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[protege-owl] R: Re: trouble in testing consistency

Thomas Russ tar at ISI.EDU
Fri Oct 3 13:43:45 PDT 2008


On Oct 3, 2008, at 4:05 AM, emanu.storti at tiscali.it wrote:

> Thank you for your reply, I'm trying to get used to think in terms of
> Open World Assumption.
>
> I'm wondering if it is possible to "close" an
> instance, that is whether an instance can be constrained to have
> properties with a specific cardinality (I mean, at instance level,
> rather than at  class level).
> An example:
> m3 could be described with a
> datatype property maxNumberOfTask = "2": so it should have only 2 task
> connected (that is, the cardinality of "specifies" property must be
> exactly 2).
>
> It's different from saying that its class "specifies
> exactly 2 tasks", because I'd like to specify this from instance to
> instance.

You would do that by making the instance belong to a type with that  
restriction.  You can create an anonymous type for this purpose if you  
like.  That gives you the restriction at the instance level:

   m3  type  (specifies exactly 2)

> My class "Classification_Method" should be "the set of all
> instances that "specifies"  the task "classification" AND that have
> "specifies" property with a cardinality defined by the instances
> themselves, as the value of maxNumberOfTask.

Well, you can't use the value of a property as part of the restriction  
definition in OWL.  This was possible in the Loom language, using some  
of the first-order escape forms and also relying on closed world  
reasoning.  But in OWL, you can't do it.

> Classification_Method=
> (specifies_task HAS "classification") AND (specifies_task EXACTLY (the
> value of the property maxNumberOfTask, different from instance to
> instance))

This is not expressible using OWL.

>
>
> My question is: is it feasible to restrict a class using
> the value of its instances properties? It would mean that an instance
> must be semantically "self-coherent" to join that class (or, in other
> words, everything about that instance  has been said).

Well, that seems to rely on closed-world reasoning, which is also not  
supported in OWL.

> The last
> question is: I would like to define concept and relations using a
> formalism, in order to have a high level representation of the  
> ontology
> and also to describe it in my thesis with a human-readable syntax
> (unlike RDF/XML).
>
> Is there a standard logic language to do this? Maybe
> should I use DL standard representation?
> Where can I find any
> resources to learn how to use the syntax?

Well, there are various alternative syntaxes for OWL, such as the  
Manchester Syntax, Turtle Syntax, Compact OWL, etc.

Whether that will do what you want is an open question.






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