Re: Relationships involving collections

Hi Leonard,

Perhaps it is my lack of knowledge in forming/modelling vocabularies, 
but I am now very confused as to what the purpose of a collection 
(called an array in [3]). Would it be fair to say that they should be 
used with extreme caution and rarely? Are there definite use cases where 
they should and should not be used? I'm getting the impression that they 
are not used to further clarify the hierarchy.

Cheers,

Alasdair

[3] http://www.willpowerinfo.co.uk/glossary.htm

Leonard Will wrote:
> On Tue, 5 Feb 2008 at 10:03:09, Alasdair Gray <agray@dcs.gla.ac.uk>
> wrote
>   
>> With regard to the latest skos reference working draft, how should
>> mappings between vocabularies that involve collections be performed?
>>
>> In the astronomy vocabularies that I have been working with, I have come
>> across several instances where I either need to directly relate 2 collections
>> or a collection with a concept. One such example is for relating the
>> vocabulary of astronomy and astrophysics journal keywords (A&A) [1] with
>> the international astronomical union thesaurus (IAUT) [2]. Below are brief
>> snippets of the two vocabularies.
>>
>> A&A
>> Concept: "Sources as function of wavelength"
>> NT Collection: "Gamma Rays"
>>   NT Concept: "Gamma ray bursts"
>>      Concept: "Gamma ray observations"
>>      Concept: "Gamma ray theory"
>>
>> IAUT
>> Concept: "Radiation"
>> NT Concept: "Gamma rays"
>>
>> I would like to assert
>> A&A:"Gamma Rays" skos:exactMatch IAUT:"Gamma rays"
>>
>> In fact, as I have typed up this example I wonder if the A&A vocabulary
>> snippet I have given is in fact valid in the new skos reference as is declares
>> a collection to be a narrower term and this goes against the domain and
>> range declarations for the BT/NT relationships.
>>     
>
> Well, I don't know about SKOS, but the structures above do not conform
> to the thesaurus standard BS8723-2. They should be something like this:
>
>
> [A&A]
> radiation sources
>     (radiation sources by wavelength)
>     NT  gamma radiation sources
>         visible radiation sources
>         microwave radiation sources
>
> gamma radiation sources
>     RT gamma rays
>
> gamma radiation
>     USE gamma rays
>
> gamma rays
>     NT  gamma ray bursts
>     RT  gamma ray observations
>         gamma radiation sources
>         gamma ray theory
>
> [IAUT]
> radiation
>     NT gamma rays
>   
> You have shown "Gamma rays" as "Collection", but I hope that nobody
> would interpret it as that, in SKOS or elsewhere. It looks like an
> ordinary concept, and doesn't become a "collection" just because it has
> some narrower terms. As I understand it, "collection" is the SKOS term
> for what the thesaurus standard BS8723-1 calls an "array": a group of
> sibling terms. An array may be preceded by a node label showing a
> "characteristic of division", e.g. (... by wavelength) in the above
> example. Node labels are just interpolated explanatory labels; they do
> not represent concepts and they do not have relationships.
>
> You can't really make mappings between an array and a concept. If you
> want to map the whole group, you should probably be mapping their parent
> term. In this case the concept "gamma rays" occurs in both thesauri, and
> as its definition is presumably the same in both there should be no
> problem in making a direct mapping.
>
> It looks as though the thesauri you are working with are not well
> structured, having invalid NT relationships, so problems are inevitable.
> :-(
>   
> Leonard Will
>
>