Re: Using dcterms:hasPart for skos:ConceptScheme hierarchies ?

Hi Bernard,

Catching up on this thread, and following up only to
public-esw-thes@w3.org as per your request...

On Tue, Jun 15, 2010 at 01:07:25PM +0200, Bernard Vatant wrote:
> Sorry for cross-posting, I'd like to attract attention of people from DC,
> ISO and LoC. Please follow-up on SKOS list only to reduce noise.
> 
> SKOS does not make provision for partitive relationships between instances
> of ConceptScheme, such as division of a thesaurus into microthesauri.
> ISO 25964 draft introduces the notion of ConceptGroup and possibility of
> subgroups. But with no RDF model so far.
> Published vocabularies in SKOS such as LCSH use a workaround by declaring
> both the general and particular schemes of a concept, such as :
> 
> <rdf:Description rdf:about="http://id.loc.gov/authorities/sh85060646#concept">
>     ...
>     <skos:prefLabel xml:lang="en">Hierarchies</skos:prefLabel>
>     ...
>     <skos:inScheme rdf:resource="http://id.loc.gov/authorities#topicalTerms"/>
>     <skos:inScheme rdf:resource="http://id.loc.gov/authorities#conceptScheme"/>
>     ...
> </rdf:Description>
> 
> One has to upload all the LSCH vocabulary (quite large) to figure out that
> every other concept declaring <skos:inScheme rdf:resource="
> http://id.loc.gov/authorities#topicalTerms"/> has also a declaration
> <skos:inScheme rdf:resource="http://id.loc.gov/authorities#conceptScheme"/>
> , meaning the extension of the latter includes the extension of the former.
> 
> One would certainly prefer to have this declared up front in an intentional
> way, avoiding the redundant declarations for each concept.
> Seems to me that Dublin Core has provision for such declarations, e.g.,
> 
> <http://id.loc.gov/authorities#topicalTerms>   <http://purl.org/dc/terms/isPartOf>
> <http://id.loc.gov/authorities#conceptScheme>
> and/or
> <http://id.loc.gov/authorities#conceptScheme>  <
> http://purl.org/dc/terms/hasPart <http://purl.org/dc/terms/isPartOf>>  <
> http://id.loc.gov/authorities#topicalTerms>

I think you meant this last part simply to read:

    <http://id.loc.gov/authorities#conceptScheme>  
        <http://purl.org/dc/terms/isPartOf>
            <http://id.loc.gov/authorities#topicalTerms>

> Such declarations could be available under something like
> http://id.loc.gov/authorities.rdf.  BTW currently the two concept scheme
> URIs redirect to the same HTML page at http://id.loc.gov/authorities, so
> there is no formal description of the concept scheme available outside the
> whole LCSH files (quite large, as said above.)
> 
> To sum it up, questions both to DC and SKOS folks
> 
> - Is such a use of dcterms:isPartOf or dcterms:hasPart compatible with the
> letter and spirit of both SKOS and DC ?

>From a DC point of view -- in my opinion -- it looks perfectly
correct.  Also from a SKOS point of view.

> - If yes, could it be raised to the level of recommended practice endorsed
> by both communities?

DCMI does have a body that examines issues related to
semantics -- the Usage Board -- however the Usage Board does
not currently have a mechanism for endorsing practices at this
level of granularity.  Now that the Semantic Web Deployment
Working Group has been closed, on the other hand, the "SKOS
community" does not have a formal, organizational context for
discussing and commenting on questions of recommended practice.

Perhaps this is a problem, and I'd love to hear suggestions
on how we might collectively organize ourselves to provide this
sort of ongoing review of emerging practice, both organizationally
and in terms of human resources.

In the meantime, adopting this approach in a prominent SKOS
implementation such as the ID service at LoC -- and documenting
the rationale for doing so -- would at least provide a good
example that others could follow.

Drilling down a bit further on the suggestion at hand:

> meaning the extension of the latter includes the extension of the former.

This does seems consistent with the definition of isPartOf:

    A related resource in which the described resource is
    physically or logically included.

However, I think you are aiming for a strict logical
interpretation (e.g., "the extension of the latter includes
the extension of the former") -- more than just a case of a
related resource in which the described resource is "more or
less" included.  I think you are aiming for a declaration that
could reliably be used by implementations with the certainty
that the latter precisely includes the former.

If so, then I would have some question as to whether,
in practice, one could expect the guideline to be applied
consistently enough to guarantee that the strict interpretation
were always valid -- especially in cases where concept schemes
(or parts of concept schemes) are continually evolving in a
distributed or loosely coordinated manner.  

Might there be situations in which the logical inclusion of
one scheme within another could be violated by subsequent
developments, rendering originally precise isPartOf statements
only "approximately" correct?  Could this imprecision damage
implementations?  It looks to me, on second glance, like
sorting out a strict formal interpretation could take more
discussion than at first glance seemed necessary...

Tom

-- 
Thomas Baker <tbaker@tbaker.de>

Received on Wednesday, 11 August 2010 18:56:51 UTC