Re: Astounding silence about same-ness Re: Concept Equivalence, IFPs, skos:subjectIndicator and owl:sameAs

Hi Mikael

Thanks for breaking the silence :-)
>> There again, this story points to a current lack of expressiveness in 
>> the whole RDF-OWL-SKOS toolkit, forbidding to say properly : Those two 
>> things/concepts/resources describe the same thing, yes, but, er, well, 
>> not really in the sense of owl:sameAs.
>>     
> Well, couldn't this be a case of "we're describing the same thing, BUT
> we're using different descriptions" ?
>   
Agreed, if "different descriptions" means different formal 
conceptualizations, IOW different resources. I had already met a strong 
disagreement from some folks on the fact that an RDF resource *is a 
description* in that sense. Not to confuse with rdf:Description, which 
is actually a bag of elements for this description of the thing. We have 
to tackle some way this level of indirection.
> It seems to me that skos:Concept is an *explicit* conceptualization of
> some thing. With a history, purpose, etc in itself, separately from the
> thing.
>   
Agreed. So you need this level of indirection between the thing and the 
resource which describes it.
> so by using owl:sameAs, we're saying that not only are the described
> "things" the same, but we're also using the *same* conceptualization,
> with the same history etc.
>   
Absolutely. So the two descriptions/resources are merged, and that's not 
what we want.
> OTOH, it's certainly an interesting statement to say, well, we're
> talking about the same thing (subjectIndicator) but we're using
> different conceptualizations, etc.
>   
Certainly. But the point of Stuart is that if subjectIndicator is an 
IFP, the logical result is the same (sorry) as if you use directly 
owl:sameAs
> So, in short, couldn't the answer be that we are really talking about
> two resources - the thing and the conceptualization?
>   
ABSOLUTELY! I'm happy you come to this conclusion at the end of this 
kind of Socratic dialogue. Now all my point with "hubjects" or "blank 
subjects" is that the resource which is the thing is beyond any 
description - otherwise you get into a recursivity loop. And subject 
indicator is not a killer solution to that, as I discovered after 
passing years munching this notion in OASIS Technical Committtee. The 
subject indicator is yet another conceptualization for the thing (less 
formal, more for humans, but the issue remains the same).

That's why I suggest this thing beyond the 
conceptualizations/descriptions to be pointed as a really blank node, 
using whatever relevant pointer. I have discussed this with Tom Baker 
who did not see any formal opposition to use dc:subject here, but it's a 
quite weird use of it. I think we really need a specific property, and 
of course NOT an IFP.
And I would be happy to have it in skos namespace, something like     
skos:isConceptFor, so we would have

a:thisConcept      skos:isConceptFor      _:thingFoo
b:thatConcept      skos:isConceptFor      _:thingFoo

The _:thingFoo balnk node having no other purpose that linking the two 
concepts without merging them, and of course no rdf:Description whatsoever.

Well, I think I've hit that nail more than enough for now.

-- 

*Bernard Vatant
*Knowledge Engineering
----------------------------------------------------
*Mondeca**
*3, cité Nollez 75018 Paris France
Web:    www.mondeca.com <http://www.mondeca.com>
----------------------------------------------------
Tel:       +33 (0) 871 488 459
Mail:     bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com>
Blog:    Leçons de Choses <http://mondeca.wordpress.com/>

Received on Tuesday, 7 November 2006 11:07:59 UTC