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[protege-owl] Protege OWL and restrictions

Mariusz Chmielewski mchmielewski at wat.edu.pl
Mon Apr 19 15:54:59 PDT 2010



> I have been testing several constructions In my ontology to achieve  
> simple situation
> 1.       I have defined 3 Enumeration Classes A1 A2 A3 (each of them  
> with set o f3 individuals I1A1,I2A1,I3A1.. And so on)
> 2.       I have defined a class C1
> 3.       Property C1-A1 C1-A2 C1-A3
> 4.       Then I define two subclasses C1_1 C1_2 of C1 which consist  
> of value restrictions
> a.       AllValuesFrom restriction
> b.      With two optional restriction -  exactly 1 (for mendatory  
> value) or max 1 (for optional value)
>
>
> When I create the individual protégé shows proper form for defining  
> individuals (red border for exactly 1 - no border for max 1) for  
> properties but when I add SomeValesFrom all the form elements have  
> red border.

>Well SomeValuesFrom includes a Minimum Cardinality 1 restriction, so  
>at least one value of the given type is required.  That would explain  
>why there is a red box.


In restrictions list I have (as fund In the protégé OWL tutorial)
complementary AllValuesFrom restriction and SomeValuesFrom - they have
pointed out that OWA states that universal restriction applies also to
individuals without assigned property value of this kind. 



> What is the idea for properly defining optional and mandatory  
> properties to fill while defining class restrictions?

Well, I think that minimum 1 and no minimum value is what you want to  
use for mandatory and optional values.  Note that because of open  
world, individuals with "mandatory" values don't actually need to have  
any particular value specified.

Also, the red box GUI item is a hold-over from the Frame  
representation of Protege and doesn't always work exactly the way you  
might wish when working with OWL ontologies.  In that sense, it is  
probably better not to rely on it.


I would also point out that open world reasoning makes maximum and  
exact cardinalities a bit problematic for reasoning.  Especially when  
you have an exactly 1 restriction, it may make more sense to make sure  
that the Property in question is a FunctionalProperty.

They have been defined as functional but In order to reflect the Real
relational database constructions it is mandatory to provide the
restrictions. I wonder if problems I am having with multiple
Necessery&sufficient blocks are connected with exactly 1 and max 1? All my
defined classes with two or more N&S condition blocks are inconsistent ?

 






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