W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2002

Re: Just say not

From: Jim Hendler <hendler@cs.umd.edu>
Date: Mon, 1 Apr 2002 16:55:03 -0500
Message-Id: <p0510150db8ce86099267@[]>
To: Pat Hayes <phayes@ai.uwf.edu>, "Seth Russell" <seth@robustai.net>
Cc: "RDF-LOGIC" <www-rdf-logic@w3.org>
[snip nearly everything]

  10:39 AM -0800 4/1/02, Pat Hayes wrote:
>Not nearly so obvious to me. Negation is obviously immediately 
>useful, context far less obviously so.

again, depends what the word means - but there are places where being 
able to close some set of assertions might be desirable

>>Seth Russell wrote:
>>Hmmmm ... how come I don't see the big c mentioned in [4] ?
>>[4]  http://www.w3.org/TR/webont-req/
>>What would be the real problems (if any) of this simplicity ?

well, we don't use that word - but one of our objectives was (from [4])

====== begin quote=======
Ability to state closed worlds

     Due to the size and rate of change on the Web, the closed-world 
assumption (which states that anything that cannot not be inferred is 
assumed to be false) is inappropriate. However, there are many 
situations where closed-world information would be useful. Therefore, 
the language must be able to state that a given ontology can be 
regarded as complete. This would then sanction additional inferences 
to be drawn from that ontology. The precise semantics of such a 
statement (and the corresponding set of inferences) remains to be 
defined, but examples might include assuming complete property 
information about individuals, assuming completeness of 
class-membership, and assuming exhaustiveness of subclasses.

     Motivation: Shared ontologies goal
=======end quote=======

which is one interpretation of the term.  We didn't make this a 
requirement because the "remains to be defined" was a little too much 
for us to be willing to commit at this point...

[snip the rest]

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)
AV Williams Building, Univ of Maryland		  College Park, MD 20742
Received on Monday, 1 April 2002 16:55:09 UTC

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