Re: OWL class restriction

Hi Alessandro,

On 13 Jan 2010, at 11:09, Alessandro Maccagnan wrote:

> Hi Uli,
>
> thanks for your reply.
> We are trying to define a propertyChain but we realize that what we  
> need to say is as follows.
>
> defining these properties:
>    Action has_object Some Object
>    Action has_action_goal Some Goal
>    Object has_object_goal Some Goal
>
> at the individuals level we would like to say:
>
> a1 has_action_goal g1
> o1 has_object_goal g1
> o2 has_object_goal g2
> =>
> a1 CAN HAVE has_object o1
>
> BUT
> a1 CANNOT HAVE has_object o2
>
> So this means that only the objects (o) that have the same goal (g)  
> of the
> action (a) can be used in that action.

I don't think that this can be said in OWL because you will have to  
say that every individual x that is related to an individual y via  
has_object must also have another link to y via the chain  
has_action_goal o inverse(has_object_goal). This statement requires  
three variables in first-order logic, hence it's unlikely that it can  
be expressed in OWL. (Or does anyone here see a clever trick?) You  
might be more lucky with a rule language, but that is not my domain.

Second, together with the rule you stated in your last sentence, the  
ontology you gave is not sufficient to conclude that a1 cannot have o2  
as an object: the individuals g1 and g2 can be the same, and actions  
and objects are not prevented from having other goals than the ones  
stated. You will at least have to make all individuals different and  
close the "some" restrictions with corresponding "only" restrictions.  
Even then, the open world assumption might play a trick on you in the  
cases where you haven't said anything about certain individuals, so  
you might require closed world reasoning here.

Cheers

Thomas

> Any suggestions?
>
> Cheers
> Alessandro
>
> On Tue, Jan 12, 2010 at 5:51 PM, Uli Sattler <sattler@cs.man.ac.uk>  
> wrote:
> Hi Alessandro,
>
> this is a tricky think to be done. What you can do is use a  
> propertychain to ensure that
>
> the composition of  has_object with has_Goal implies has_Goal.
>
> This would require the usage of a dedicated 'has_Goal' (rather than  
> a less specific has_information) property, but this shouldn't be a  
> problem (make has_information a superproperty of has_Goal if you  
> like).
>
> Does this suffice? Cheers, Uli
>
>
> On 12 Jan 2010, at 14:54, Alessandro Maccagnan wrote:
>
> Hello,
>
> we are developing an ontology for the description of a general  
> Action structure. The Action Structure is composed of:
>
> Subject (that performs the action)
> Object_complement (that undergoes the action)
> Complement (that helps in the execution of the action)
> Goal of Action (the effect of the action)
>
> We have already defined that:
>
> Action has_information one Goal_of_action
> Action has_object some Object
> Object is_object_in some Action
> Object has_information some Goal_of_action (because an object can be  
> used in several distinct actions)
>
> Now we would like to say that an Action can have as its objects only  
> those that have the same goal of the related action.
>
> Action has_object some Object where Object.Goal=Action.Goal
>
> Unfortunately we are stuck because we do not know how to formalize  
> it in OWL. Does anybody have any suggestions to help us?
>
>
> Kind regards,
>
> Alessandro Maccagnan
>
>
>
>
>
>
> -- 
> Alessandro
> Maccagnan

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