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Confusion about allValuesFrom property restriction.

From: Jordan Frank <jfrank@b-ap.com>
Date: Wed, 26 Feb 2003 18:52:03 -0500 (EST)
Message-ID: <03b201c2ddf2$01e3b6c0$1d0110ac@ROADIE>
To: public-webont-comments@w3.org




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
Received on Wednesday, 26 February 2003 18:57:27 GMT

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