- From: Tim Berners-Lee <timbl@w3.org>
- Date: Tue, 2 Dec 2003 10:39:29 -0500
- To: Walden Mathews <waldenm@optonline.net>
- Cc: www-tag@w3.org, "Williams, Stuart" <skw@hp.com>, Mark Baker <distobj@acm.org>
On Dec 1, 2003, at 14:15, Walden Mathews wrote:
> It seems to me that the Architecture of the World Wide Web
> has to make a decision as to whether there is such a thing as
> indirect identification at the architecture level, and if so formalize
> what that is.
The problem was just that when we said "only use URI to identify the
one thing", a lot of people responded with a counter-example of the
person "identified" by their mailbox. So the counter-example was only
in so as to say, "No, we don't mean that". If we have to formalize
everything that we don't mean, then we would end up extending the
architecture document indefinitely!
The only way i can think of of making it clearer is to use say NTriples.
Direct identification:
here the same URI is use twice to identify the same thing,
which is a person called fred.
card:i rdf:type contact:Person.
card:i foaf:aka "fred".
Misuse:
Here the URI card <http://www.w3.org/> is used to
identify two distinct concepts, with resulting confusion.
<http://www.w3.org> a :Consortium.
<http://www.w3.org> dc:created "1994".
<http://www.w3.org/> a :WebPage.
<http://www.w3.org> dc:created "2003-12-01".
Indirect "identification":
_:x rdf:type contact:Person.
_:x contact:mailbox <mailto:foo@example.com>.
<foo.html> dc:creator _:x.
_:y contact:givenName "Frederick".
_:y contact:mailbox <mailto:foo@example.com>.
_:y foaf:aka "fred".
contact:mailBox rdf:type owl:inverseFunctionalProperty.
in this example, the fact that contact:mailbox is an inverse function
property (erstwhile unambiguous property), one can infer that the
unlabeled concepts _:x and _y are the same thing. This is equivalent of
the way databases are typically used with keys.
(I don't think that this level of detail is necessary in the
architecture document - it would be useful maybe in a finding.)
Tim
> Otherwise, beyond saying "don't do that" about using URI to
> identify more than one resource, I don't think there is anything
> to say, and one shouldn't try.
>
> Sorry to keep chiming in...
>
> Walden
Received on Tuesday, 2 December 2003 10:39:32 UTC