.  Thus, a resource
          can remain constant even when its content---the entities to
          which it currently corresponds---changes over time, provided
          that the conceptual mapping is not changed in the process.
------
which reads to me to be simply incoherent, since if the entity to 
which it corresponds changes, then presumably the mapping to that 
entity also changes (or else it no longer 'corresponds' in any sense 
I can imagine), so whether the resource is the entity or the mapping 
is irrelevant to the issue of whether it retains its identity through 
time.  It may be, of course, that a 'conceptual mapping' isnt 
actually a *mapping*, rather in the way that an imaginary horse isnt 
actually a horse.

>This is all very woolly,

I would use a harsher word, myself.

Pat

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Received on Thursday, 26 July 2001 17:21:56 EDT

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