RE: Concept Equivalence, IFPs, skos:subjectIndicator and owl:sameAs (was Re: SKOS Guide and owl:sameAs)

Hello Bernard,

> How's that?

Basically fine, but I think that there is an aspect of the original question [1] that's got lost.

	"Is there a *reason* why concept equivalences established via 
	the skos:subjectIndicator are "good" and equivalencies established 
	via owl:sameAs are bad?" [added emphasis]

At the risk of blowing a 3 sentence limit, I think that there is a danger (at least on my part) of zooming in on mechanisms and problem solving without necessarily understanding the original motivation/use-cases that informed the design. I think the question that I asked was a question about design intentions.

There seems to be a tension between a desire to maintain an distinction between independent conceptualisations of similar (identical?) subjects and at the same time to indicate the similarity (equivalence?) of the thing that they are conceptualisations of. I'm not from the thesaurus community and don't have an intrinsic understanding of the requirements that drove the design. It seems to me that revisiting those might be instructive - Question: is it intended that a given skos:Concept be distinct from the (abstract) subject indicated by a published subject indicator assoicated with that concept?

BR

Stuart
--
[1] http://lists.w3.org/Archives/Public/public-esw-thes/2006Nov/0014.html

> -----Original Message-----
> From: public-esw-thes-request@w3.org 
> [mailto:public-esw-thes-request@w3.org] On Behalf Of Bernard Vatant
> Sent: 27 November 2006 18:18
> To: Williams, Stuart (HP Labs, Bristol)
> Cc: Alistair Miles; public-esw-thes@w3.org
> Subject: Re: Concept Equivalence, IFPs, skos:subjectIndicator 
> and owl:sameAs (was Re: SKOS Guide and owl:sameAs)
> 
> 
> Stuart
> 
> You know Alistair just challenged me to sum up the issue in 
> no more than three sentences ...
> I think your answer below is the closest to the target we've 
> achieved so far.
> So let me leverage it and have a try to make it as short as 
> possible (well, a bit more than three sentences, but barely) :
> 
> Issue:
> skos:subjectIndicator being an IFP is likely to cause 
> unwanted merging, whenever skos:Concept designed to be 
> formally different representations of a similar (unformal) 
> concept are inferred to be the same individual (owl:sameAs), 
> based on a common subject indicator value.
> 
> Possible answers:
> 1. Drop skos:subjectIndicator as an IFP.
> 2. Keep skos:subjectIndicator an IFP, but make 
> recommendations about how to use it to prevent unwanted merging.
> 
> <!--End of the contractual three sentences summing up the issue-->
> 
> <!--Discussion-->
> 
> Option 1 is like dropping subjectIndicator altogether. All 
> the point of this property is to be the basis for "same-ness" 
> of a subject (concept). 
> If it's not an IFP, what does it indicate?
> 
> Option 2 can have several variants, among which to use 
> subjectIndicator only for blank concepts, not identified in 
> any concept scheme, to allow indexing assertions of the form: 
> "The subject of this resource is a concept indicated by that 
> other resource".
>     a:thisResource       skos:subject         _:b0
>     _:b0                     skos:subjectIndicator         
> b:thatResource
> 
> <!--End of sum up of discussion so far-->
> 
> More discussion (NEW)
> 
> The above option does not solve the original issue, to 
> express that formally different concepts are somehow 
> representing the same unformal one.
> 
> Side option to solve this issue : use a 
> skos/mapping:broadMatch blank concept, and put the common 
> subject indicator on this broad match
> 
> a:Concept1           skos/mapping:broadMatch       _:b1
> b:Concept2           skos/mapping:broadMatch       _:b1
> _:b1                     skos:subjectIndicator              
> b:thatResource
> 
> Avoiding merging of the two concepts, while providing a way 
> to merge indexing pointers, and answer queries like : find 
> all resources indexed by the concepts "broadly indicated" by 
> b:thatResource.
> 
> How's that?
> 
> Bernard
> 
> 
> Williams, Stuart (HP Labs, Bristol) a écrit :
> > [At Alistair's request I'm reposting this earlier response on-list]
> >
> > Hello Alistair,
> >
> > Thanks... as a SKOS newbie, the thread was useful to me from a 
> > learning pov.
> >
> > One thing you'll spot, if you make it to the end of the thread, is 
> > that I missed the presense of a blank node in the 
> > skos:subjectIndicator example in the guide. The guide presents the 
> > example only in RDF/XML without a diagram - or real mention of the use of a blank node.
> >
> > FWIW I think I came to a tentative conclusion along the following lines:
> >
> > There are two (maybe more) kinds of skos:Concepts: 
> > 1) A 'localised' URI named skos:Concept that one wants to maintain as 
> > distinct from similar concepts in other Thesaurii - because, amongst 
> > other things, they have different pasts and futures. Even at a given 
> > instant they may have subtle difference. In general one wouldn't use 
> > skos:subjectIndicator with this kind of concept (because of its 
> > potential to generate equivalences).
> >
> > 2) A conceptualisation of some published subject (eg. the Isaac Newton 
> > example in the OASIS published subjects document). There could be many 
> > published subject indicator documents for a given subject and in this 
> > case you do indeed want skos:subjectIndicator to be an IFP and bring 
> > about Concept merging (and an effective 'cloning' all the subject 
> > indicators for a given subject). In general the skos:Concept whose 
> > subject is indicated would be a blank node - this would avoid 
> > generation of equivalences between URI named skos:Concepts (by not 
> > giving them URI names :-).
> >
> > I think that with care, those that want to use published subject 
> > indicator can do so without generating unintended equivalences - but 
> > it probably needs clearer motivational examples in the guide.
> >
> > BR
> >
> > Stuart
> >
> >   
> >> -----Original Message-----
> >> From: Alistair Miles [mailto:a.j.miles@rl.ac.uk]
> >> Sent: 23 November 2006 14:59
> >> To: Williams, Stuart (HP Labs, Bristol)
> >> Cc: public-esw-thes@w3.org
> >> Subject: Re: Concept Equivalence, IFPs, skos:subjectIndicator and 
> >> owl:sameAs (was Re: SKOS Guide and owl:sameAs)
> >>
> >> Hi Stuart,
> >>
> >> Quick comment without having read the subsequent thread in detail ...
> >>
> >> I think you have revealed a potential inconsistency in the design of 
> >> SKOS. Certainly worthy of an item in the issues list - I'll do that 
> >> when I get a chance.
> >>
> >> Cheers,
> >>
> >> Alistair.
> >>
> >>     
> >
> >
> >   
> 
> -- 
> 
> *Bernard Vatant
> *Knowledge Engineering
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> *Mondeca**
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>

Received on Tuesday, 28 November 2006 11:50:25 UTC