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[protege-owl] does protege allow this kind of check consistency?

Thomas Schneider schneidt at cs.man.ac.uk
Thu Apr 29 08:36:47 PDT 2010


On 29 Apr 2010, at 16:30, Sara Paiva wrote:

> Thank you Thomas.
> In my specific case, with this small ontology I can´t make the  
> classifier to tell me that my class is unsatisfiable.
>
> Do i run the "Classify" option in "Reasoner" menu?

Yes, but first you have to specify a reasoner (which will  
automatically trigger classification). Then you can see the result in  
the "inferred class hierarchy" pane, and the unsatisfiable classes are  
marked read and shown to be subclasses of Nothing.

>
> As for the properties i created them just like i mentioned below  
> "Equivalent classes" like:
>
> dp_nr_pages value 1
> dp_nr_pages value 2
>
> is this correct?

Sorry, I misunderstood your example. Only declaring two different  
values for the same property doesn't suffice as long as you haven't  
said that only one value is allowed. So either you declare dp_nr_pages  
to be functional, or you say that every book can have at most one  
dp_nr_pages value by making Book a subclass of dp_nr_pages max 1  
Thing. It then suffices for the unsatisfiability that your above two  
axioms are subclass axioms, rather than equivalent classes axioms.

Cheers

Thomas

>
> thanks again.
>
>
>
> On Thu, Apr 29, 2010 at 4:26 PM, Thomas Schneider <schneidt at cs.man.ac.uk 
> > wrote:
>
> On 29 Apr 2010, at 16:12, sop wrote:
>
>
> Hi everyone?
>
> I have been looking for owl class descriptions and i have doubts  
> regarding
> the check consistency that is possible to perform in protege.
>
> suppose i have a class "book" with a datatype property "nr_pages".
>
> Is it possible to add restrictions like "nr_pages value 1" and  
> "nr_pages
> value 2" in such a way that the classifier can see that this is an
> inconsistent class (never will have instances) has no instance can  
> obey the
> two restricitons.
>
> Sure, you can do this. But please bear in mind that a class forced  
> to have no instances is called unsatisfiable, whereas  
> (in)consistency is a property of ontologies. If O is inconsistent,  
> then classification becomes meaningless and standard reasoners  
> usually produce an error message. (There's paraconsistent reasoning  
> though, but that's for a new thread.) Unsatisfiability of a class C  
> can be produced in many different ways, for instance by saying that  
> C is the subclass of two disjoint classes, directly by saying C  
> subClassOf owl:Nothing, or more indirect ways ..... Unsatisfiability  
> is sometimes called incoherence too.
>
> Cheers
>
> Thomas
>
>
>
>
> Thanks a lot.
>
> -- 
> View this message in context: http://protege-ontology-editor-knowledge-acquisition-system.136.n4.nabble.com/does-protege-allow-this-kind-of-check-consistency-tp2075649p2075649.html
> Sent from the Protege OWL mailing list archive at Nabble.com.
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> ----------------------------------------------------------------------+
> |  Dr Thomas Schneider                    schneider (at)  
> cs.man.ac.uk  |
> |  School of Computer Science       http://www.cs.man.ac.uk/ 
> ~schneidt  |
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> |  University of  
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> Sconser (n.)
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>  anyone more interesting about.
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>                  Douglas Adams, John Lloyd: The Deeper Meaning of Liff
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+----------------------------------------------------------------------+
|  Dr Thomas Schneider                    schneider (at) cs.man.ac.uk  |
|  School of Computer Science       http://www.cs.man.ac.uk/~schneidt  |
|  Kilburn Building, Room 2.114                 phone +44 161 2756136  |
|  University of Manchester                                            |
|  Oxford Road                                             _///_       |
|  Manchester M13 9PL                                      (o~o)       |
+-----------------------------------------------------oOOO--(_)--OOOo--+

Sconser (n.)
   A person who looks around them when talking to you, to see if there's
   anyone more interesting about.

                   Douglas Adams, John Lloyd: The Deeper Meaning of Liff







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