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Re: Terminology Question concerning Web Architecture and Linked Data

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 13 Aug 2007 11:53:41 -0500
Message-Id: <p06230903c2e63846ec63@[]>
To: "Mark Baker" <distobj@acm.org>
Cc: "Stuart Williams" <skw@hp.com>, www-tag@w3.org

>Hey Stuart,
>On 8/13/07, Stuart Williams <skw@hp.com> wrote:
>>  Mark,
>>  Could you elaborate a little more on the distinction that you are making
>>  between 'direct' and 'indirect' reference.
>I just mean what the TAG described here;

Given that someone is asking the question, it might be a reasonable 
inference that they find the description given there less than clear 
(which indeed it is).

>>  An example of each would be
>>  helpful... and particularly one where the 'direct' references refer to
>>  the same thing, but where the corresponding 'indirect' references refer
>>  to different things.
>Hmm, I don't see how such an example would shed any light on my issue,
>but hopefully expanding on the example from AWWW might ...
>Suppose Nadia had two email addresses, nadia-work@example.com and
>nadia-personal@example.com.  She might use each to *directly*
>identify, respectively, her work and personal email inboxes.  However
>the organizers of a conference might be free to use either to
>*indirectly* identify her person.

They are free to use either to refer to her. On the face of it, there 
in nothing to distinguish this kind of reference from any other kind 
of reference, seems to me. What is it, in your view, that makes this 
kind of reference "indirect"? Is this supposed to mean
(a) this reference can't be allowed to count as 'direct' because the 
URI already has a different 'direct' referent, and the TAG insists 
that there can't be more than one of these, so this reference must be 
counted as something other than 'direct', viz., 'indirect';
(b) This reference is 'transferred': the URI actually refers, 
unambiguously, to the mail inbox; but the organizers might us the 
mail inbox as a kind of proxy for the person whose mailbox it is, and 
it is the proxy-transference of reference in this way that makes it 
In case (a), the direct/indirect distinction seems to be purely 
artificial doublespeak, a way to rescue the 'no-ambiguity' ruling 
while admitting that reference can indeed be ambiguous. In case (b) 
it would be better to not call this 'indirect reference' or 'indirect 
identification' at all, because the actual reference/identification 
is quite clear.

>  But I don't believe it would be
>correct for those organizers to state that those two URIs were
>owl:sameAs because they don't know what either of them directly

The semantics of owl:sameAs don't distinguish between direct and 
indirect reference. It assumes only that there is a single mapping 
from names to things. There might be others, of course, in different 

>  Even if the conference organizers minted their own URI for
>Nadia - say, http://example.org/~nadia - and so knew exactly
>(directly) what it identified, it still, IMO, would not be correct for
>them to state that their URI was owl:sameAs either of Nadia's mailto
>URIs, again because they don't know what her URI directly identifies.
>The above assumes that owl:sameAs is defined in terms of direct

Ah, OK. But then since this everywhere else is simply called 
'reference', why muddy the waters?

>, which I think is the only sane interpretation of "same as"
>(same resource).

This is muddled. "Same as" is completely unambiguous. It means "The 
same thing as", aka identity. The question is, what is being stated 
to be identical to what?

>  If owl:sameAs were defined in terms of indirect
>reference, then you'd be able to make silly declarations such as;
>   <http://www.number-10.gov.uk/> owl:sameAs
>      <http://www.homeoffice.gov.uk/> .
>because both of those URIs can be used to indirectly identify the UK 

No, look, you can't have it both ways. Either 'indirect reference' is 
reference or it isn't. If it is, then this assertion can be true, for 
the reason you give. And then reference is ambiguous. But if it 
isn't, then it would be a lot less confusing if y'all used a 
different word for it. Whatever 'indirect reference' is, its 
apparently NOT a kind of reference.


>Mark Baker.  Ottawa, Ontario, CANADA.         http://www.markbaker.ca
>Coactus; Web-inspired integration strategies  http://www.coactus.com

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Received on Monday, 13 August 2007 19:02:49 GMT

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