Re: A problem with HasKey in the functional-style syntax

HI Boris,

just checking, to be sure:

- this does affect the RDF Mapping, but only in the func syntax side.
Ie, the RDF representation of HasKey does not change
- the grammar rules for OWL RL should also be updated but not the RDF Rules

Is that correct?

Ivan

Boris Motik wrote:
> Hello,
> 
> I'm sorry -- you are right; I misplaced the pipe symbol. It should have been
> like this:
> 
> HasKey := 'HasKey' '(' ClassExpression
>     [ 'ObjectPropertyList' '(' { ObjectPropertyExpression } ')' ]
>     [ 'DataPropertyList'   '(' { DataPropertyExpression   } ')' ]
> ')'
> 
> We should also add a restriction that there should be at least one (object or
> data) property.
> 
> This suggestion is motivated by the UML diagram. In fact, to get closer to UML,
> we could do this:
> 
> HasKey := 'HasKey' '(' ClassExpression
>     [ 'ObjectProperties' '(' { ObjectPropertyExpression } ')' ]
>     [ 'DataProperties'   '(' { DataPropertyExpression   } ')' ]
> ')'
> 
> I think I'd prefer not to repeat 'ObjectProperty' in front of each property. So
> unless anyone objects, I'd go with the latter suggestion.
> 
> Thanks again for catching this!
> 
> Regards,
> 
>  Boris
> 
>> -----Original Message-----
>> From: Michael Schneider [mailto:schneid@fzi.de]
>> Sent: 18 March 2009 20:36
>> To: Boris Motik
>> Cc: W3C OWL Working Group
>> Subject: RE: A problem with HasKey in the functional-style syntax
>>
>>> -----Original Message-----
>>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org]
>>> On Behalf Of Boris Motik
>>> Sent: Wednesday, March 18, 2009 6:37 PM
>>> To: 'W3C OWL Working Group'
>>> Subject: A problem with HasKey in the functional-style syntax
>>>
>>> Hello,
>>>
>>> I've just noticed a problem in the functional-style syntax for HasKey.
>>> The
>>> current syntax is
>>>
>>> HasKey( CE P1 ... Pn )
>>>
>>> where Pi are either object or data properties. But this means that the
>>> axiom is
>>> not fully typed. Consider, for example, the following axiom:
>>>
>>> HasKey( a:MyClass a:MyProperty )
>>>
>>> >From this axiom alone, it is not clear whether a:MyProperty is an
>>> object or a
>>> data property. Effectively, this means that we haven't addressed
>>> correctly the
>>> comment by Matthew Horridge.
>>>
>>> My proposal for fixing this is to write the above axiom like this:
>>>
>>> HasKey( a:MyClass ObjectPropertyList( a:MyProperty ) )
>>>
>>> More generally, the grammar would be like this:
>>>
>>> HasKey := 'HasKey' '(' ClassExpression
>>>    'ObjectPropertyList' '(' { ObjectPropertyExpression } ')' |
>>>    'DataPropertyList'   '(' { DataPropertyExpression   } ')'
>>> ')'
>> I don't understand this proposal. It seems to only cover the special cases,
>> where there are exclusively either object properties or data properties in
>> the argument list. What about mixtures of object and data properties?
>>
>> I first also wondered what this does buy us (or Matthew) at all, since this
>> doesn't make the HasKey axiom "typed". But I think what you mean is that the
>> declarations will be at least "local" to the axiom here, and won't be spread
>> around over the whole ontology, as it is currently the case. Is this right?
>>
>> Then, the obvious idea to me would be to generally allow for "inlined"
>> entity declarations, as in
>>
>>   HasKey ( Class(CE) ObjectProperty(P1) DataProperty(P2) ObjectProperty(P3)
>> DataProperty(P4) )
>>
>> One can allow this for every type of axiom, and make it mandatory in cases
>> such as for the properties in HasKey axioms.
>>
>> Yes, I know, yet another larger change. But is there an alternative? (Maybe
>> I totally miss the point here?)
>>
>> Best,
>> Michael
>>
>> --
>> Dipl.-Inform. Michael Schneider
>> Research Scientist, Dept. Information Process Engineering (IPE)
>> Tel  : +49-721-9654-726
>> Fax  : +49-721-9654-727
>> Email: michael.schneider@fzi.de
>> WWW  : http://www.fzi.de/michael.schneider
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> 
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
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