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Re: Concise Bounded Descriptions - updated, expanded, stand-alone definition

From: Karsten Otto <otto@math.fu-berlin.de>
Date: Fri, 20 Aug 2004 12:07:53 +0200 (CEST)
To: Patrick.Stickler@nokia.com
cc: www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.56.0408201126180.3244@hobbes.mi.fu-berlin.de>

On Thu, 19 Aug 2004 Patrick.Stickler@nokia.com wrote:

> A draft of an updated, expanded, stand-alone definition for Concise
> Bounded Descriptions is now available
>
>   http://swdev.nokia.com/uriqa/CBD.html
>
[snip]

Great to have this on its own page as a point of reference!
However, I have a problem with the new concept of the inverse functional
bounded description: It requires that both the sending and receiving
agents are schema/ontology-aware, and also that they share the same
schema/onology-knowledge, in order to correctly create and interpret a
CBD.

For once, the sender needs to know that a given predicate is an
owl:InverseFunctionalProperty, so it can pick the "if"-branch of the
IFBD definition for an anonymous resource. However, this knowledge
may not always be available, e.g. in case of a simple semantic web
crawler. AFAIK the issue of finding all schemata/ontologies for a given
RDF graph is not solved in general yet - or is it?

Furthermore, the receiver also needs to know that a given predicate
is an IFP. This is a more serious issue, as it needs this to determine
whether the "if"- or the "else"-branch of the IFBD definition was picked
by the sender. In the "else" case, it already has all known statements,
but in the "if" case it might need to issue another query (by IFP).
Consequently, if the IFP is unknown to the receiver, it might falsely
conclude that it already got all information the sender had on the
resource.

I see two possible solutions to this problem: The CBD could contain
the relevant "ppp rdf:type owl:InverseFunctionalProperty" statements,
or indicate all relevant ontologies by way of owl:includes.
However, neither solution is viable for RDF-only cases, such as
querying the aforementioned simple spider agent.

By the way this seems to be a more general case of the "crossing layer
boundaries"-problem previously discussed (but not solved) in another
mailing list thread [1].

Regards,
Karsten Otto

[1] http://lists.w3.org/Archives/Public/www-rdf-interest/2003Sep/0082.html
Received on Friday, 20 August 2004 10:07:57 UTC

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