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Re: httpRange-14: some dimensions of space of positions

From: Roy T. Fielding <fielding@gbiv.com>
Date: Tue, 3 May 2005 00:47:49 -0700
Message-Id: <965adacef00743a9e391630933cfb27a@gbiv.com>
Cc: Harry Halpin <hhalpin@ibiblio.org>, www-tag <www-tag@w3.org>
To: Dan Connolly <connolly@w3.org>

On Apr 29, 2005, at 8:34 AM, Dan Connolly wrote:
> What I'm suggesting is that you can coin terms for
> the class "person" (or "agent") and the class "document",
> say that they're disjoint, and say that something
> is in one of them (and hence not the other), hence
> disambiguating between a person an their homepage.
> I can write this to say that I mean for
> http://www.example.org/PatHayes to denote his homepage:
>   foaf:homepage a owl:InverseFunctionalProperty;
>     rdfs:domain foaf:Agent;
>     foaf:range foaf:Document.
>   foaf:Agent owl:disjointFrom foaf:Document.
>   _:somebody foaf:homepage <http://www.example.org/PatHayes>.
> And if somebody else writes
>   adams:HoopyFrood rdfs:subClassOf foaf:Agent.
>   <http://www.example.org/PatHayes> a adams:HoopyFrood.
> then the machine can compute that we disagree.

Yes, and one might even think the disagreement is obvious,
right up to the point where you realize that documents
are also agents, and while they may not have friends they do
occasionally have home pages, and it is the statement that the
two are disjoint that may be in error.

For example, let's consider Tim Bray's blog "ongoing".  Would you
claim that is a document or an agent?  Is it alive?  Does it have
a life span?  Does it have a physical effect on other agents?
Does the fact that ongoing consists of a set of authored entries
that change over time mean it is more like a document or less
like a document?

Does "ongoing" have a homepage, or does it just have a URI?

I won't claim that I have the answer for any of those questions.

httpRange-14 is a statement that those questions have been answered
in a meaningful way by the scheme used to identify the blog.

Regardless, people use URIs to identify resources and don't care
whether or not a computer thinks two poorly-defined sets are
disjoint.  There is no way that a system can determine whether a
user has supplied a URI for the purpose of direct, ontologically
unambiguous identification of a resource, or of simple indirect
identification via whatever URI seems most useful at the time.
That is a problem of reference that will not be solved by changing
the syntax of the identifiers.

Received on Tuesday, 3 May 2005 07:48:05 UTC

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