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[protege-owl] Please disambiguate property notation 'A = (p has x)' et al.

Patrick McCrae patrick.mccrae at informatik.uni-hamburg.de
Wed Oct 29 02:25:57 PDT 2008


Thanks for your in depth explanation, Timothy.

I am not sure, however, I know how to interpret the notation you use 
correctly. To disambiguate, I have added natural language paraphrases 
below each formula. Could you please indicate briefly which of my 
paraphrases are correct?

> > Please let me know why you say it is generally not a good idea to  
> > define a class via a propery as in 'A = (p has x)'.
>   
Paraphrase 1.1:
'A' is the set of all classes that have one or more property relations 
'p' of which at least one takes value 'x'.

(Or is it Paraphrase 1.2: 'A' is the set of all classes that, if they 
have one or more property relations 'p', then at least on of them takes 
value 'x'. ?)
> This always comes down to a question of meaning.  If 'A = (p has x)'  
> is exactly what you mean then this is how the definition should be  
> written.  The trouble is that sometimes such statements are too strong  
> - they need to be bounded.  So it may be that an assertion like
>
> 	A = B that (p has x)
>   
Paraphrase 2.1:
'A' is the set of all subclasses of 'B' that also have one or more 
property relations 'p' of which at least one takes value 'x'.

(Or is it Paraphrase 2.2: 'A' is the set of all subclasses of 'B. If 
that class also has one or more property relations 'p', at least one of 
them takes value 'x'. ?)

> is what you really wanted.  This is less extreme for the existential  
> restrictions than for the universal restrictions.  Thus
>
> 	A = p all C
>   
Paraphrase 3.1:
'A' is the set of all classes that have at least one property 'p'. All 
values of 'p' are from class 'C'.

(Or is it Paraphrase 3.2: 'A' is the set of all classes. If the class 
also has one or more property relations 'p' then all values of 'p' must 
be from class 'C'. ?)
> is almost always an incorrect definition.   It means in particular  
> that if an individual has no p property value then that individual is  
> in A.
>   
If I understand correctly, this conclusion can only be arrived at with 
Paraphrase 3.2.

Thanks for your clarification!

Regards -

Pat
> -Timothy
>
>
> On Oct 23, 2008, at 1:19 PM, Patrick McCrae wrote:
>
> > Thanks for your response, Timothy.
> >
> > Please let me know why you say it is generally not a good idea to  
> > define a class via a propery as in 'A = (p has x)'.
> >
> > I am asking because in my ontology I have defined several helper  
> > classes in this way and am accessing their inferred contents via the  
> > OWL API.
> >
> > Thanks and regards -
> >
> > Pat
> > _______________________
> >
> > Patrick McCrae
> >
> > CINACS Graduate Research Group
> > Department of Informatics
> > Hamburg University
> > Vogt-Kölln-Straße 30
> > 22527 Hamburg, Germany
> >
> > patrick.mccrae at informatik.uni-hamburg.de
> > fon: +49 . 40 . 428 83 - 23 60
> > fax: +49 . 40 . 42883 - 2515
> >
> >
> > Timothy Redmond wrote:
> >>
> >>
> >>> I was now hoping that when I create an instance of the above  
> >>> class, that instance would have the very same property. This,  
> >>> however, turned out not to be the case. It seems that such class  
> >>> properties are not propagated by inheritance.
> >>
> >> How did you conclude this?  I may have misunderstood but this is  
> >> something that a reasoner can deduce.
> >>
> >> To make sure that I am understanding, let me give an example.  I  
> >> can do this example in Protege 4.  Let's say that I have a class A,  
> >> an object property p and an individual, x.  I make a definition
> >>
> >>     A = (p has x).
> >>
> >> (This is not generally a very good definition but that is another  
> >> story).  Now I add an individual y in the class A.  I select a  
> >> reasoner (pellet, say) and select classify.  In the individuals  
> >> tab, I select the individual y and then under Object Property  
> >> Assertions, I will see a highlighted item " p x ".  This  
> >> highlighted item says that x is a p-value of y.  The fact that it  
> >> is highlighted means that this was one of the things that the  
> >> reasoner inferred.
> >>
> >> -Timothy
> >>
> >>
> >>
> >> On Oct 1, 2008, at 1:54 PM, Patrick McCrae wrote:
> >>
> >>> Dear Protege List -
> >>>
> >>> Can anyone please help me with the following modelling question  
> >>> today:
> >>>
> >>> In Protege 4 I have created a class which is defined by the property
> >>> has_Lexicalisation value Lex_word.
> >>> This is analogous to
> >>> has_Lexicalisation has Lex_word
> >>> in the Protege 3.x world.
> >>>
> >>> I was now hoping that when I create an instance of the above  
> >>> class, that instance would have the very same property. This,  
> >>> however, turned out not to be the case. It seems that such class  
> >>> properties are not propagated by inheritance.
> >>>
> >>> I am hence wondering how I can inherit properties of the above  
> >>> kind from the class to its individuals.
> >>>
> >>> Thanks in advance for your help!
> >>>
> >>> Best regards -
> >>>
> >>> Pat
> >>> _______________________
> >>>
> >>> Patrick McCrae
> >>>
> >>> CINACS Graduate Research Group
> >>> Department of Informatics
> >>> Hamburg University
> >>> Vogt-Kölln-Straße 30
> >>> 22527 Hamburg, Germany
> >>> _______________________________________________
> >>> protege-owl mailing list
> >>> protege-owl at lists.stanford.edu
> >>> https://mailman.stanford.edu/mailman/listinfo/protege-owl
> >>>
> >>> Instructions for unsubscribing: http://protege.stanford.edu/doc/faq.html#01a.03
> >>
>
>   
>
> -- 
> _______________________
>
> Patrick McCrae 
> <http://cinacs.informatik.uni-hamburg.de/index.php?option=com_content&task=view&id=17&Itemid=85> 
>
>
> CINACS Graduate Research Group
> Department of Informatics
> Hamburg University
> Vogt-Kölln-Straße 30
> 22527 Hamburg, Germany
>
> patrick.mccrae at informatik.uni-hamburg.de
> fon: +49 . 40 . 428 83 - 23 60
> fax: +49 . 40 . 42883 - 2515

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