Re: questions on assertion

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.