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

From: Aaron Swartz <me@aaronsw.com>
Date: Wed, 18 Jul 2001 17:52:43 -0500
Message-Id: <200107190312.f6J3C1j02147@theinfo.org>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: rdf core <w3c-rdfcore-wg@w3.org>
On Tuesday, July 17, 2001, at 04:30  AM, Brian McBride wrote:

> The thing to bear in mind about this submission is that these
> were not my words.  They were the words (with some HP specific
> stuff removed) of my colleagues who are using RDF in the manner
> described.  This input is from real developers.

I understand that, sorry if it seemed I was asking questions 
directly of you, but instead I meant to use you as a gateway to 
understand more background about the example.

>>> (1) In the seller advert it would appear that the seller is
>>> only advertising a single specific (but under-specified) 
>>> service, #anon12345 or
>>> whatever, which would be hard to distinguish from an actual 
>>> service instance
>>> like #service42.
>> Why would you want to distinguish between the two?
> I think the idea here is that there will be URI's
> denoting specific services.  My colleagues are
> interpretting a node with a URI to be denoting
> such a service.  It would be wrong to match a different
> service.
> When an anonymous node is specified, then no such constraint
> exists.  Thus a processor would process these two instances
> differently.

I'd suggest that it might be better to model this in a way that 
made this more clear, such as:

<#anon12345> a :QueryForService .

or some such. In other words, I feel that they are depending on 
unspecified semantics of anonymous resources, which explicit 
statements would make much clearer.

>> And I see nothing about a URI that licenses you to assume that 
>> there is
>> only such thing.
> Oh we really do need this model theory don't we.  I tend to think
> of a URI as identifying one thing, and one thing only, but that way
> lies a philosphical debate on the nature of 'one'.  Shudder!

Heh, it identifies one "conceptual mapping" perhaps, but that 
can map to other things. Otherwise lists wouldn't make much 
sense, now would they?

> The essence of this issue seems to involve the idea that the
> act of naming something in the internet is somehow, special.
> That if a processor is told that something has URI ISBN-12345
> or whatever, it had better not match that with anything that
> it does not 'know' is named ISBN-12345.  On the other hand,
> if a node is not named, then it can be matched with anything
> that matches its properties.

Pat Hayes has said repeatedly that one can pretty much only 
infer from an existential the same things they could from a 
specific identifier. Obviously, he has studied this more than I 
have, but it seems to me that people are asking anonymous nodes 
to mean more than they really do.

Clearly, whatever way we decide, it's important to clarify this,
--
       "Aaron Swartz"      |           Blogspace
  <mailto:me@aaronsw.com>  |  <http://blogspace.com/about/>
<http://www.aaronsw.com/> |     weaving the two-way web
Received on Wednesday, 18 July 2001 23:10:00 EDT

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