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Re: SKOS Reference Editor's Draft 23 December 2007

From: Dan Brickley <danbri@danbri.org>
Date: Wed, 09 Jan 2008 11:52:00 +0000
Message-ID: <4784B560.1030605@danbri.org>
To: Simon Spero <ses@unc.edu>
CC: "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>, SKOS <public-esw-thes@w3.org>

ref: http://www.w3.org/2006/07/SWD/SKOS/reference/20071223#L2413

Simon Spero wrote:
> [Greetings from Sunny Chigwell]

And from sun-kissed Bristol...

> I'm still really, really uncomfortable with the breakage of  
> skos:broader, primarily in regards to the loss of transitivity.

Me too. I feel a bit guilty, I saw these threads go past but didn't
really get that transitivity was being dropped. I think this is a
probably a mistake. The transitivity of skos:broader comes from the "er"
part in the naming, ... something is more something than something else.
More broad, in this case. Younger, richer, broader, ... etc.

> BT relationships in all compliant thesauri must be transitive. 
> 
>   Each of the relationships should lead to hierarchies that are amenable 
> to a logical test through reference to the basic types of concept 
> represented by the terms. (NISO 2005, §8.3)
>  
> As an  example of a valid hierarchical relationship and test  (NISO 
> 2005, Figure 6 ) uses:
> 
> /cacti/   ∝ /succulent plants /
> SOME /succulent plants/ are /cacti/
> ALL /cacti/ are /succulent plants/
> /
> /The example given for an  invalid hierarchical relationship is (NISO 
> 2005, Figure 7 )
> 
> /cacti/ ∝ /desert plants /
> SOME /desert plants/ are /cacti/
> SOME /cacti/ are /desert plants

SKOS is by design more scruffy than RDFS/OWL class hierachies, so saying

_:cacti:concept skos:broader _:desert_plant  isn't quite like saying
"there's a class Cacti that is subClassOf DesertPlant, and anything in
te former is in the latter". With SKOS, it's more like, here's a couple
of concepts, and then we attach semantics like "anything that is a
document that is about the former is also in a sense about the latter".
With the wiggle-room expressed in supporting vocabulary, eg.
skos:subject. So we could agree that c1 has skos:broader c2, yet have
plenty of room to debate about what else that implies, if anything.


> A  relationship that does not obey these properties is not hierarchical 
> and should not be labeled as such. 

Yep, it's perfectly OK to be able to write false claims in SKOS. There's
nothing wrong with being wrong.

		 The relationship is associative, and
> can be modeled in SKOS using the appropriate construct 
> (skos:related).    The error is in the data, not the standard.

+1

cheers,

Dan
Received on Wednesday, 9 January 2008 11:52:14 GMT

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