Re: SKOS transitive hierarchical relations

The fact that SKOS is an RDFs application put on the boundaries of OWL 
is sometime creating confusions...

Could I emphasize that there is a need to organize terminology for the 
specific operations done by machines in direct relations with humans?
OWL is about structured data representation, automated reasoning: 
machine to machine communications.
SKOS may be part of this (I am not fully involved on that aspect) but it 
is ALSO (mainly in my point of view) a tool for Information Scientists 
(that you call Librarians!) to organize relations between information 
resources and HUMANS (more precisely between Human terms and Machine 
Coded concepts: VoID may be a way to organize relations between 
resources and concepts).

I insist on this distinction and encourage you to discover the world of 
complexities in the man/machine relations for discovery, learning, story 
organization, concept identification, authoring, publication... SKOS is 
part of that. SKOS should always be able to represent a thesaurus (some 
problems remaining). A thesaurus may be built respecting or not the 
rules for an ontology (in its OWL related meaning) but at least SKOS 
respects RDFS rules for information encoding.

For "humans", Broader/Narrower relations are used to indicate "For an 
user asking resources for a given concept, every resources linked to a 
transitiveNarrowers may interest him/her if an "expanded" search is 
requested"

The Turbine Blade example is interesting: it can be ontologically a 
specialization of concepts Turbine and Blade (and one will probably wish 
to specify "how" a Turbine Blade is a Blade and "how" a Turbine Blade is 
a Turbine). But for Information Management, Turbine Blade may be only a 
Narrower of Turbine (If you want to learn about Blades, it may be judged 
that literature about Turbine Blades is not DIRECTLY interesting for 
you; but if you ask for "Turbines", then "Turbine Blades" may be judged 
as always relevant).

It is easier to build a thesaurus using ontologically supported relations.
But in Medicine and Humanities, it becomes much more difficult:
http://www.nlm.nih.gov/mesh/meshrels.html
    (in the MeSH hierarchies, NLM even make one intended BT/NT loop 
between "Moral" and "Ethic" !)

With chemistry, one can organize molecules in different hierarchies:
* their structure
* their use
* their impact on human
* their different classifications
etc.

Some of us are fighting to have machines reason better (A.I.), some 
others are worried about humans (Natural Intelligence!).

I think that "Application Profiles" remains an important investigation 
field to improve SKOS and adapt it to different situations.
What do you think?

Christophe

Le 5/01/2012 09:58, Vincenzo Maltese a écrit :
> 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.
>
> +1,
> Enzo
>
>
>> The problem that with the second version of SKOS (as opposed to the
>> original, SME-focused, draft that was stable for about four years) is that
>> the traditional  semantics of controlled vocabularies as standardized in
>> (e.g. ISO 2788) were rejected, without a corresponding recognition that
>> the
>> semantics were being changed.
>>
>> The traditional domain of interpretation for controlled vocabularies is
>> #$ConceptualWork; the skos:broader relation in the SME developed
>> vocabulary
>> corresponded to BT (Broader Term) in controlled vocabularies.
>>   Undifferentiated BT is a relationship between subject vocabulary terms,
>> and not between #$Collection in an underlying ontological theory.
>>
>> BT is sometimes referred to in the literature as The Hierarchical
>> Relationship; Associative relationships (RT, or skos:related) are the
>> residual category of relationships that are neither that of equivalence
>> nor
>> hierarchical.
>> The defining characteristic of hierarchical relationships is that they are
>> always true - under NISO standards, intensionally, under ISO 2788
>> extensionally for the domain of documents to which the definition applies
>> (illustrated in the acceptability and classification of the the turbine -
>> blade example).
>>
>> IT was decided that an essential use case for SKOS required that A broader
>> B, B broader C  and not A broader C ; it was also decided that the
>> semantics of broader were not changed by this (a deliberate decision was
>> made not to change the namespace). I must confess that I am still not
>> clear
>> on how this is possible, or what broader actually means.
>>
>> If you want to capture the semantics of Broader Term using the SKOS
>> vocabulary, you should assert broaderTransitive and ignore the suggestions
>> in the primer. UMBEL has been doing the right thing.
>>
>> Simon
>> Simon
>>
>
>
>

Received on Thursday, 5 January 2012 10:37:32 UTC