Broader and narrower in Vocab

Broader / narrower (b/n) might be said to simply be an indicator of the direction of a relationship between two terms; it does not define the relationship type. So the b/n relationship cosmology / cosmicBackground is that of a 'subject area includes topic' relationship, Galaxy / seyfertGalaxy is a 'type includes subtypes' relationship, and solarSystem / planet is a 'has component or part' relationship.  

It would seem that a solution to the b/n conflict would be to allow a concept to belong to more than one broader concept, but this is not, AFAIK, possible in SKOS. I suspect we have to choose one of the following options:  

1. Accept that we must have many-to-many b/n relationships and so cannot use SKOS to record the IVOA vocabularies: use some sort of ontology format (OWL?).
2. Accept the above but use SKOS to record the concepts and decide (majority vote?) to place each concept under the parent concept people would be most likely to search on. [2a. Perhaps as a parallel activity (if someone wants to undertake it), an ontology is created whereby each term in the ontology is the URI of each SKOS concept and all the relationships are recorded. This would enable both simple (SKOS-based) and complex (ontology-based) search engines to be trialled.]
3. Accept that it would take too long to agree on which type to use for each b/n relationship and only define the concepts in the SKOS-based IVOA vocabulary.

Comments?  

Cheers,
Tony.  

-- 
Tony Linde
Phone:  +44 (0)116 223 1292    Mobile: +44 (0)785 298 8840
Email:  Tony.Linde-at-leicester.ac.uk
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Project Manager, EuroVO VOTech   http://eurovotech.org 
Programme Manager, AstroGrid     http://www.astrogrid.org 
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