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Re: Possible semantic bugs concerning domain and range

From: Jim Hendler <hendler@cs.umd.edu>
Date: Mon, 30 Sep 2002 07:30:50 -0400
Message-Id: <p05111712b9bde435ed3d@[10.0.1.2]>
To: "Christopher Welty" <welty@us.ibm.com>, pat hayes <phayes@ai.uwf.edu>
Cc: Ian Horrocks <horrocks@cs.man.ac.uk>, www-webont-wg@w3.org, www-webont-wg-request@w3.org

At 9:04 PM -0400 9/29/02, Christopher Welty wrote:
>Pat,
>
>OK, I (at least) get it.  So if this is the semantics of ranges in rdfs
>(is it?), then probably we should not use rdfs ranges for OWL.  OWL is
>supposed to be based on description logics, which are a decidable fragment
>of FOL (not the only one, btw).

Forgive me Chris, but I have no idea where you get the idea that OWL 
is "supposed to be based on description logics" -- that is not what 
our charter says, that is no where in our requirements statement. 
Some members of the group believe this desirable because of the 
performance factors of DLs.  This has not been recorded as group 
consensus to my knowledge.

>   You can say all you want about the
>expressive limitations of DLs, and you can point out an infinite number of
>things they can't do.  I've thrown them away a bunch of times when I
>absolutely needed more. But if you can say what you want to say within
>their expressive limits, they you can be assured you're going to get
>answers.  Take one step over that line and ba-da-bing! - you're gone.
>
>As an ontology designer, I would absolutely love to be unfettered in my
>expressive ability.  In fact, I usually go ahead and use nth order logic
>with modal quantifiers and all manner of cool stuff.  I love variadic
>predicates, too.    But as a system builder, I also want to know what the
>most is I can say and still be guaranteed a result.
>
>So, anyway, seems to me this group is already committed to producing a
>standard based on a language that is sound, complete, and decidable.

Chris - again, please read our documents before you say these things 
- we committed only to what is stated in our reqs documents [1]. 
Decidability was an "objective" - meaning we were not sure if we 
could achieve it.  So far we have not met all our requirements - 
until we do, it is wrong to focus on objectives or to focus on one 
objective to the exclusion of all the others.

>   So we will have to lose the wild-west syntax and stick with what the DL
>guys
>know how to implement.  All the entailments apparently help speed things
>up.


Stating this as your own position is just fine.  Stating it as group 
consensus is incorrect



[1] http://www.w3.org/TR/webont-req/
-- 
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 Monday, 30 September 2002 07:31:18 GMT

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