- From: Bernard Vatant <bernard.vatant@mondeca.com>
- Date: Thu, 10 Jan 2008 20:07:23 +0100
- To: Daniel Rubin <rubin@med.stanford.edu>
- Cc: Antoine Isaac <aisaac@few.vu.nl>, SKOS <public-esw-thes@w3.org>, SWD WG <public-swd-wg@w3.org>
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. 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? Best Bernard <http://mondeca.wordpress.com/>
Received on Thursday, 10 January 2008 19:07:43 UTC