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RE: Doubts about domains and microthesauri in Thesaurus to SKOS conversion

From: Johan De Smedt <Johan.De-smedt@tenforce.com>
Date: Sun, 21 Feb 2010 10:38:05 +0100
To: "L.Will@willpowerinfo.co.uk" <L.Will@willpowerinfo.co.uk>, Giacomo Bartoloni <geco82@gmail.com>
CC: "public-esw-thes@w3.org" <public-esw-thes@w3.org>, Enrico Francesconi <francesconi@ittig.cnr.it>
Message-ID: <B433CF38970EC14EA2B3A08075A5FA7B3C5CDCA1A3@tfvirt-prdexch.tenforce2.be>
Three alternatives and some considerations:

1)
The modeling of sub-thesauri in skos would be facilitated if a skos:Collection need not be disjoint with a skos:ConceptScheme.
This would allow for different sub-classes of skos:Collections
- collections that represent arrays
- collections that represent sub concept schemes or ISO like concept groups.
Note: I would NOT favor this because
- the skos:member relation mixes the skos:Collection and skos:Concept members of a collection.
- skos:Collection and skos:ConceptScheme scheme are disjoint classes
  Thus making a micro-thesaurus a skos:Collection would effectively not allow to model a micro-thesaurus as a skos:ConceptScheme.
  Occasionally this is not helpful because a micro-thesaurus does is a thesaurus when taken on its own.
- it would mean a change of the recommendation (while other alternatives are available - see 2)

2)
A new class ConceptGroup may be specified:
- Having subGroup/superGroup hierarchy possibilities next to membership
- A Concept Group would not be disjoint from skos:ConceptScheme
Note: this would be more close to the ISO DIS model Leonard refers to.
Considerations:
If some skos extension would define skos-ext:ConceptGroup, with:
- skos-ext:subGroup/superGroup properties establishing the hierarchy between these groups
- a skos-ext:inConceptGroup establishing concept group membership,
then the EUROVOC ontology can take that into account as follows:
- ev:Domain and ev:MicroThesaurus would be sub-class of skos:ConceptGroup
- the properties ev:domain/ev:microThesaurus structuring the Domain/Microthesaurus hierarchy would become sub properties of skos-ext:subGroup/superGroup
- <a-skos-ext:ConceptGroup-uri> skos:inScheme <a-skos:ConceptScheme-uri> declares the subject skos-ext:ConceptGroup to be defined by the object skos:ConceptScheme

3)
A separate top-level taxonomy/concept-scheme can be defined to establish the domain/micro-thesaurus (or any thesaurus top-level organization) hierarchy.
A sub-property of dc:subject (e.g. skos-ext:subjectMatch) could be applied to map the concepts of the original thesaurus to concepts of top-level (domain/micro-thesaurus) thesaurus.
The sub-property would need to define the semantics of concept-group membership.
This approach
- allows multiple classification hierarchies to be applied to an existing thesaurus.
- makes the original thesaurus independent from the used top-level classification hierarchy.
- looses the semantics that a top-level concept (domain or microthesaurus) actually can be considered as a thesaurus.
  (at least in the skos universe because skos:Concept and skos:ConceptScheme are disjoint)
I would not favor this approach for a thesaurus top level organization.
- This alternative belongs more on the problem area of matching and mapping thesauri.
- skos core has a nice arsenal of (matching) properties to handle this problem area.
- The top-level organization of thesauri can be handled as explained in 2.

Johan.

> -----Original Message-----
> From: public-esw-thes-request@w3.org [mailto:public-esw-thes-
> request@w3.org] On Behalf Of Leonard Will
> Sent: 20 February, 2010 19:04
> To: Giacomo Bartoloni
> Cc: public-esw-thes@w3.org; Enrico Francesconi
> Subject: Re: Doubts about domains and microthesauri in Thesaurus to
> SKOS conversion
> 
> On 2010-02-18 15:11, Giacomo Bartoloni wrote:
> > Hi everybody, I'm studying the best way (or the most beautiful and
> > meaningful form) to represent a thesaurus with domains and
> > microthesauri, in my case Eurovoc and few ones, in "SKOS 2009"
> format.
> > My doubt is how to deal with domains and microthesauri, I found many
> > examples (UKAT's, IVOA vocabularies and STW's) but it seems to lack a
> > shared method to do it.
> > In UKAT thesaurus both the thesaurus and the microthesauri are
> > skos:ConceptScheme and the concepts have the property skos:inScheme
> > pointing to the main scheme and to the related microthesaurus.
> > According to IVOA all the domains and the microthesauri are
> > skos:Concept but I think that in this way I loose the base thesaurus
> > Descriptor goal and I put all domains, microthesauri and descriptors
> > on the same level.
> > In the STW's thesaurus, there is only one skos:ConceptScheme, the
> > thesaurus itself, and the domains, the microthesauri and the
> > descriptors are mapped into skos:Concept but this class is extended
> > into stw:Descriptor and ztw:Thsys.
> >
> > Which is the best thesaurus representation?
> >
> > Thanks a lot
> >
> > Giacomo Bartoloni
> >
> You might be interested to see the draft ISO 25963-1 data model, which
> I
> attach. This contains some elements that are not (yet) implemented in
> SKOS, such as ThesaurusArray and ConceptGroup.
> 
> Arrays are sets of sibling terms, often grouped or ordered by some
> "characteristic of division" specified in a "NodeLable", whereas
> ConceptGroups are collections of concepts which may not be
> hierarchically related to each other, but may be subsets of the whole
> thesaurus, such as microthesauri or domains.
> 
> These are described in more detail in the draft standard, which is
> available for comment until 28th February 2010 on the British Standards
> Institution web site at <http://drafts.bsigroup.com/> (Free
> registration
> required). Have a look at paragraphs 15.2.17 and 15.2.18.
> 
> I hope that someone will come up with a way of incorporating these and
> other parts of the ISO model into SKOS as extensions or additions if
> necessary. I haven't yet worked out whether the The EUROVOC Thesaurus
> Ontology Schema that Johan de Smedt sent is consistent with the ISO
> model, but would be glad so see any comments.
> 
> Leonard Will
> 
> --
> Willpower Information     (Partners: Dr Leonard D Will, Sheena E Will)
> Information Management Consultants            Tel: +44 (0)20 8372 0092
> 27 Calshot Way                              L.Will@Willpowerinfo.co.uk
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Received on Sunday, 21 February 2010 09:38:46 UTC

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