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Re: Confusion about allValuesFrom property restriction.

From: Jim Hendler <hendler@cs.umd.edu>
Date: Wed, 26 Feb 2003 19:28:28 -0500
Message-Id: <p05200f2bba830be57224@[10.0.1.4]>
To: "Jordan Frank" <jfrank@b-ap.com>, public-webont-comments@w3.org

At 18:52 -0500 2/26/03, Jordan Frank wrote:
>I don't know if this has been previously commented on, but I noticed what
>appears to be a contradiction in section 3.4.1 of the OWL Guide Version 1.0.
>In the first paragraph, you state that
>"The owl:allValuesFrom restriction means that every instance of the class
>must have an instance of the specified property with values that are all
>instances of the specified restriction class."
>
>The part that confuses me is "[...] every instance of the class must have an
>instance of the specified property [...]". My understanding is that a
>property with the allValuesFrom restriction is optional, but if it does
>exist then the restriction applies. The document even goes on to state that
>the implication of the allValuesFrom restriction on the property hasWinery
>in your example is that:
>"For all wines, if they have makers, all the makers are wineries."
>This would lead me to believe that the hasWinery property is optional. In
>fact, a bit further down in the same section you state that
>"The [allValuesFrom restriction] does not require a wine to have a maker. If
>it does have one or more, they must all be wineries.".
>
>I'm guessing that it is the case that an allValuesFrom restriction means
>that the property is optional, so if this is the case I suggest that the
>first statement that I quoted be changed to reflect this. I apologize if
>this has already been brought to your attention.
>
>Cheers,
>Jordan Frank
>eBusiness Applications
>www.ebusinessapplications.ca
>jfrank@b-ap.com

Jordan - many thanks for your comment, we will be sure the editors 
see it.  You are right that allValuesFrom doesn't require a 
cardinality > 0, and the first statement is indeed misleading.
  -JH

-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
http://www.cs.umd.edu/users/hendler
Received on Wednesday, 26 February 2003 19:28:39 GMT

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