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Re: SKOS primer section 3.3 and DCAM VocabularyEncodingScheme

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Thu, 28 Jan 2010 08:52:57 +0100
Message-ID: <4B614259.5020601@few.vu.nl>
To: "Houghton,Andrew" <houghtoa@oclc.org>, SKOS <public-esw-thes@w3.org>
Hi Andy,

>> From: Antoine Isaac [mailto:aisaac@few.vu.nl]
>> Sent: Wednesday, January 27, 2010 01:42 PM
>> To: Houghton,Andrew
>> Cc: public-esw-thes@w3.org
>> Subject: Re: SKOS primer section 3.3 and DCAM VocabularyEncodingScheme
>> 1. it would maybe call for a more precise characterisation: is
>> skos:ConceptScheme really a subClassOf dcam:VocabularyEncodingScheme?
>> Isn't it the opposite? Could they be equivalent? Honnestly I don't know
>> enough DCAM to answer, but I'd be interested in having a clearer view
>> ;-)
> I agree there isn't a clear answer here and that is why I'm concerned
> with what I'm trying to do and its implications.  Maybe the SKOS
> working group should get together with the DCMI folks ot iron this
> out.
>> 2. there's something weird with your examples. According to your
>> definition of<class/123.4>,<scheme/ddc22>  is an *instance* of both
>> skos:ConceptScheme and dcam:VocabularyEncodingScheme. Which is fine.
>> But in the lines above you say that<scheme/ddc22>  is a subclass of
>> dcam:VocabularyEncodingScheme, which does not fit.
>> Similarly, your first example (in XML) seems to hint that the object of
>> your dct:subject statement is an *instance* of dct:DDC, not a *member
>> of* it.
> DCAM takes the same approach that SKOS takes.  You declare something a
> scheme, e.g., skos:ConceptScheme vs. dcam:VocabularyEncodingScheme, but
> membership is via a property in a resource.  So<scheme/ddc22>  is a
> skos:ConceptScheme that subclasses dcam:VocabularyEncodingScheme.
> Members must be related to the scheme, e.g., skos:inScheme vs.
> dcam:memberOf, so even though skos:ConceptScheme is a subclass of
> dcam:VocabularyEncodingScheme relating members with just skos:inScheme
> would relate a member to skos:ConceptScheme but not
> dcam:VocabularyEncodingScheme.  Hence, both assignments.

You got my comment wrong, Andy! I do agree with your two RDF statements, at least until you've not declared skos:inScheme a subproperty of dcam:memberOf, as you suggest ;-)

What I was puzzled by is that in some parts of your example, you seemed to have specified:
1. that a specific vocabulary (DDC) was itself a subclass of dcam:VocabularyEncodingScheme:
> <scheme/ddc22> a skos:ConceptScheme ;
>   rdfs:subClassOf dcam:VocabularyEncodingScheme .

2 and that a specific concept (123.4 in DDC) was an instance of that scheme:
> <dct:subject>
>   <dct:DDC>
>     <rdf:value>123.4</rdf:value>
>   </dct:DDC>
> </dct:subject>

which of course contradicts with the end of your example, which I would say is correct:
> <class/123.4> a skos:Concept ;
>   skos:inScheme <scheme/ddc22> ;
>   dcam:memberOf <scheme/ddc22> .



> Hmm... perhaps I also need to make skos:inScheme a subproperty of
> dcam:memberOf, then I could just use skos:inScheme and dcam:memberOf
> could be inferred.
> Thanks for your response, Andy.
Received on Thursday, 28 January 2010 07:53:32 UTC

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