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

From: Michael Hausenblas <michael.hausenblas@deri.org>
Date: Tue, 23 Jun 2009 09:20:02 +0100
To: <martin.hepp@ebusiness-unibw.org>
CC: <mark.birbeck@webbackplane.com>, "Booth, David (HP Software - Boston)" <dbooth@hp.com>, Linked Data community <public-lod@w3.org>
Message-ID: <C6664EC2.5D47%michael.hausenblas@deri.org>

Martin,

> (moving this to LOD public as suggested)

Thanks.

> 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.

I don't think it is particular helpful to insult people, to utter
imputations and judge a book by its cover. If we can agree to stop using
such terminology I'm more than happy to continue the discussion.

> 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.

Ok, so, again, for the chaps who didn't get the entire story. Martin
champions the use of owl:import (and wants to see it written down as a good
practice?) in linked data.

My take on this is as follows: when one takes the linked data principles and
applies them in practice (esp. referring to #2, here) there are naturally a
dozens implementation choices as the principles simply leave room for
interpretation. 

The people here know me from the RDFa TF, from the AWWSW TF and last but not
least from the LOD community as a simple-minded, pragmatic guy, I hope ;)

So, my hunch would be: the market will make the final decision, not a Martin
Hepp and also not a Michael Hausenblas. If people think this is a clever
idea, they will use it when publishing linked data. AFAIK, to date the usage
of owl:import in linked data is close to non-existing (even in pre-LOD times
it seemed to be not very common [1]).

Concluding, I'd propose - respecting the nature of good *practice* - once we
notice a serious usage of owl:import in LOD data, we may want to rehash this
topic.

Cheers,
      Michael

[1] http://ebiquity.umbc.edu/blogger/2007/06/15/how-owlimport-is-used/

-- 
Dr. Michael Hausenblas
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730
http://linkeddata.deri.ie/
http://sw-app.org/about.html



> From: "Martin Hepp (UniBW)" <martin.hepp@ebusiness-unibw.org>
> Organization: http://www.heppnetz.de
> Reply-To: <martin.hepp@ebusiness-unibw.org>
> Date: Mon, 22 Jun 2009 20:42:23 +0200
> To: Michael Hausenblas <michael.hausenblas@deri.org>
> Cc: <hepp@ebusiness-unibw.org>, Richard Cyganiak <richard@cyganiak.de>, "Hepp,
> Martin" <mhepp@computer.org>, Hugh Glaser <hg@ecs.soton.ac.uk>,
> <mark.birbeck@webbackplane.com>, "Booth, David (HP Software - Boston)"
> <dbooth@hp.com>, Linked Data community <public-lod@w3.org>
> Subject: 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
> 
> 
> 
> 
Received on Tuesday, 23 June 2009 08:20:42 UTC

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