W3C home > Mailing lists > Public > public-esw-thes@w3.org > January 2008

Re: [SKOS] The return of ISSUE-44 (was Re: TR : SKOS Reference Editor's Draft 23 December 2007)

From: Daniel Rubin <rubin@med.stanford.edu>
Date: Sat, 12 Jan 2008 05:58:28 -0800
Message-Id: <>
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.

Received on Saturday, 12 January 2008 13:58:43 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:14:56 UTC