Re: SKOS transitive hierarchical relations

Hi Simon,


> On Thu, Jan 5, 2012 at 3:58 AM, Vincenzo Maltese
> <maltese@disi.unitn.it>wrote:
>
>> Dear Simon, all,
>> I'm surely not an expert of SKOS, nor a librarian, but at the latest UDC
>> seminar I participated I tried to bring the point of view of my research
>> group (working in knowledge representation and reasoning) in which we
>> tried to formalize the meaning of the BT\NT relations.
>>
>> We interpret them as superset/subset and let them correspond to
>> subsumption in description logic were the interpretation of each node in
>> the vocabulary is the set of documents about the node. Now, since both
>> subset and subsumption are transitive, this works only for transitive
>> BT\NT relations. We treat non transitive BTs as associative relations.
>>
>
> This is mostly correct; associative relationships should be used where the
>  relationship is not  necessarily transitive for the applicable domain of
> discourse (which is either the subject area for which the thesaurus is
> defined (ISO 2788), or the entire bibliographic universe (NISO
> Z39.19:2005).
>
> Note that the key distinction between Knowledge Organization Systems and
> Knowledge Representation systems is that the latter have extensions that
> arbitrary things, whereas KOS's are extensional over Conceptual Works...
> Word and Subject v. Word and Object.  Or to put it another way...
> http://www.ibiblio.org/ses/anyqs.jpg

That's great. This is actually what we call classification semantics (for
KOS) vs. real world semantics (for KR). We automatically compute the first
from the second [1].

[1] http://eprints.biblio.unitn.it/archive/00002214/01/techRep466.pdf

Enzo

>
> BTW, to clarify the Turbine and  Blade example;
>
> Under the ISO rule, for a thesaurus specific to the domain of documents
> about turbines, if all documents about blades are necessarily documents
> about things which are parts of turbines, the vocabulary engineer may use
> the BT relationship, since there cannot exist documents about blades which
> are not about turbines.  This relationship is prohibited under NISO
> Z39.19:2005.
>
> Transitivity of NT does not entail any relationship between co-hyperonyms
> of a given subject.
> e.g.
> (Turbine Blade NTP Turbine) AND (Turbine Blade NTG Blade) |= (Blade NT
> Turbine)
>
> (Parrots as Pets NT Parrots) AND (Parrots as Pets NT Pets) |= (Parrots NT
> Pets) OR (Pets NT Parrots).
>
> That most parrots in Western Europe and the US are pets is not expressible
> in a monotonic, non-probabilistic   ontology language.  More expressive
> languages can express this. PR-OWL (Kathy Lasky, Paulo Costas, and their
> students) can conditionalize the probabilities (P(Parrot is Pet | Location
> is Fairfax, VA) = 0.95); a system like Cyc can add the axiom as a default
> within a microtheory specialized to urban areas (Parrots that are not
> abnormal are  Pets).  Abduction can also allow one to hypothesize that a
> Parrot is a Pet, but that situation is better handled through a
> probabilistic reasoner.
>
> Part of the problem with the way that SKOS handles broader^* is that the
> current rationale is based on  epistemic/doxastic/illocutionary  concerns
> that could arise when using a reasoner that cannot could not distinguish
> between inferred and asserted object property values.  Since this
> information is part of the OWL API (cf
> OWlIndividual.getObjectPropertyValues<http://owlapi.sourceforge.net/javadoc/org/semanticweb/owlapi/model/OWLIndividual.html#getObjectPropertyValues(org.semanticweb.owlapi.model.OWLObjectPropertyExpression,
> org.semanticweb.owlapi.model.OWLOntology)> with
> OwlReasoner.getObjectPropertyValues<http://owlapi.sourceforge.net/javadoc/org/semanticweb/owlapi/reasoner/OWLReasoner.html#getObjectPropertyValues(org.semanticweb.owlapi.model.OWLNamedIndividual,
> org.semanticweb.owlapi.model.OWLObjectPropertyExpression)> )this does not
> seem to be a problem with the reasoners in current use.
>
> If the  underlying problem  is how to handle vocabularies that use BT
> incorrectly, better approaches are to either fix the vocabulary (if the
> vocabulary is supposed to be using BT in a standard form), or, if that is
> not possible, to translate the relations accidentally labeled as BT as
> being associative.  This is the treatment for quasi and pseudo broader
> relationships prescribed in the standards.
>
> Simon
> p.s.
>   There are possible psychological reasons to doubt the cognitive validity
> of the broader term relationship, but these reasons are explicitly blocked
> in the Standard's definitions of controlled vocabularies (most questions
> arise out of  polysemy and from prototype effects in psychological
> concepts).
>

Received on Thursday, 5 January 2012 18:45:31 UTC