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Re: [ontolog-forum] Just What Is an Ontology, Anyway?

To: ian@xxxxxxxxxxxxxxxx, "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Mon, 26 Oct 2009 12:30:04 -0500
Message-id: <AC95D8FC-0B70-4249-9581-280E93493510@xxxxxxxx>
On Oct 26, 2009, at 11:43 AM, Ian Bailey wrote:
> Er...what does ontology have to do with automated reasoning ?    (01)

Ever since the term was co-opted (not entirely without warrant) by the  
CS/AI community, a (perhaps the) central motivation has been to  
facilitate automated reasoning on large knowledge bases.    (02)

> The scope of ontology is far wider than that, and there are lots of  
> ontologies out there that are really useful for real world  
> applications, but don't meet the narrow requirements for finite-time  
> reasoning.    (03)

Example being...?  Do you really mean it's in a logic without a proof  
theory?  Or do you simply mean that the ontology is not formally  
specified?  I don't doubt that a semi-formal ontology couldn't be  
useful for, e.g., facilitating a common understanding of a domain  
among human agents.  But, ultimately, complete clarity (and  
computational support) comes only when an informal ontology has been  
rendered in a logical language.  And if you've got a genuine logical  
language, you'll have some sort of proof theory and hence something  
amenable to automated reasoning.    (04)

> On the other hand, there are ontologies out there that have been  
> built only for reasoning, and are no use whatsoever in real world  
> applications...in fact there are rather a lot of these, mostly  
> funded by our taxes, unfortunately.    (05)

So there are bad, well-funded ontologies; nothing new there.    (06)

> I'm not sure a complete proof theory is required either.    (07)

You are right; partial proof theories for well-specified fragments of  
a given logic could also be useful.  The point was that one needs a  
rigorous proof theory for a logic to support any kind of automated  
reasoning.    (08)

> The none-well-founded stuff seems to work quite well (assuming  
> that's what Chris meant by "proof").    (09)

I don't have any clear idea what you have in mind by "none-well- 
founded" stuff.  I'm guessing you mean "non-well-founded" but I'm  
still not sure what you mean.  Perhaps you are alluding to well- 
founded semantics (WFS)?  That is indeed a framework that in general  
does not have a complete proof theory but there are a number of  
interesting completeness results for WFS-based systems when certain  
conditions are imposed on models.    (010)

-chris    (011)



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