Re: SKOS and Rules

Hi Sean,

You pointed at a very important problem here

>
>
> The SKOS Core Guide includes reference to rules:
>
> http://www.w3.org/TR/swbp-skos-core-guide/#secaboutrules
>
> [[
> Inference rules are part of SKOS Core. Inference rules are
> described in prose, and where appropriate are expressed using the Jena
> 2 rule syntax [Jena Inference], or as RDF statements using the OWL
> vocabulary [OWL]. Inference rules appear in boxes such as:
>
> An example rule.
>
> (?x ex:p ?y)
> ->
> (?x ex:q ?y)
>
> prefix ex: <http://www.example.com/eg#>
>
> ]]
>
> I can see what's going on here, but it makes me a little
> uncomfortable. If the SKOS recommendation is to make use of additional
> infrastructure, shouldn't this be couched in terms of a standards
> (e.g. RIF when it appears) rather than referring to some particular
> implementation (Jena rules)?

I completely agree with you. But I think that at the time when these 
rules where specified standards where not easily available, nor really 
helpful to get a simple message get through (RuleML/SWRL?)

>
> Is there going to be some notion of comformance? For example, does
> this mean that I *cannot* provide a SKOS implementation without having
> some RDF repository that implements the rules -- and in that vein,
> what are the precise intended semantics of these rules?

Alistair would perhaps be better placed than me to answer. However, I 
have worked with SKOS for quite a while now, and to me it is now quite 
natural to consider that the rules are part of the spec, and therefore 
should be implemented if one wants to implement a proper SKOS engine. 
This explain perhaps there have been cases of vocabularies represented 
using SKOS, but no "official" SKOS inference engine... (though such a 
thing wouldn't be too hard to implement, I suppose)
Concerning the semantics of the rules, well I suppose that the idea was 
just to have some production rule that would enable to specify formal 
inferences fitting what the SKOS model was trying to render. And I 
supposed that if OWL had offered means to represent general relational 
composition, there wouldn't have been such Jena-like axioms, but just 
OWL ones, as for e.g. the transitivity of skos:broader.

Whatever be the case, it is clear that this should be clarified for 
further version of SKOS. Notice by the way that some of the concerned 
axioms (either OWL ones or "rules") are quite controversial (well, I 
disagree with the relevance of some, and am not the only one), and might 
disappear from a further version of SKOS.

Cheers,

Antoine

Received on Monday, 27 November 2006 23:04:44 UTC