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Re: why are properties decoupled from classes

From: Xavier Noria <fxn@hashref.com>
Date: Wed, 26 Oct 2005 12:30:06 +0200
Message-Id: <1124F8CE-27A4-4422-9600-E6DA4B7D1255@hashref.com>
To: Semantic Web <semantic-web@w3.org>


On Oct 26, 2005, at 11:47, Jon Hanna wrote:

>
> Xavier Noria wrote:
>
>>> It *is* possible to say that, for example, all people have mothers
>>>
>> In which formalism can you express that?
>>
>
> OWL allows you to define a cardinality on how a property applies to  
> a particular class. <http://www.w3.org/TR/owl-ref/#cardinality-def>

I don't agree there (but maybe my interpretation is wrong, please  
correct me in that case).

My reading of that description is:

     IF a person has a mother THEN it has exactly one

but you can have a person WITHOUT a mother and be consistent (not  
because of the open-world assumption, but because the semantic of  
owl:Cardinality does not imply that *for all*).

-- fxn
Received on Wednesday, 26 October 2005 10:30:49 UTC

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