On Mittwoch, 16. April 2008, Aerik Sylvan wrote:

S Page wrote:

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Aerik Sylvan wrote:

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At the risk of asking a stupid question: what is the status of category intersections?

At the risk of making a stupid answer: you could install the Semantic MediaWiki extension and make queries like

{{#ask: [[Category:Actor]] [[Category:Director]] }}

SMW will query for membership of subcategories (thus it'll match members of Child actors) , to a configurable depth limit. The nifty thing is you can display other properties and categories of matching pages.

See demo (temporarily) at, http://www.semanticweb.org/wiki/Sandbox#Category_intersections

That's cool... what's the backend for that? (I looked briefly at some docs at http://semantic-mediawiki.org/wiki/Semantic_MediaWiki but didn't quickly find any architecture stuff).

Better late than never: the intersections currently are computed with straightforward SQL calls using joins. Before that, the query that a user enters is parsed and pre-processed (e.g. to limit the complexity of the query). It would be nice if we could have some faster backend for category intersections, e.g. using column-based DBs or fast RDF-stores instead of MySQL. Changing the storage backend in SMW can be done in a very modular fashion, since all concrete methods for accessing SQL are in one file -- the rest of the system uses interface methods instead of direct SQL calls.

Cheers

Markus

Best Regards, Aerik