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RE: What is needed to move forward

From: Evain, Jean-Pierre <evain@ebu.ch>
Date: Mon, 9 Feb 2009 16:50:41 +0100
Message-ID: <14AE8514098875488F9FEACD90C747A227772A@gnvasmail1a.gva.ebu.ch>
To: Raphaël Troncy <Raphael.Troncy@cwi.nl>, "Felix Sasaki" <fsasaki@w3.org>
Cc: "Pierre-Antoine Champin" <pchampin@liris.cnrs.fr>, <public-media-annotation@w3.org>
(in other words, I think it would be useful to address such questions when
developing a solution as we are not writing it for ourselves but for
potential users)

Dear Raphael,

Thanks for answering my questions for which I had most of the answers ;-) 

However, I'd like to know more about the ESW wiki. Maybe obvious but.. Can
you tell me more?

Thanks in advance.


-----Original Message-----
From: public-media-annotation-request@w3.org
[mailto:public-media-annotation-request@w3.org] On Behalf Of Raphaël Troncy
Sent: lundi, 9. février 2009 16:41
To: Felix Sasaki
Cc: Pierre-Antoine Champin; public-media-annotation@w3.org
Subject: Re: What is needed to move forward

Dear All,

>> But I do think that, without such a formal framework for defining our
>> ontology,
>> we will fail to "help developers with the lack of syntactic and semantic
>> interoperability" (from the charter).
> Here I fundamentally disagree. I think that deliverable from the
> metadata working grop
> http://www.metadataworkinggroup.org/pdf/mwg_guidance.pdf

Hum, I think all this discussion, though very interesting, crystalized 
on very polysemic terms that actually are not relevant. I meant formal 
vs non formal, we can argue for hours what are their boundaries and it 
will not solve our problem.

Felix, there is nothing less or more formal in the work from the 
metadata working group that what PA is proposing, so there is no need to 
oppose these views. Thinking more about the SWCG telecon last Friday, I 
think there are also some misunderstandings from what the SW side of 
this group (if any) is proposing. Let me clarify ...

It seems to me that the basic problems we have, is that we have a great 
table containing mappings between various formats. What do these 
mappings mean? Sometimes that property A is the same than property B. 
Sometimes that A is a bit more specific than B. Sometimes that A has 
nothing to do with B (disjoint). Sometimes that A is somehow related to 
B but we cannot really further detail this relationship ... Is there 
something else?

Your prose description will say exactly that, right? PA and others 
argue, I think, that all these sentences could be exactly encoded using 
the RDF model (and it sublanguages) and could perfectly reflect exactly 
the same level of fuzzyness in the meaning of the association between A 
and B (e.g. skos:related is just a skos:semanticRelation !)

All these statements could be made in the MAWG ontology. It will not 
change of one iota the semantic commitment of any of all these 
standards, but it will provide great interoperability. What is your 
specific concern with this approach?

Regarding Jean Pierre questions:

> [
> - what is the role of structured XML schemas (what do they do that e.g.
> RDF/OWL doesn't or maybe less adequately like cardinality and type or ID
> management)

XML Schema defines types, that have as unique goal to be re-used. You 
can re-use previously defined types in complete different context in XML 
Schema, since they provide convenient bag of XML elements put together. 
MPEG-7 uses this feature a lot. As a result, you have the same type used 
in two very different meanings, resulting in interoperability problems 
at the processing level.

OWL/RDF defines the semantic meaning of the objects. You will not use 
the same concept simply because they happen to have similar properties.

> - if I go for an RDF/OWL model, what is its role? How different is it from
> dumb RDF description (why is it NOT rdfising existing XML schemas? What
> makes its value and who will integrate it to exploit metadata instances
> (what would search engines do with it)?

You can rdfising XML Schemas. But doing so, you will necessary based 
this transformation on an implicit OWL/RDFS/SKOS model. So why not 
having it explicit?

> - How do I generate instances? From where (transformation from structured
> metadata instances or from a database)? What are the tools to generate
> templates from complex models?

There are plenty. The ESW wiki is a good start.
The triplify method, conference series, tools and tutorials are also 
valuable resource.
W3C might launch a RDB2RDF WG after the XG of the same name.

> Which conclude with the statement "Quite a lot of work to be done", for
> the formalization. I very much doubt that it is worth the effort, if
> nobody comes up with a simple example to demonstrate its value.

I don't see the effort ... Write the prose, it can be translated in RDF 
in a few min.

I will rather reverse the problem. If the RDF cannot be written in a few 
minutes, it means that there is serious misinterpretation possible from 
your prose description. My conclusion will be that you will not have 
solve the interoperability problem, but perhaps making it worse, adding 
another vocabulary ...

> I would rather like to spend time on what Jean-Pierre proposed:
> "I would therefore suggest that we dedicate part of the next physical
> meeting
> going through these issues asking everyone of us to come with a
> presentation. "


Best regards.


Raphaël Troncy
CWI (Centre for Mathematics and Computer Science),
Science Park 123, 1098 XG Amsterdam, The Netherlands
e-mail: raphael.troncy@cwi.nl & raphael.troncy@gmail.com
Tel: +31 (0)20 - 592 4093
Fax: +31 (0)20 - 592 4312
Web: http://www.cwi.nl/~troncy/

Received on Monday, 9 February 2009 15:51:48 UTC

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