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Re: some x has only y

From: Matthew Pocock <matthew.pocock@ncl.ac.uk>
Date: Wed, 12 Mar 2008 16:32:39 +0000
To: "Swanson, Tim" <tim.swanson@semanticarts.com>
Cc: public-owl-dev@w3.org
Message-Id: <200803121632.40134.matthew.pocock@ncl.ac.uk>

> you would not be creating an inconsistency. Instead, you would be implying
> that :BeerDrinkingThatLeadsToKaraoke is an empty class (i.e. equivalent to
> owl:Nothing). At this point, we haven't actually REQUIRED that the members
> of the class exist.

Hi,

The model-theoretic structure within which OWL and other DLs are framed 
makes 'consistent' eqivalent to being disjoint from Nothing. So, every class 
is either inconsistent, or is capable of having instances. Of course, in a 
particular situation, you may not know anything about those existances other 
than that it is possible for them to exist. That is, you may have no 
assertions naming any of these individuals in your knowledge-base.

So, consistent(x) == disjoint(x, Nothing)
And, inconsistent(x) == subclassOf(x, Nothing)

Hope this helps.

The point I was trying to make in my post was that classes like "Beer drinking 
that leads to karaoke" probably capture the logic needed, but they are ugly 
in that we are really trying to make a statement about possibilities 
associated with beer drinking but have had to invent this sub-type of beer 
drinking to attach this knowledge to.

Anyhoo

Matthew
Received on Wednesday, 12 March 2008 16:32:56 GMT

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