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rdf inclusions (was Re: DAML Level of Effort for FY03-FY05)

From: Sandro Hawke <sandro@w3.org>
Date: Sun, 21 Apr 2002 13:06:18 -0400
Message-Id: <200204211706.g3LH6JD17020@wadimousa.hawke.org>
To: Drew McDermott <drew.mcdermott@yale.edu>
cc: drager@bbn.com, www-rdf-logic@w3.org

> Is it supposed to be the case that just mentioning an ontology's
> namespace means that the file uses that ontology? 

The namespace declaration is just syntactic sugar (it doesn't appear
in the N-Triples generated, etc), but if we phrase your question
differently, the point remains important:

   Does using a term defined by some ontology O in some
   RDF graph G mean that G is using O?

I think a "yes" answer would be convenient but wrong in the long run.

I think this is a special case of broader RDF question:

   Does using a term T in RDF graph G mean that the author
   of G believes and and all other RDF graphs which use T?  (obviously
   not....)    ... that the author of G believes some graph which
   "defines" T?  (maybe, if we could figure out what "defining"
   meant; is that what you get when you try to GET from the namespace
   address?)

My working answer is this:  when you're looking at a graph G and you
come across a term T...

   1.  Other graphs which contain T may have relevant information,
       but you can't assume the author of G knew about them or
       believes in them.  If you have your own reasons to trust both
       them and the author of G, you should use the merged graph.

   2.  The author of G should be able to state a belief of some 
       other graph, of which the ontology O is a special case.  This
       is something like daml:includes, but more general.  Something
       like "<http://address.of.some.RDF.content> rdf:type
       rx:TruePage."

   3.  EricP (and SOAP) keep saying they want "must-understand"
       messages, which is relevant here, because you might want to say
       "you must subscribe to O before looking at my message; if you
       don't then you'll understand my message incorrectly".   I don't
       have a use case for this, but I do have solution, which is that
       you provide your graph in the form "if O then G", so the reader
       must understand both your "if...then" vocabulary and O before
       it even sees G.

I know we're working in some different areas, but I hope this still
made some sense.

    -- sandro
Received on Sunday, 21 April 2002 13:11:11 GMT

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