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[protege-owl] Inheritance?

Thomas Schneider schneidt at cs.man.ac.uk
Fri Jan 15 01:08:32 PST 2010


On 14 Jan 2010, at 19:59, Thomas Russ wrote:

> I don't normally use Protege 4, so I'm not the best person to answer  
> some of these.
>
> On Jan 14, 2010, at 3:09 AM, Poovendran Moodley wrote:
>
>>> As a simple example, if you define a class
>>>
>>>  50-year-old  ==  Person and (hasValue age 50)
>>
>> I wasn't sure if age should be an object or data property. So I  
>> tried both: as a data property, Bill was inferred as a 50-year-old,  
>> where the class 50-year-old has the equivalence class "Person and  
>> (age value 50)." However, Fred was not inferred to have the data  
>> property of age being 50 (though Fred, of course was inferred to be  
>> a Person since 50-year-old is-a Person).
>
> I'm not sure where you would have to look to find inferred datatype  
> property values using Protege 4.0, but I would expect them to be  
> available somewhere.

Hmm, this is a bit tricky: since most datatypes are infinite, a GUI  
that displays inferred datatype values of individuals would have to  
handle an infinite search space. However, if you specify the value  
you're after, the DL query tab of Protégé 4 will give you the required  
answer. Specify the class expression "age value 50" as the query, tick  
the box "Individual", and hit "Execute". The answers under "Instances"  
will include Fred.

Cheers

Thomas

>
>>> You can then make the following assertions:
>>>
>>>  Fred  type  50-year-old
>>>  Bill  type Person
>>>  Bill  age 50
>>>
>>> Bill will be recognized as belonging to the class "50-year-old".   
>>> Fred will have an inferred property value for "age" of 50.
>>
>>> Where the difference becomes apparent and will diverge from what  
>>> you might get from an object-oriented perspective is if you use  
>>> some of the other restrictions.  Most interesting would be, for  
>>> example the "allValuesFrom" or the "minCardinality" restrictions.
>>>
>>> In Protege 4, the class expression editor doesn't support the  
>>> keywords allValuesFrom or minCardinality. I think I managed to try  
>>> out using allValuesFrom but I'm not sure how to express  
>>> minCardinality.
>
> I think Protege 4 normally uses the more abbreviated Manchester  
> syntax.  In that case
>   allValuesFrom = only
>   minCardinality = min
>
> There is a nice summary table at http://www.co-ode.org/resources/reference/manchester_syntax/
>
>>
>>> If you were to define
>>>
>>>  A  == B and (allValuesFrom P 50-year-old)
>>
>> I used that class A has the equivalence class: B and (P only 50- 
>> year-old). Indeed, i-2 was inferred to be of type 50-year-old. It  
>> didn't gain the data property age 50 but if I used the other  
>> 50YearOld class in the equivalence class (described above) then i-2  
>> did get the "hasValue 50" object property inference as expected.
>
> Sounds like the same issue as above.
>
>>>
>>> and then assert
>>>
>>>  i-1  type  A
>>>  i-1  P  i-2
>>>
>>> then the inference engine will conclude that i-2 must be of type  
>>> 50-year-old, and that information will be available for further  
>>> reasoning.  In particular, the reasoner will figure out that the  
>>> age of i-2 must be 50.
>>>
>>> Instead, if you were to define
>>>
>>>  X = Y and (minCardinality P 3)
>>
>>
>> I suspected that the keyword only could mean allValuesFrom, and it  
>> seemed to work as such. I suspect that the keyword min means  
>> minCardinality but I'm unable to construct a valid expression in  
>> Protege. I'd love to know how it's done :D
>
> Correct on the keyword correspondences.  I think the form you need  
> is "P min 3".
>
>>
>> and then assert
>>
>> i-3 type X
>>
>> then the reasoner will conclude that i-3 has at least 3 values for  
>> property P, but it won't be able to tell you which ones they are.   
>> This is where open world reasoning comes into play.  Even though  
>> there are 3 fillers, they don't have to be specifically  
>> identified.  OWL is quite able to reason with just this partial  
>> information.
>
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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)       |
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   Awful things bought in Nairobi which never look good at home.

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