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RDF and URIs (was Re: Modularity, et al.)

• From: Wayne Steele <xmlmaster@h...>
• To: xml-dev@l...
• Date: Sat, 07 Apr 2001 23:37:09 -0700

This all seems solvable except for the RDF part.

I could envision a way for a resource to specify (when retrieved) "This is
my Canonical URI" - then to test identity you can retrieve the resources and
see what they say.

Supplement this with some agreeable algorthims, for instance that
"http://example.org/doc#foo" is equivalent to
"http://example.org/doc#xpointer(foo)", and I think a pretty good 80/20
point for URI identity can be reached.

But RDF is the problem, because it has a "special" way of looking at URIs.

I've examined RDF, and have considered using it, but this flaw is always the
biggest stumbling block.

Is there any hope for resolving this RDF/URI infidelity?

-Wayne Steele

--------------------

From: John Cowan <cowan@m...>
To: "Steven R. Newcomb" <srn@c...>
CC: cowan@m..., chris.angus@b...,
xml-dev@l...
Subject: Re: Modularity (was: Linkbases, Topic Maps,and RDF Knowledge Bases
-- help me understand, please)
Date: Sun, 08 Apr 2001 01:20:18 -0400 (EDT)

Steven R. Newcomb scripsit:

>Actually, fetching the resources does not, in the general case, permit us 
>to determine that the resources have the same identity.

Oh yes, I know.  I hammered on that point over and over
on xml-uri among other places:

Octet identity of entity bodies is neither
necessary nor sufficient for identity of
resources.

The official line is that resources are identical
iff their URIs are identical, although I take a
more relaxed view: two URIs may refer to the same
resource if the owner says so.  For example,
ftp://ftp.reutershealth.com/home/internal and
http://ftp.reutershealth.com:8181/home/internal
are according to me the same resource.
(Don't bother going there.)

But I was addressing a different point: namely, the undecidability
of whether two syntactically different XPointers point to the
same part of a given document without examining the document.
For XLink purposes, they are the same if they refer to the
same thing in document; for RDF purposes, they are the
always different.

--
John Cowan                                   cowan@c...


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