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RE: RDF and XLink

From: Jeffrey E. Sussna <jes@kuantech.com>
Date: Tue, 13 Apr 1999 16:52:38 -0700
To: "'Paul Prescod'" <paul@prescod.net>, <xlxp-dev@fsc.fujitsu.com>, <www-rdf-comments@w3.org>
Message-ID: <000101be8608$b76eb9e0$5118a8c0@kuantech1.quokka.com>
I struggled with the RDF spec for a long time, trying to understand precisely what was meant by metadata, especially given that the various XML syntaxes for RDF allow you to express almost any legal XML. I concluded by returning to the abstract RDF model; that is really what RDF is. For sanity's sake, I recommend sticking to the concept that RDF expresses triples about resources (i.e., resource X has property Y with value Z). This is an incredibly abstract way to think about information, and you can describe almost any kind of information that way, but it is a concrete representation for information, and not the only one. 

Jeff

-----Original Message-----
From: www-rdf-comments-request@w3.org
[mailto:www-rdf-comments-request@w3.org]On Behalf Of Paul Prescod
Sent: Tuesday, April 13, 1999 2:52 PM
To: xlxp-dev@fsc.fujitsu.com; www-rdf-comments@w3.org
Subject: RDF and XLink


[Simon asks about the relationship between linking and metadata and by
implication about the relationship between XLink and RDF]

If it was RDF you were getting at in your question about "metadata" then I
want to say that RDF seems to use its own definition of metadata which as
far as I know is unique to RDF. Furthermore, the definition is not
explicit in the RDF specification. The definition seems to be 

"machine-understandable information associated with a document in order to
make the data managable."

Machine understandable is implicitly defined to mean "expressed in terms
of logical assertions." (hmmm. is this what mean by human understanding?)

Technologically speaking, then, there is no reason that RDF is restricted
to metadata at all. I think I read something where TimBL said that
metadata is just the *first application* of machine understandability on
the Web. RDF makes more sense with this context. The language is not tied
to metadata, no matter what its title says. I wish that the RDF spec. had
said something like that itself.

According to the definition of link as "an assertion of a relationship",
links are "machine-understandable" assertions. It follows then, that XLink
could either be superceded by or based upon RDF -- whether or not links
are metadata (which depends on definitions and context).

Someone with some time on their hands might experiment with re-encoding
some XLinks as RDF assertions and might even attempt an RDF schema for
XLink. (I don't think that the latter would capture all of the XLink data
model properly...I suspect there would be a meta-level mismatch but it
would be worth a try.)

-- 
 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself
 http://itrc.uwaterloo.ca/~papresco

By lumping computers and televisions together, as if they exerted a 
single malign influence, pessimists have tried to argue that the 
electronic revolution spells the end of the sort of literate culture 
that began with Gutenberg’s press. On several counts, that now seems 
the reverse of the truth.

http://www.economist.com/editorial/freeforall/19-12-98/index_xm0015.html
Received on Tuesday, 13 April 1999 19:52:49 GMT

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