- From: Daniel Rubin <rubin@med.stanford.edu>
- Date: Sat, 12 Jan 2008 05:58:28 -0800
- To: Bernard Vatant <bernard.vatant@mondeca.com>
- Cc: Antoine Isaac <aisaac@few.vu.nl>,SKOS <public-esw-thes@w3.org>, SWD WG <public-swd-wg@w3.org>
At 11:07 AM 1/10/2008, Bernard Vatant wrote: >OK Daniel, let me have another try if you don't mind :-) >> >> From my point of view, it does NOT make sense that skos:narrower >> and broader are not transitive. >>And if applications can go ahead and make them transitive by >>expanding how they wish, that violates the asserted SKOS semantics. >>Unless I'm misunderstanding something here, this sounds like a >>formula for chaos. >Expanding the query does not *make* the relation transitive, it's >just an application feature. I don't see any violation of the >semantics. The results proposed are not results of the original >query, but from *query expansion*. The query expansion is not the >original query, right? There is one single way to strictly answer >the query, and many ways to expand it. > >I have this real-life example at a customer's in legal publication. >The figures are around 2 million documents, and 50,000 concepts in >the vocabulary (and growing), with a very deep tree. >Suppose I start a search at level 3, on a concept with 5 direct >narrower concepts, and about 500 more downwards if transitivity is applied. >If I don't expand the query, say I get 40 answers indexed on the >direct narrower concepts, if I expand it with unbound transitivity, >say I get 4,000 answers. Way too many. Think about performance. My point is that the relation semantics should determine whether it is appropriate to expand a term transitively. I got the sense from prior discussion that people were talking about doing that regardless of transitivity. > From a end-user perspective, what is the best? Retrieving very > quickly the 40 resources classified directly by the 5 direct > children, and allowing the user to expand from one of those one or > two steps down, does not seem a recipe for chaos, but for a sound > adaptation to the context, and for tackling some scalability > issues. If transitivity is built in the semantics, I have to go > down the tree and retrieve the 4,000 answers. If I want to trim the > tree to limit the results, there I will break the semantics ... > >Does that make sense? How many levels an application decides to expand is independent of whether it is semantically correct to expand along that relation in the first place. >Best > >Bernard > > ><http://mondeca.wordpress.com/> >
Received on Saturday, 12 January 2008 13:58:41 UTC