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Re: ACTION-268

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Fri, 30 Jan 2009 16:51:14 +0000
Message-Id: <FC323994-1C1F-4AEC-8563-4A58ED7527E1@cs.man.ac.uk>
To: W3C OWL Working Group <public-owl-wg@w3.org>

On 21 Jan 2009, at 19:31, Bijan Parsia wrote:

> Done with:
> 	 http://www.w3.org/2007/OWL/wiki/index.php? 
> title=Syntax&oldid=17348 [Bijan Parsia]
>
> To:
> 	http://www.w3.org/2007/OWL/wiki/Syntax#Keys

In working on the draft reply, I was wondering if my change was  
enough, or if it should read:

"""A key axiom of the form HasKey( owl:Thing OPE ) is similar to the  
axiom InverseFunctionalProperty( OPE ), the main differences being  
that the former axiom is applicable only to individuals that are  
explicitly named in an ontology, while the latter axiom is also  
applicable to individuals whose existence is implied by existential  
quantification. Furthermore, an inverse-functional property is  
inverse-functional for all assertions using that property, whereas  
keys can be scoped to assertions involving individuals of a certain  
class.""""

Add: """In this way, classes can represent distinct tables with the  
same key name or different versions of the same table directly."""

If this is ok, I'll add it.

Also, I think this is misleading:

"""This makes key axioms equivalent to a variant of DL-safe rules [DL- 
Safe]. Thus, key axioms will typically not affect class-based  
inferences such as the computation of the subsumption hierarchy, but  
they will play a role in answering queries about individuals. This  
choice has been made in order to keep the language decidable."""

DL safe rules require DL safety to be decidable (to a first  
approximation). Keys *do not*. We restrict keys for implementation  
considerations.

Cheers,
Bijan.
Received on Friday, 30 January 2009 16:47:47 GMT

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