Re: Modularity (was: Linkbases,Topic Maps,and RDF Knowledge Bases -- help me understand, please)

[John Cowan <cowan@mercury.ccil.org>]

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@ccil.org
One art/there is/no less/no more/All things/to do/with sparks/galore
	--Douglas Hofstadter