W3C home > Mailing lists > Public > public-owl-wg@w3.org > November 2007

Re: Punning and the "properties for classes" use case (from public-owl-dev)

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Sun, 4 Nov 2007 19:38:10 +0000
Message-Id: <0E6F2E3A-2A8E-4451-BF80-EFA20A6FEF76@comlab.ox.ac.uk>
Cc: Peter F. Patel-Schneider <pfps@research.bell-labs.com>, Jeremy Carroll <jjc@hpl.hp.com>, Michael Schneider <schneid@fzi.de>, public-owl-wg@w3.org
To: Alan Ruttenberg <alanruttenberg@gmail.com>

On 4 Nov 2007, at 04:35, Alan Ruttenberg wrote:

>
> I've moved the technical bit from this email to  http://www.w3.org/ 
> 2007/OWL/wiki/Compatibility_between_OWL_DL_and_OWL_Full
> as a starting point. Let's collect issues and evaluation metrics  
> there.
>
> (I'm still trying to understand the example)

It is possible in OWL to restrict the size of the domain to be 1 (or  
some other value) in all interpretations -- Peter uses the standard  
"spy point" trick to do this, by ensuring that every individual is  
related to the spy individual via the ex:s property and that the spy  
has at most one "incoming" ex:s edge (via a cardinality restriction  
in the inverse of ex:s).

Given such a restriction, it is obviously the case that sameAs (c d)  
is entailed for any two individuals c and d. In OWL Full sameAs (c d)  
additionally entails equivalentClass (c d), so we also get that  
Individual ( a type ( c ) ) entails individual ( a type ( d ) ).

We don't get this kind of entailment in OWL DL because classes are  
not interpreted in the same way as individuals (i.e., as elements of  
the domain), so for two classes c and d we would not necessarily  
entail equivalentClass (c d).

Hope this helps.

BTW, it seems to me that such an ontology must be inconsistent when  
interpreted with Full semantics because a would also be an instanced  
of Nothing, but this isn't relevant to the discussion.


>
> -Alan
>
>
> On Nov 2, 2007, at 1:20 PM, Peter F. Patel-Schneider wrote:
>
>> From: Alan Ruttenberg <alanruttenberg@gmail.com>
>> Subject: Re: Punning and the "properties for classes" use case  
>> (from public-owl-dev)
>> Date: Fri, 2 Nov 2007 13:01:00 -0400
>>
>>> On Nov 2, 2007, at 12:36 PM, Jeremy Carroll wrote:
>>
>> [...]
>>
>>> Also, I'd like to understand the reasoning behind Ian's assertion
>>>
>>>> Name separation is required, however, if Fast OWL is to be embedded
>>>> in RDFS in such a way as to be semantically compatible with  
>>>> Large OWL.
>>
>> This is precisely the argument that is being replayed right now.   
>> It was
>> thought that name separation would allow complete and exact
>> correspondence between the two semantics when ontologies were  
>> restricted
>> to OWL DL.
>>
>> This doesn't work because of domain size issues, e.g.,
>>
>> 	Axy x=y -> pa iff qa
>>
>> is "valid" in OWL Full but not in OWL DL.
>>
>> (Yes, this is neither OWL Full nor OWL DL, but it illustrates the  
>> point.
>> The OWL version is something like
>>
>> 	ObjectProperty ( ex:s inverseOf ( ex:si ) )
>> 	ObjectProperty ( ex:q )
>> 	SubClassOf ( owl:Thing restriction ( ex:s value ( ex:spy ) ) )
>> 	Individual ( ex:spy type ( restriction ( ex:si cardinality  
>> ( 1 ) ) ) )
>> 	Individual ( ex:a type ( ex:p ) )
>>
>> entails in OWL Full / does not entail in OWL DL
>>
>> 	Individual ( ex:a type ( ex:q ) )
>>
>> I leave it up to the WG members to rewrite this in RDF/XML.)
>>
>> I believe that the name separation compromise worked into the RDF
>> mapping was to try to achieve complete correspondence on the part  
>> of OWL
>> DL that was rewritable as RDF.  When it was shown that complete
>> correspondence was not possible name separation was already in and  
>> never
>> was revisited.
>>
>>>   (BTW, what's Fast OWL and Large OWL?)
>>
>> Working names for what became OWL DL and OWL Full.
>>
>>>
>>> -Alan
>>
>> peter
>
>
Received on Sunday, 4 November 2007 19:39:16 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:13:27 GMT