[protege-discussion] Closure Axiom and inferences issues

[Timothy Redmond]

>
> Those instances are supposed to be a member of the 
> "VegetarianPizzaEquivalent1" and "Margherita" classes after the 
> inference process. Those classes use in their definition the Closure 
> Axiom (i.e. ONLY). 


Conceptually your plan with the closure axiom should have worked and no 
sub properties should have been necessary.  If you send the ontology I 
can perhaps have a look and see what went wrong.

-Timothy


On 06/22/2012 07:19 AM, Gabriela Medina wrote:
>
> Hello,
>
> I've been recently using Protégé and I have one question. I have used 
> the Pizza example to see how inferences performed by  reasoners 
> (Pellet, Hermit...) worked. In that sense, I have introduced instances 
> of the "Pizza Class" to see how they were classified after the 
> inference (I have mainly worked with Pellet but i have also used other 
> reasoners). Those instances have the following characteristics:
> 1. One of the instance has a Vegetarian Topping.
> 2. Another of the instances has Mozarella and Tomato Topping.
>
> Those instances are supposed to be a member of the 
> "VegetarianPizzaEquivalent1" and "Margherita" classes after the 
> inference process. Those classes use in their definition the Closure 
> Axiom (i.e. ONLY). However, when i performed the inference, those 
> instances weren't classified as members of the 
> "VegetarianPizzaEquivalent1" and "Margherita" classes.
>
> I have performed several tests to understand how reasoners worked and 
> I have one possible explanation that i would like to confirm with you. 
> Actually I think that when one use an Object Property with a large 
> Range (for example in the Pizza example, the hasTopping property has 
> as a Range the PizzaTopping class) and when one use the Closure Axiom 
> for the definition of class, the reasoner suppose that the instances 
> of the "defined class" could have the all the classes of the Range 
> (i.e. all kind of Pizza Toppings) and NOT ONLY the specified classes 
> precised for the Closure Axiom. In that sense,  the definition of the 
> Margherita Classprecised that this class "hasTopping ONLY 
> (MozzarellaTopping or TomatoTopping)". However, hasTopping property 
> has a very large Range which is "Pizza Topping. For this reason, 
> inference is not performed.
>
> As a solution to this issue,  I have created sub-ObjectProperties such 
> as "hasToppingMargherita" with Domain "Margherita Pizza" Class and 
> with Range "Tomato" and "Mozarella Toppings". This solution worked and 
> instances were classified in their respective classes. Nevertheless I 
> found this solution demands harder modeling efforts. Besides, in that 
> case, it isn't worthy to use the Closure Axiom, since Range will  be 
> already limited in the SubProperty.
>
> What do you think about my explanation? and about my solution? any 
> suggestion?
>
> Thanks in advanced for your reply and for your help,
> Kind regards,
> Gabriela
>
>
>
>
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