[topicmapmail] XTM-RDF conversion

[Dicheva, Darina]

Lars Marius and Knud, your feedback is appreciated!

Thanks,
Darina  

> -----Original Message-----
> From: topicmapmail-bounces at infoloom.com 
> [mailto:topicmapmail-bounces at infoloom.com] On Behalf Of 
> Dichev, Christo
> Sent: Monday, June 11, 2007 4:42 PM
> To: Lars Marius Garshol; topicmapmail at infoloom.com
> Cc: Boriana Ditcheva
> Subject: RE: [topicmapmail] XTM-RDF conversion
> 
> Hi,
> 
> In our implementation we are using/creating  vocabulary based on the
> namespace  http://www.w3.org/2006/rdftm/ taken from the 
> :Guidelines for
> RDF/Topic Maps Interoperability"
> (http://www.w3.org/2001/sw/BestPractices/RDFTM/guidelines-2006
> 0630.html)
> . Our initial experiments indicate that this site is not maintained
> anymore - it generates "Not Found" error. 
> 
> Your advice or suggestions on this matter will be appreciated.
> 
> Christo 
> 
> -----Original Message-----
> From: topicmapmail-bounces at infoloom.com
> [mailto:topicmapmail-bounces at infoloom.com] On Behalf Of Lars Marius
> Garshol
> Sent: Monday, June 11, 2007 3:13 AM
> To: topicmapmail at infoloom.com
> Cc: Boriana Ditcheva
> Subject: Re: [topicmapmail] XTM-RDF conversion
> 
> Hi Darina,
> 
> * Dicheva, Darina
> >
> > We are currently implementing an XTM-RDF conversion for 
> TM4L. In this 
> > relation, I would like to ask for an opinion on translating  TM 
> > associations.
> 
> This problem is in my opinion already solved. An algorithm for such
> conversion is given at
> 
>    http://www.ontopia.net/topicmaps/materials/tmrdf.html#N1024
> 
> and is implemented in the OKS Samplers, so you can try it out for
> yourself. (Just use "Export" and select RDF/XML.)
> 
> A set of PSIs that can be used to guide the conversion are defined at
>    http://psi.ontopia.net/tm2rdf/
> 
> > The problem is that RDF is built on directional binary relations:
> > Subject-Property-Object, while in TM a binary association  
> authorship 
> > has five elements:
> >
> > authorship(author: Shakespeare, work: Hamlet).
> 
> The natural translation of this in RDF is in my opinion:
> 
>    has-author(hamlet, shakespeare)
> 
> The roles are just an artifact of how the information is expressed in
> Topic Maps, and are not needed in RDF.
> 
> > Currently we are thinking of translating such an association as
> >
> > 	Author -- wrote -- Work
> >
> > but are wondering whether to include also the reverse part of the 
> > relationship in the translation:
> >
> > 	Work -- written-by -- Author
> >
> > How would including it, or not including it, affect RDF 
> > completeness/readability/inference capability?
> 
> You don't need to include it, since the question of what the 
> inverse is
> is one that exists for every RDF statement. OWL lets you 
> handle this (if
> you want) by explicitly stating that one property is the inverse of
> another, as in
> 
>    wrote owl:inverseOf written-by
> 
> > Clearly, if we want to represent both directions, we'd have to make 
> > two statements per every association instance: [...]
> 
> Actually, if you use owl:inverseOf then software can infer the inverse
> statements. Not all software does, but in theory it could, and in
> practice it often does.
> 
> > Would that be undesirable?
> 
> I think so, yes. It's better to just state it once.
> 
> > There are, of course, other more thorny issues related to scope and 
> > variants, but piece-by-piece.
> 
> Yes. Scope and variants is harder. :)
> 
> --Lars M.
> 
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