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Re: questions on assertion

From: Charles McCathieNevile <charles@w3.org>
Date: Mon, 1 Jul 2002 10:37:39 -0400 (EDT)
To: finin <finin@cs.umbc.edu>
cc: Giles Hogben <giles.hogben@jrc.it>, <www-rdf-interest@w3.org>, <www-rdf-logic@w3.org>
Message-ID: <Pine.LNX.4.30.0207011033380.1487-100000@tux.w3.org>

Hmm. Maybe we should think of them as rumours. They might be true, and we can
collect them together to see if they are internally consistent.

We ran into this problem in developing EARL - http://www.w3.org/2001/03/earl
is the out of date homepage - which assumes that different people will make
different claims about the same thing (and also that the same people will
make different claims at different times).

As far as I understand the model an assertion doesn't necessarily have an
author - and for RDF purposes you would assign provenance explicitly in RDF,
so as to avoid the situation of magically adding properties to things.


Charles McCN

On Mon, 1 Jul 2002, finin wrote:

  Giles Hogben wrote:
  >... So the problem I am getting at, is how can say, without creating a logical
  > inconsistency, that one believes a statement in rdf data is false?

  RDF doesn't provide a general way of making negative statements.  Neither
  does DAML+OIL or OWL, though those languages provide some indirect ways of
  making negative assertions (e.g., saying that two classes are disjoint)

  > This is in my view a real problem for applications involved in reputation
  > and trust.

  I agree with you here, though one can do a lot of what's needed with the ability
  to be unable to prove that a fact is true given an ontology and a set of instances.

  > 2. If rdf statements implicitly carry assertion, how can I specify the
  > author of the assertion? That is - does the assertion implied by 1. also
  > imply something about who is making the assertion (is it the author of the
  > document?) - then how do I change that if I want to in a statement like 7.

  I think this is also a weakness that will eventually need to be addressed.  Some
  seem to be happy with the idea of associating rdf triples with the URIs where
  they are found.  But, I think we will need to tie the assertions to an "agent"
  whether that is an individual, a software agent, or an organization.  I imagine an
  ontology that can be used to identify something as an agent and define appropriate
  properties.  One could then add statements to a file that identify the agent to which
  the assertions in the file can be attributed.

Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI  fax: +33 4 92 38 78 22
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Received on Monday, 1 July 2002 10:37:43 UTC

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