Re: ISSUE-160: Allowing collections in semantic relationships

On Mon, 15 Dec 2008 at 15:08:01, Antoine Isaac <aisaac@few.vu.nl> wrote
>Hello everyone,
>
>I'm coming back to this issue, as I took the following action on me:
>
>>    [PENDING] ACTION: Antoine to write something in Primer wrt. ISSUE 
>>160 [recorded in 
>>[37]http://www.w3.org/2008/12/02-swd-minutes.html#action14]
>
>I have come with two paragraphs at the end of this mail, to add at the 
>end of the section on Collections in the SKOS Primer [1]. I hope that 
>they capture the main lessons that can be learnt from this very 
>interesting discussion. Feedback is more than welcome!
>
>Note that I would prefer not to mention explicitly Johan and Leonard's 
>solutions, as I feel they would add much detailed for the Primer, and 
>maybe also too much BS-8723 oriented. But it's clear they'd be welcome 
>to appear as best practice notes somewhere...
>
>Best,
>
>Antoine
>
>[1] http://www.w3.org/TR/skos-primer/#seccollections
>
>======== beginning of added paragraphs
>
>One may wonder whether using collections is desirable, as they add 
>complexity to the representations applications have to manipulate. In 
>fact, for some cases, e.g. when KOS are mainly intended as navigation 
>hierarchies, it seems more intuitive to represent "node labels" or 
>"guide terms" as instance of skos:Concept, and to use normal semantic 
>relationships for linking them to other concepts. Take the following 
>variant of the "milk" example:
>
>ex3:milkBySourceAnimal rdf:type skos:Concept;
>  skos:prefLabel "milk by source animal"@en;
>  skos:broader ex3:milk;
>  skos:narrower ex3:cowMilk;
>  skos:narrower ex3:goatMilk;
>  skos:narrower ex3:buffaloMilk.
>
>The choice between the two representation options remains open, 
>depending on the application at hand. Readers should however be aware 
>that not using collections, even if more intuitive, may result in a 
>harmful loss of semantic accuracy. For many description applications, 
>for instance, "node labels" are entities of really specific nature, and 
>must not be used as object indices alongside "normal" concepts. 
>Representing them as mere concepts is therefore clearly not a best practice.
>
>======== end of added paragraphs
>
Treating node labels as concepts is not just "not a best practice" - it 
is logically wrong and misleading.

If SKOS is just to be used for the generation of hierarchical displays 
then this fudge can be used, but I thought that it was more than that 
and was concerned with the accurate representation of semantic 
relationships - witness the extended discussion of the distinction 
between "broader" and "broader transitive", for example.

Doing it properly may be slightly more complicated, but that is because 
the semantic relationships are more complicated. I don't think you can 
ignore them. If you just want to generate displays you don't need SKOS 
at all, you can just use simple tags like BT/NT/RT, which give a much 
simpler exchange format that has served us well in many applications up 
to now.

I'm also concerned that you say that a more complete representation is 
"maybe also too much BS-8723 oriented". Is that a bad thing? In fact it 
would be better if it were more ISO 25964 oriented, following the model 
attached to my message of 4th December, which is a later development of 
the BS-8723 model and which makes the important distinction between 
"arrays" and "concept groups".

I am really keen that if SKOS is to become a de facto standard for the 
exchange of thesaurus data it should be capable of modelling all the 
elements of a modern thesaurus that complies with standards. If you 
don't like our model, please tell us what is wrong with it; if you do, 
why not use it?

You did say "feedback is more than welcome"!  :-)

Leonard
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Received on Monday, 15 December 2008 22:37:33 UTC