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Re: importing and entialment

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Tue, 22 Oct 2002 09:39:42 -0400
Message-ID: <3DB5551D.88918730@cse.lehigh.edu>
To: Jeremy Carroll <jjc@hpl.hp.com>
CC: www-webont-wg@w3.org

Jeremy Carroll wrote:
> 
> Jeff:
> > [ Msg about HTTP 404 and logic ]
> 
> I think you don't mean 404; 500 might be better.
> 
> 404 is document not found, which is used mainly when the URL is bad.
> A 500 server error gets returned when something has gone wrong typically in
> the way the server is working.
> 
> In your example:
> [[
> Document A:
> Man subclassOf Mortal
> 
> Document B:
> B imports A
> Socrates type Man
> ]]
> 
> typically when we get a 404 it would be because of a typo: we wrote A' instead
> of A. In which case there is no logic entailment.
> 
> I think a detailed study of which http error codes map to which sort of
> logically state should be outside the scope of what we do - but I agree with
> your general point that temporary network conditions should not impact the
> logical validty of an entailment. 404 is not temporary though.
> 
> Jeremy

Jeremy,

Thanks for the clarification about 404 errors. However, I think that it
is still desirable to say that if the import "fails," any inferences are
inherently incomplete. Whether it was because the author mistyped the
URL or because the document being referenced was moved by its owner,
there is something that the author of the importing document wants
referenced, but the deductive system is unable to take it into
consideration. I believe saying the inferences are incomplete is much
more graceful than having a defined error condition in such cases
(although specific systems are free to raise warnings or errors in such
cases). However, I believe an error condition is still better than just
saying "well let's assume the imports statement refers to an empty
document."

Jeff
Received on Tuesday, 22 October 2002 09:39:46 GMT

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