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[protege-discussion] Nothing class (newbie question)

Csongor Nyulas csongor.nyulas at stanford.edu
Wed Mar 6 11:55:56 PST 2013


Also, if the reasoner classifies some classes as subclass of owl:Nothing 
it means that those classes are unsatisfiable, or as Matthew said, they 
cannot have any instances. This may be due to some modelling errors in 
your ontology.

Csongor

On 03/06/2013 11:24 AM, Matthew Horridge wrote:
> Hi,
>
> owl:Nothing is interpreted as the empty set.  It does not have any instances.  Because it is interpreted as the empty set, it is a subclass of every other class (since the empty set is a subset of every set).  owl:Thing appears at the top of the class hierarchy, whilst owl:Nothing appears at the bottom of the class hierarchy.  Hope this helps.
>
> Cheers,
>
> Matthew
>
>
>
> On 6 Mar 2013, at 11:12, André Luiz Tietböhl Ramos wrote:
>
>> Hello,
>>
>> What does the Nothing class mean actually?  Assuming its superclasses are inferred, I have many in it and do not know what this aspect means for sure.
>>
>> Thanks in advance.
>>
>> -- 
>> André Luiz Tietböhl Ramos
>> http://www.feng.pucrs.br/~andreltr
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