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cc-metadata - Re: [cc-metadata] How to negate cc:permits, cc:prohibits, cc:requires?

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Subject: discussion of the Creative Commons Metadata work

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  • From: Patrick Peiffer <peiffer.patrick AT gmail.com>
  • To: discussion of the Creative Commons Metadata work <cc-metadata AT lists.ibiblio.org>
  • Subject: Re: [cc-metadata] How to negate cc:permits, cc:prohibits, cc:requires?
  • Date: Sat, 20 Jun 2009 00:39:36 +0200

Hi,

I'm definitely not a semantic web specialist but these "Open World vs. Closed World issues" were raised in the W3C team comment on ccREL, http://www.w3.org/Submission/2008/02/Comment

Is this a liability for integrating ccREL into an RDFS / OWL sematic environement?

If yes, what does it take to change that? Nathan, how far did you go with OWL and what stopped you?

Best, Patrick Peiffer
cc-Luxembourg



On Fri, Jun 19, 2009 at 10:37 PM, Christoph Lange <ch.lange AT jacobs-university.de> wrote:
Hi Nathan,

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
definitions?

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
software would _report_ this contradiction.

Not sure if you agree with that reasoning, and, if so, what you'd like
to do.  There is not so much traffic on this list, are there any
semantic web experts around?

Cheers,

Christoph

--
Christoph Lange, http://de.wikipedia.org/wiki/Benutzer:Langec, ICQ# 51191833
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