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Re: disjointness of numerics

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Wed, 28 Jan 2009 15:58:38 +0000
Message-Id: <13909145-A771-4A4F-ADCC-EB1EC411F6CA@comlab.ox.ac.uk>
Cc: "Michael Schneider" <schneid@fzi.de>, "Sandro Hawke" <sandro@w3.org>, <public-owl-wg@w3.org>
To: Bijan Parsia <bparsia@cs.man.ac.uk>

The semantics of OWL 1 says that values of unsupported datatypes are  
interpreted as some element of a set that is at least as large as the  
union of the interpretations of all the known datatypes and is  
disjoint from the abstract domain. A reasoner implementing Vanilla  
OWL would therefore not find this entailment, but nor would it  
conclude that the two values are necessarily different.

Ian


On 21 Jan 2009, at 16:51, Bijan Parsia wrote:

>
> On 21 Jan 2009, at 16:42, Michael Schneider wrote:
> [snip]
>> I am not sure about the situation in OWL 1. Both datatypes,  
>> xsd:decimal and
>> xsd:double, were not required to be supported, AFAIU. I would  
>> guess that
>> there is some chance that at least /some/ existing OWL 1 DL  
>> reasoners will
>> draw the first conclusion,
>
> Yes, but, arguably, erroneously as they types are disjoint in XML  
> Schema.
>
>> since the two datatypes are pretty common. But I
>> believe that this would then be a proprietary extension w.r.t. the  
>> OWL 1
>> spec (though this extension would not be in conflict with OWL 1 DL).
>
> They are permitted in OWL 1, so it's unclear that one should  
> consider it proprietary. Varying from Schema might be considered such.
>
>> Anyone having better information? (E.g., did old versions of  
>> Pellet draw the
>> first conclusion?)
>
> No, due to disjointness.
>
> Cheers,
> Bijan.
>
>
Received on Wednesday, 28 January 2009 15:59:35 GMT

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