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

Hi Michael:

(moving this to LOD public as suggested)

General note: I am quite unhappy with a general movement in parts of the 
LOD community to clash with the OWL world even when that is absolutely 
unnecessary. It is just a bad engineering practice to break with 
existing standards unless you can justify the side-effects. And this 
stubborn "i don't care what the OWL specs says" pattern is silly, in 
particular if the real motivation of many proponents of this approach is 
that they don't want or cannot read the OWL specs.

As for owl:imports:

When importing an ontology by owl:imports, you commit to the whole 
formal account of that ontology. If you just include an element from 
that ontology by using it and hope that dereferencing will get the 
relevant formal account in your model, you expose your model to 
randomness - you don't know what subset of the formal account you will 
get served. 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.

On the other hand - what is your pain with  using RDFa in a way so that 
the extracted RDF model is equivalent to the model from an RDF/XML or N3 
serialization? Why this absolutely arbitrary "we LOD guys don't like 
owl:import ( we don't like OWL anyway, you know?), so we simply omit it" 
behavior?

It is just silly to break with established standards just for saving 1 - 
2 triples.

Best
Martin

Michael Hausenblas wrote:
> Martin, 
>
> As an aside: I think I proposed already once to not have this discussion in
> a private circle of 'randomly' selected people but rather in the appropriate
> lists (rdfa public or public-lod). However, if you prefer to continue here,
> we continue here, FWIW.
>
>   
>>> In my opinion the owl:imports
>>> stems from a time where people confused publishing on the Semantic Web with
>>> firing up Protege and clicking around like wild. So, concluding, for me it
>>> is not obvious to use owl:imports and I don't see *any* benefit from using
>>> it. Not in RDF/XML and also not in RDFa ;)
>>>       
>> you know that i sometimes appreciate your opinion ;-),
>>     
>
> Yeah, same here :D
>
>   
>> ... but i think it is
>> pretty questionable to break with well-defined standards specifications
>> for just a matter of gut feeling and personal preference.
>>     
>
> Ok, let me rephrase this. You, or whoever publishes RDFa can of course do
> whatever she likes. Wanna use owl:imports? Fine. Don't wanna use it. Ok!
>
> The point I was trying to make (not very successfully, though): from a
> linked data perspective (and basically this is what Richard and I try to
> achieve here; offering good practices for linked data *in* RDFa) the usage
> of owl:imports is, how to put it, not encouraged.
>
> So far I have not heard any convincing argument from you why one should use
> it, but I'm happy and open to learn.
>
> Cheers,
>       Michael
>
>   

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

e-mail:  mhepp@computer.org
phone:   +49-(0)89-6004-4217
fax:     +49-(0)89-6004-4620
www:     http://www.unibw.de/ebusiness/ (group)
         http://www.heppnetz.de/ (personal)
skype:   mfhepp 
twitter: mfhepp

Check out the GoodRelations vocabulary for E-Commerce on the Web of Data!
========================================================================

Webcast:
http://www.heppnetz.de/projects/goodrelations/webcast/

Talk at the Semantic Technology Conference 2009: 
"Semantic Web-based E-Commerce: The GoodRelations Ontology"
http://tinyurl.com/semtech-hepp

Tool for registering your business:
http://www.ebusiness-unibw.org/tools/goodrelations-annotator/

Overview article on Semantic Universe:
http://tinyurl.com/goodrelations-universe

Project page and resources for developers:
http://purl.org/goodrelations/

Tutorial materials:
Tutorial at ESWC 2009: The Web of Data for E-Commerce in One Day: A Hands-on Introduction to the GoodRelations Ontology, RDFa, and Yahoo! SearchMonkey

http://www.ebusiness-unibw.org/wiki/GoodRelations_Tutorial_ESWC2009