Re: http://ld2sd.deri.org/lod-ng-tutorial/

Hi Dan:
I think Alan already gave examples this morning. An ontology can contain 
statements about the relationship between conceptual elements - classes, 
properties, individuals - that (1) influence the result to queries but 
(2) are not likely retrieved when you just dereference an element from 
that ontology. The more complex an ontology is, the more difficult is it 
to properly modularize it.

But basically my main point is that the use of owl:imports is defined 
pretty well in

http://www.w3.org/TR/owl-ref/#imports-def

and there is no need to deviate from the spec just for the matter of gut 
feeling and annoyance about the past dominance of DL research in the 
field. And as the spec says - with a proper owl:imports statement, any 
application can decide if and what part of the imported ontologies are 
being included to the local model for the task at hand.

Martin


Dan Brickley wrote:
> On 22/6/09 23:16, Martin Hepp (UniBW) wrote:
>>
>>
>> Yves Raimond wrote:
>>>> Ontology modularization is
>>>> a pretty difficult task, and people use various heuristics for 
>>>> deciding what
>>>> to put in the subset being served for an element. There is no 
>>>> guarantee that
>>>> the fragment you get contains everything that you need.
>
>> There is no safe way of importing only parts of an ontology, unless you
>> know that its modularization is 100% reliable.
>> Serving fragments of likely relevant parts of an ontology for reducing
>> the network overhead is not the same as proper modularization of the
>> ontology.
>
> Can you give a concrete example of the danger described here? ie. the 
> pair of a complete ("safe") ontology file and a non-safe subset, and 
> an explanation of the problems caused.
>
> I can understand "there is no guarantee that the fragment you get 
> contains everything you need", and I also remind everyone that 
> dereferencing is a privilege not a right: sometimes the network won't 
> give you what you want, when you want it. But I've yet to hear of 
> anyone who has suffered due to term-oriented ontology fragment 
> downloads. I guess medical ontologies would be the natural place for 
> horror stories?
>
> cheers,
>
> Dan
>
>

-- 
--------------------------------------------------------------
martin hepp
e-business & web science research group
universitaet der bundeswehr muenchen

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