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Re: Question on DL negation

From: Vaughan Pratt <pratt@cs.stanford.edu>
Date: Wed, 07 Mar 2007 12:28:12 -0800
Message-ID: <45EF205C.5010802@cs.stanford.edu>
CC: semantic-web@w3.org, public-owl-dev@w3.org

Bijan Parsia wrote:
> Well, disjointness is *weaker* than full negation. For example, in OWL, 
> A disjointWith B is just syntactic sugar for A subclassof complementOf(B).

Are there technical (e.g. computational complexity) benefits to this 
definition over the more usual (and more constructive) definition in 
terms of emptiness of intersectionOf(A,B)?

This is a non-issue as long as the semantics of set operations remains 
Boolean, where the two definitions are trivially equivalent.  However it 
may be useful sometimes to use less than the full gamut of Boolean 
operations, and it would be nice if constructive concepts like 
disjointness didn't then disappear merely because they'd been defined 
using nonconstructive concepts like complementOf.  (Sorry if I seem to 
be nagging about trivialities.)

Vaughan Pratt
Received on Wednesday, 7 March 2007 20:28:32 GMT

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