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Re: Unique names assumption

From: Jim Hendler <hendler@cs.umd.edu>
Date: Fri, 2 Aug 2002 08:52:10 -0400
Message-Id: <p05111702b97030abc299@[10.0.1.4]>
To: David Allsopp <d.allsopp@signal.qinetiq.com>, public-webont-comments@w3.org

At 11:02 AM +0100 8/2/02, David Allsopp wrote:
>With reference to the Feature Synopsis
>http://www.w3.org/TR/owl-features/ :
>
>>  differentIndividualFrom: Two individuals may be stated to be 
>>different from each other. For example, the individuals Frank and 
>>Deborah may be stated to be different from each other. From this, 
>>the reasoner can deduce that Frank and Deborah refer to two unique 
>>individuals. Thus, if the individuals Frank and Deborah are both 
>>values for a property that is stated to be functional (thus the 
>>property has at most one value), then there is a contradiction. 
>>Stating differences can be important in systems such as OWL (and 
>>RDF) that do not assume that individuals have one and only one 
>>name. For example, OWL with no additional information, will not 
>>deduce that Frank and Deborah refer to distinct individuals.
>
>Does this not lead to an explosion of properties in applications where
>the majority of individuals do have unique names? I.e. for N individuals
>we would require N(N-1)/2 differentIndividualFrom properties?
>
>Regards,
>
>David Allsopp

David - this is a good point, and one which we are concerned about - 
it is on our issues list - see [1] for a discussion - we have not yet 
resolved this issue.
  -Jim H.

[1] 
http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.18-Unique-Names-Assumption-Support-in-OWL

-- 
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 Friday, 2 August 2002 08:52:16 GMT

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