RE: Broader, collections and the difference between SKOS and OWL

Interesting issues and discussion.
I add my 2 cent comment, just to double check my view is correct:
 
- I think what SKOS try to do is to represent thesauri and other KOS in a
more formal way (machine processable) and in doing this SKOS try to define
better the distinction between concepts (in ontological sense) and terms
(let's say lexicalizations for the concepts). (this distinction is not clear
into a thesaurus)
 
- in fact there are relationships between skos classes (representing the
BT/NT/RT-->associative) and also relationships between terms for the same
concepts (prefLabel and altLabel are one example, but there are others).
 
This is my view... So what i see is that SKOS is a kind of intermediary step
from non-concept (=classes) organized structures (thesauri) to fully well
classes/instances/properties/etc organized structures (such ontologies in
OWL).
 
Am I correct?
 
Thanks
Margherita
 

 -----Original Message----- 
 From: public-esw-thes-request@w3.org on behalf of Jane Greenberg 
 Sent: Mon 18/02/2008 06:28 
 To: SKOS 
 Cc: Simon Spero 
 Subject: Re: Broader, collections and the difference between SKOS and
OWL
 
 


 Greetings... all ... I am new to this list, although I have been
following
 SKOS development for a longer time.
 
 Simon:  You bring up a critical issue, and I'm really pleased to see
 attention to this point.
 
 Two observations I'd like to share:
 
 1. Section 2.3.1 of the SKOS Primer is (in my opinion) problematic
for the
 very reasons Simon points in his email.
 
 The notion of '"dirtier" hierarchies' conflicts of the meaning of the
 concept of "hierarchy", and does *not* follow thesaural and taxonomic
 standards.
 
 The KOS/vocabulary community has very strict rules for hierarchy and
the
 BT/NT hierarchical relationships must pass the test of "true"
inheritance
 within the scope of the domain (or world) being represented.
 
 Vocabulary creators need to describe the world they are representing.
 
 Allowing for "dirtier" hierarchies will create a mess and interfere
with
 the potential for interoperability among SKOS schemes in general or
 with any OWL schemes.
 
 Basically a concept/class "is" or "is not" a hierarchy.  If something
is
 to be classed as a dirty hierarchy, it really ought to be considered
an
 "associative relationship".  It seems to me efforts need to be
directed to
 considering specific types of associations...e.g. process/product,
 activity/agent, and so forth, an area I'd be pleased share more about
if
 anyone is interested.
 
 2. I don't believe it matters if you/we/anyone uses the word
 class/concept/term, although they are not "equivalent" in the sense
of a
 true thesauri ;)  wink!
 
 A term represents a concept, and it can be referred to as a class in
an
 abstract sense.
 
 As you all know, we could use the word object or resource too...for
the
 "entities" being represented w/SKOS.  What ever "x" is used, it needs
to
 be used consistently.
 
 Having shared this observation, I would discourage the use of the
word
 "subject term" or "subject heading" for two reasons.  First, SKOS can
be
 used for named entities that may be used to represent (1.) embodied
 thought (simply descriptive cataloging)--physical/observable and
measurable
 aspects of an object, and (2.) expressed thought (simply
 intellectual/subject analysis).  Second, subject headings, as you
know,
 are ugly yet very creative beasts dealing with syntagmatic
structuring.
 Subject headings are not suited for SKOS in the raw, although a SKOS
 scheme could help build subject headings following a protocol.
 
 thanks for reading and letting me chime in.
 
 peace! jane
 
 
 
 
 On Fri, 15 Feb 2008, Simon Spero wrote:
 
 > [I'm currently working on a more formal model, but I wanted to post
an
 > outline to get some feedback (and to keep me away from LaTeX
related
 > avoidance behavior :) .
 >
 > The key point is that SKOS Concepts do not correspond directly to
 > concepts/classes but instead more closely resemble Subject Terms.
If
 > this distinction is taken into  account, and the relationship
between
 > the SKOS Concept and its associated class is explicitly modeled,
many
 > outstanding issues with SKOS become much easier to resolve cleanly.
 >
 > ]
 >
 > 1: Svenonius on Subject Terms.
 >
 > Subject language terms differ referentially from words used in
ordinary
 > language. The former do not refer to objects in the real world or
 > concepts in a mentalistic world but to subjects. As a name of a
subject,
 > the term Butterflies refers not to actual butterflies but rather
to
 > the set of all indexed documents about butterflies. (Svenonius
2000, p.
 > 130)
 >
 > 2: SKOS Concepts are Svenonian Subject Terms, not concepts.
 >
 > 3: The extension of a SKOS Concept is the set of all documents
which
 > have that SKOS Concept as a subject; compare with the definition of
an
 > rdfs class in RDF Semantics (Hayes 2004)
 >
 > 4: Concept schemes are defined in the context of a specific domain
 > (which may be general).  Relationships need not be valid outside
that
 > domain (Turbine/Fan/Blades ISO; Parrots BT Pets in a pet shop
 > thesaurus).
 >
 > 5: Relationships between SKOS Concepts are relationships between
Subject
 > Terms, not Classes.   These relationships entail a different set of
 > relationships between the  Classes associated with those Subject
Terms.
 >
 > 6: Every hierarchical relationships between Subject Terms in
Controlled
 > Vocabularies must be transitive by definition. The relationships
they
 > entail between underly classes need not be.  Transitivity across
 > different subtypes of hierarchical relationships is only valid at
the
 > level of their least common subsumer.
 >
 > [ A hierarchical relationship] is assigned to a pair of terms when
the
 > scope of one of the terms totally includes (is broader than) the
scope
 > of the other. (Dextre Clarke 2001, p. 42)
 >
 > There seems to be no particular logical reason why the part-whole
 > relationship should not be generally applicable. It only has to
meet the
 > test of always being true, just as with the other hierarchical
 > relationships. (Milstead 2001, p.60)
 >
 > This test of total inclusion is a rigid property of hierarchical
 > relationships.   Given that associative relationships are defined
 > negatively as relationships which are neither hierarchical nor
 > equivalence, and  that the standards specify that relationships
that are
 > not truely broader are associative, an intransitive skos:broader
cannot
 > be disjoint with skos:related.
 >
 > 7:   A  skos:broader B  means: every document  ( within the domain
of
 > the concept scheme) about A must also be about B.    Thus:
 >
 > Wheels BT Cars   == Every document   about wheels is also a
document
 > about cars.
 > Cars BT Vehicles == Every document about cars is also a document
about
 > vehicles.
 >
|----------------------------------------------------------------------------
------------------------------------
 > Wheels BT Vehicles == Every document about wheels is also a
document
 > about vehicles
 >
 > It is incorrect to infer any relationship between the class of
Wheels
 > and the class of Vehicles given only a plain broader/BT assertion
 >
 > 8:   A BTG B means:  every document about A must also be about B
because
 > the class of As is a subclass of the class of Bs.
 >
 > Cars BTG Vehicles == Every document about cars is also about
vehicles,
 > because a car is-a vehicle.
 > Convertibles BTG Cars == Every document about convertibles is also
about
 > cars, because  a convertible is a car
 >
|----------------------------------------------------------------------------
------------------------------------------------------------------------
 > Convertibles BTG Vehicles == Every document about convertibles is
also
 > about vehicles, because a convertible is a vehicle
 >
 > 9: A BTP B means:  every document about A must also be about B,
because
 > every A is in some sense part of a B.
 >
 > Fingers BTP Hands == Every document about fingers  is also about
Hands,
 > because every finger is part of a hand.
 > Hands BTP People == Every document about hands  is also about
People,
 > because every hand is  part of a person.
 >
|----------------------------------------------------------------------------
------------------------------------------------------------------------
 > Fingers BTP People == Every document about fingers is also about
People,
 > because every finger is part of a person.
 >
 > 10:  The exact relationship between the classes of two SKOS
Concepts
 > that are BTP depends on the nature of  partitive relationship.
Some
 > subtypes of BTP may allow a more precise transitive semantics for
the
 > related Classes.
 >
 > 11:   A BTI B means:  every document about the individual A is also
 > about B, because A is an instance of  B.    BTI is subset of BTG;
thus
 > transitivity is maintained for the underlying classes
 >
 > My S2000 BTI Convertibles == Every document about my S2000 is also
about
 > Convertibles, because my S2000 is-a convertible
 > Convertibles BTG Cars == Every document about convertibles is also
about
 > cars, because  a convertible is-a car
 >
|----------------------------------------------------------------------------
------------------------------------------------------------------------
 > My S2000 BTI Cars == Every document about my S2000 is also about
cars,
 > because my S2000 is-a car
 >
 > 12: SKOS Collections correspond to arrays, and to what Svenonius
termed
 > "perspective hierarchies".    These types of hierarchies are useful
for
 > representing classificatory structures; it might be possible to
infer
 > quasi-facets , or specific properties.
 >
 > More to come
 >
 > Simon
 >
 >
 > References
 > Hayes, Patrick (2004). RDF Semantics. Recommendation. World Wide
Web
 > Consortium.
 > URL: http://www.w3.org/TR/2004/REC-rdf-mt-20040210/

 >
 > Milstead, Jessica L. (2001). “Standards for Relationships between
Sub
 > ject Indexing Terms”. In: Relationships in the Organization of
 > Knowledge. Ed. by Carol A Bean and Rebecca Green. Information
science
 > and knowledge management. Dordrecht: Kluwer Academic Publishers.
Pp.
 > 53–66. ISBN: 0792368134.
 >
 > Svenonius, Elaine (2000). The Intellectual Foundation of
Information
 > Organization. Cambridge, Mass.: MIT Press. ISBN: 0262194333 (hc :
alk.
 > paper).
 > URL: http://www.netlibrary.com/AccessProduct.aspx?ProductId=39954.

 >

Received on Monday, 18 February 2008 06:49:45 UTC