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Re: Despair! The exact meaning of Complement??

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Mon, 28 Feb 2011 09:47:18 +0000
Cc: dja222@hotmail.com, Owl Dev <public-owl-dev@w3.org>, Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>, Pat Hayes <phayes@ihmc.us>
Message-Id: <BE8C4312-309E-4502-9CFA-20D23A35626A@cs.man.ac.uk>
To: Alan Rector <rector@cs.man.ac.uk>
On 28 Feb 2011, at 09:26, Alan Rector wrote:

> On 28 Feb 2011, at 00:30, Pat Hayes wrote:
>>>> And another: Is it allowed to make the most upper class "Thing" equivalent to a defined class?
>> No. Even if it is strictly legal, it would be a very bad idea, as an ontology that did this would be immediately inconsistent with almost every other ontology. 
> Inferring that some class is equivalent to owl:Thing is a not uncommon error.  The simple form is that any class with the definition: 
> 	C EquivalentClass (A or not A)
> is equivalent to owl:Thing. 
> Hopefully no one would do this intentionally,

I can see a case for when you want to package up a set of global constraints under a name. Instead of writing
	owl:Thing SubClassOf: ...complex set of constraints.

You might prefer:
	FriendlyName EquivalentTo: ...complex set of constraints.
	owl:Thing SubClassOf FriendlyName.

(though this can be tricky). It's slightly easier to manipulate, IMHO.

> but it can come about as the result of other inferences.  Matthew Horridge has some difficult-to-spot examples from his work on justifications.    The result is usually a mass of unintended inferences, since everything is inferred to be a subclass of C. 
> In general, a useful heuristic is that, if you find an unexpected inference of equivalence in your ontology, you have probably made a mistake. 

We're still looking for good analogous to "unsatisfiable class" and "incoherent TBox" for the top synonym case. "omnisatisfiable class"? "Vacuous class"? "Borged" tbox? "Incoherent" could still work (as it brings too much together). Overcoherent? Tenacious?

The first step to stigmatizing something is to give it a name :)

"Omnisatisfiable class" seems quite good to me. It states what it is and it nicely relates to "unsatisfiable".

Received on Monday, 28 February 2011 09:47:47 UTC

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