Re: How to negate cc:permits, cc:prohibits, cc:requires?
On Fri, Jun 19, 2009 at 7:14 PM, Nathan
Yergler<nathan <at> creativecommons.org> wrote:
> If there are revisions we should consider, I'd be open to proposals.
thanks for your explanations. As far as my own work with ccREL is
concerned, my concerns were mostly theoretical, as I expect most of
our mathematical documents to use the standard CC licenses.
> In all the CC licenses, if Commercial Use is not explicitly
> prohibited, it is considered allowed. We've previously looked at
> expressing this sort of additional information with OWL but haven't
> released anything.
However, I think that this kind of negation as failure is not
consistent with the open world assumption made by OWL and RDFS. If
Alice defines a custom license L in one of her documents and wants to
say that commercial use is allowed, her only choice is to say nothing,
i.e. to leave the RDF triple "L cc:prohibits cc:CommercialUse" out.
But what if Bob somewhere else on the web says "L cc:prohibits
cc:CommercialUse", and then some crawler crawls both Alice's and Bob's
For that reason, I think it would be better to explicitly be able to
state negative facts. Depending on how this is implemented in OWL,
one would be able to say in the ccREL ontology that e.g. "prohibits X"
and "permits X" contradict each other. Then, in the scenario outlined
above, it could still happen that Alice's and Bob's contradicting
facts are merged together, but then any reasonable semantic web