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[protege-discussion] protege-discussion Digest, Vol 80, Issue 7

André Luiz Tietböhl Ramos andreltramos at
Wed Mar 6 13:36:01 PST 2013


Thanks for the quick reply!  Read below my comments please.


Andre Luiz

On Wed, 2013-03-06 at 12:04 -0800,
protege-discussion-request at wrote:

> Message: 2
> Date: Wed, 6 Mar 2013 11:24:58 -0800
> From: Matthew Horridge <matthew.horridge at>
> To: User support for Core Protege and the Protege-Frames editor
> 	<protege-discussion at>
> Subject: Re: [protege-discussion] Nothing class (newbie question)
> Message-ID: <AA4D44AE-AFEA-4007-A701-6D07A09BC891 at>
> Content-Type: text/plain; charset=iso-8859-1
> Hi,
> owl:Nothing is interpreted as the empty set.  It does not have any instances.  Because it is 
> interpreted as the empty set, it is a subclass of every other class (since the empty set is a 
> subset of every set).  owl:Thing appears at the top of the class hierarchy, whilst owl:Nothing 
> appears at the bottom of the class hierarchy.  Hope this helps.

Yes, it does.  I don't think this matters much though but the Nothing is
shown in the top of the tree and in red.  Since I'm just beginning  I'm
modeling as much as I can using classes and leaving individuals for a
step later.  In other words, how to define an instance although at this
point I don't need them AFAIK?

Message: 4
Date: Wed, 06 Mar 2013 11:55:56 -0800
From: Csongor Nyulas <csongor.nyulas at>
To: protege-discussion at
Subject: Re: [protege-discussion] Nothing class (newbie question)
Message-ID: <51379F4C.80909 at>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Also, if the reasoner classifies some classes as subclass of
it means that those classes are unsatisfiable, or as Matthew said, they 
cannot have any instances. This may be due to some modelling errors in 
your ontology.


Interesting opinion...  What kind of modeling errors could there be?
Should I understand my modeling is somewhat flawed then?  As it is it
seems ok to me even though I'm from more computer programming/modeling
focus, UML specifically.

Andre Luiz Tietbohl Ramos 
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