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Re: comments on RDF mapping

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 02 Nov 2007 08:28:40 -0400 (EDT)
Message-Id: <20071102.082840.124047162.pfps@research.bell-labs.com>
To: jjc@hpl.hp.com
Cc: public-owl-wg@w3.org

It is indeed true that in the OWL 1.0 DL direct semantics that 

	SameIndividual(a b)

entails neither

	EquivalentClasses(a b)

nor

	EquivalentProperties(a b)

Part of the reason for this is that no DL reasoner of the time had the
reasoning processes to provide this sort of inference, nor could any be
easily changed to provide it.  Another part of the reason is that when
couched in DL language, the entailment is not intuitive.

These non-entailments are carried over into OWL 1.1.  I am unaware of
any current performance DL reasoner that would support this sort of
inference.

Peter F. Patel-Schneider



From: Jeremy Carroll <jjc@hpl.hp.com>
Subject: Re: comments on RDF mapping
Date: Mon, 29 Oct 2007 18:00:08 +0000

> I think the best way to address punning is by stating the requirement 
> and looking at whether:
> 
> a) this requirement is a requirement, and how widespread
> b) whether punning meets this requirement
> 
> The only articualtion of the requirement that I am familiar with is:
> 
> http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.19-Classes-as-instances
> 
> 
> During the earlier group I felt that it was understood that the 
> requirement was not just that you could use the same name for a class as 
> for an instance, but that some logical consequences would follow.
> 
> for example
> http://www.w3.org/TR/owl-test/byFunction#sameAs-001
> 
> This is an OWL 1.0 Full entailment, which (perhaps with minor syntactic 
> change) would become an OWL 1.1 DL non-entailment (if I have understood 
> punning semantics correctly).
> 
> This seems like a divergence away from OWL 1.0 balance between Full and 
> DL, and also a divergence away from what I believe the requirement of 
> classes as instances is. If two items are the same instance, then they 
> are necessarily the same class.
> 
> The tests that I think express the punning issue are:
> 
> 
> <a> owl:sameAs <b>
> 
> entails
> 
> <a> owl:equivalentClass <b>
> 
> 
> and
> 
> 
> <a> owl:sameAs <b>
> 
> entails
> 
> <a> owl:equivalentProperty <b>
> 
> 
> I currently believe that the member submission OWL 1.1 semantics has 
> these both as non-entailments, and that a requirements doc for the use 
> case of using an instance URI as a class URI or an instance URI as a 
> property URI would have these entailments as holding.
> 
> (Obviously it is possible to give a post hoc rationale in which these 
> entailments are unimportant - it is easier to tell whether or not a 
> design meets a requirement if the requirement is written down, before 
> the design is)
> 
> Since the OWL 1.0 design solves this problem, in the manner given by
> 
> http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.19-Classes-as-instances
> [[
> Part of OWL Full.
> ]]
> (and syntactically excluded from OWL DL)
> 
> I personally see a variation in which this becomes
> 
> "Part of OWL Full; syntactically permitted in OWL DL, but with weaker 
> semantics."
> 
> as a backward step
> 
> Jeremy
Received on Friday, 2 November 2007 12:41:23 GMT

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