Re: Issue-114

On Jun 30, 2008, at 9:26 PM, Alan Ruttenberg wrote:

> On Jun 30, 2008, at 2:46 PM, Rinke Hoekstra wrote:
>
>> Hi Alan, Michael,
>>
>> On 30 jun 2008, at 19:59, Alan Ruttenberg wrote:
>>> After discussion with Michael, we agreed to narrow this issue as  
>>> follows: We propose that the only punning in OWL is against  
>>> individuals - that is, anything named in OWL can have an  
>>> individual with the same (punned name).
>>
>> Could you please clarify what the underlying reason is for this  
>> restriction? Object/datatype property punning and class/datatype  
>> punning were problems because of a compatibility issue with OWL  
>> Full. Is there a similar problem with class/property and  
>> individual/property punning?
>
> There is no problem with individual/property punning - this is  
> included as valid in my proposal. There has never been, as far as I  
> am aware, a call for class/property punning.

Sure there has.

	1) To handle more RDF graphs. (class/property punning is in OWL  
Full, with exactly the same semantics.)
	2) To handle various integration/alignment situations.

Furthermore, these are already in and in OWL2 implementations.

>> If the restriction is based on an apparent lack of use cases I'm  
>> sure with a little effort we could come up with several. For  
>> instance,
>>
>> 1) The use of elephant and mouse properties to represent 'all  
>> elephants are bigger than all mice' (Markus' paper). The trick is  
>> to bridge the gap between TBox and RBox by making e.g. the class  
>> 'elephant' equivalent to a self restriction on the 'elephant'  
>> property. Role inclusion axioms can then be used (together with  
>> the universal role) to connect all elephants to all mice. I feel  
>> that this is a case where class/property punning is appropriate.
>
> In the case of individual/xx punning, we have the prospect (in DL)   
> of (eventually)  saying x (individual) sameAs y  (individual) => x  
> (type specific equivalence) y, In OWL full this is already part of  
> the semantics.
>
> How should this work with punning between properties and classes?

The same (effectively) as in OWL Full, i.e., punning.

>>  Having just class/individual punning is hard to defend (in  
>> particular because, at least in my view, most cases for class/ 
>> individual punning is just bad practice)
>
> It may be bad practice, but is is requested. To the extent that we  
> are chartered to provide features that have been identified by  
> users as widely needed,

Actually, I don't see that we're chartered to do that:

"""The mission of the OWL Working Group, part of the Semantic Web  
Activity, is to produce a W3C Recommendation that refines and extends  
OWL. The proposed extensions are a small set that:"""

I do think it's a good idea though.

> I think it ought to be a consideration in choosing what is in and  
> outside OWL. If we don't get rich annotations, the class and  
> property to instance punning will provide features that can not  
> otherwise be met.

The starting point is OWL 1.1. I think we should deviate from  
included features that have been interoperably implemented only when  
there are clear and strong arguments against them.

Cheers,
Bijan.