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Re: Problems with dark triples approach

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 23 Apr 2002 05:31:42 -0400
To: jjc@hplb.hpl.hp.com
Cc: www-webont-wg@w3.org
Message-Id: <20020423053142P.pfps@research.bell-labs.com>
From: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Subject: Problems with dark triples approach
Date: Wed, 17 Apr 2002 14:14:16 +0100

[...]

> There appeared to be agreement at the f2f, that a first order theory (aka my
> solipsistic stuff [2]):
> - does clarify OWL semantics without contradicting our set theoretic
> intuitions
> - is the theory used by DAML+OIL
> - does not contain an adequate theory of classes capturing our set theoretic
> intuitions
> 
> Personally I would feel happier with that solution than paying either of the
> prices that my analsysis suggests for a dark triple based theory of classes:
> viz:
> either:
> - a significant delay to the WG product in order for the SEM focus area to
> undertake a research project
> or:
> - the inability to meaningful take a subPropertyOf the properties used in
> constructing an owl ontology.

Well, I have not yet seen a worked-out version of the solipsistic stuff.
In particular, how are conditionally-existing classes handled in this
approach.

Consider the following query:
	John rdf:type _:1 .
	_:1 daml:onProperty foo .
	_:1 daml:toClass daml:Restriction .
	John rdf:type _:2 .
	_:2 daml:onProperty foo .
	_:2 daml:hasClass _:3 .
	_:3 daml:OneOf _:4 .
	_:4 daml:first _:R1 .
	_:4 daml:rest _:5 .
	_:5 daml:first _:R2 .
	_:5 daml:rest daml:nil .

Which restrictions are to be added to the premises for this sort of query?
Of course, it doesn't matter here, because neither _:R1 nor _:R2 are
interesting, but a larger example could be constructed where it would
matter.

As far as dark triples goes, there are existence proofs that no research
project is needed.  Both Instance OIL and the proposal from Ian, Frank, and
myself could be easily given a (ugly) dark triples syntax.  Also, there is
*no* problem in constructing a property hierarchy in either of these
proposals.

peter
Received on Tuesday, 23 April 2002 05:33:33 GMT

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