RE: [Proposal][SKOS-Core] skos:denotes

Ok, so you're talking about the class/instance issue, right?

You're saying that OWL classes and foaf classes for example can be used in 
the range of the rdf type property. So that a resource may be of *type* 
person.
And you're saying that naturally skos Concept *instances* (e.g. 
myskos:Person - a skos concept that represents the concept of a Person 
(?!)) can*not* be used in the range of the rdf type property.

So you're saying, for these cases, that in order to indicate e.g. a 
foaf:Person (class) has some association with e.g.myskos:Person (instance) 
we need a skos:denotes property in SKOS Core.

I get this logic. But I still don't get why this is machinery is so 
important. When do we want to query RDF data in a way such that we need 
skos:denotes? It must be blindingly obvious, but please point it out to me, 
gimme an example!!

/me thinks further: is it that we might want to phrase RDF queries such 
that we effectively ask "this foaf:Person class, what concept does it 
relate to?..."

Thanks
Nikki



--On Friday, October 01, 2004 11:57:06 +0100 "Miles, AJ (Alistair) " 
<A.J.Miles@rl.ac.uk> wrote:

>
> How about this for an argument as to why resources of type skos:Concept
> are at a different level of abstraction to, say for example, resources of
> type foaf:Person ...
>
> You would not say that a 'scopeNote' or a 'definition' is a property of a
> person.
>
> However, you might reasonably say that an 'email address' or 'date of
> birth' is a property of a person.
>
> Al.
>
> ---
> Alistair Miles
> Research Associate
> CCLRC - Rutherford Appleton Laboratory
> Building R1 Room 1.60
> Fermi Avenue
> Chilton
> Didcot
> Oxfordshire OX11 0QX
> United Kingdom
> Email:        a.j.miles@rl.ac.uk
> Tel: +44 (0)1235 445440
>
>
>
>> -----Original Message-----
>> From: public-esw-thes-request@w3.org
>> [mailto:public-esw-thes-request@w3.org]On Behalf Of Dave Reynolds
>> Sent: 30 September 2004 18:38
>> To: Matthews, BM (Brian)
>> Cc: 'public-esw-thes@w3.org'
>> Subject: Re: [Proposal][SKOS-Core] skos:denotes
>>
>>
>>
>> Matthews, BM (Brian) wrote:
>>
>> > As I interpret this,  this gives the best semantics I know of for
>> > Thesaurus concepts - a concept's denotation is "the set of
>> resources
>> > which are classified under that concept" (my words).  This is quite
>> > different from the intended use in Ontologies, where instances are
>> > "supposed" to stand for "real-world" things (with suitable
>> philosophical
>> > quotation marks).
>>
>> I agree with that summary of the semantics of Thesaurus
>> concepts but I'm
>> not so sure ontologies are that different. Sure in
>> philosophical terms
>> ontologies are more than that, as you say, but in practical
>> RDFS and OWL
>> terms a class is just a set of instances and an instance is just a
>> "resource". It so happens that OWL gives you some machinery
>> for identifying
>> the class of a resource by its properties, and RDFS gives you
>> less, but the
>> difference between those and your semantics for Thesaurus
>> concepts is just
>> a matter of expressivity rather than of fundamental nature.
>>
>> Personally I find this article nicely captures this view that
>> they are just
>> a continuum with different expressivity and degree of formality:
>> http://www.metamodel.com/article.php?story=20030115211223271
>>
>> > So I think that the word "denotes" to connect a
>> thesaurus-theoretic and
>> > a ontology-theoretic point of view is dangerous - as in logic
>> > and mathematics this usually signifies semantics - we are
>> not (should
>> > not) be saying that the class provides a semantics for the concept.
>>
>> Agreed.
>>
>> > An alternative term then?  skos:classifierFor is perhaps
>> most precise,
>> > though a bit awkward.  But I prefer it to the alternatives we have
>> > seen so far which imply some kind of semantic relationship.
>>
>> To me that also implies a semantic relationship but maybe
>> that's just me.
>>
>> > Nikki says:
>> >
>> >> Or is this debate really about the fact that we want to stick some
>> >> machinery capable of SKOS<->OWL stuff in SKOS-Core right
>> now, so that
>> >> SKOS-Core stands in its own right allowing us to tackle
>> SKOS-Mapping
>> >> separately?
>> >
>> >
>> > As far as I see - yes!  The use of this property is to do
>> the modelling
>> > task of relating SKOS and OWL - and SKOS-mapping should be separate.
>>
>> To me there's no particular difference between saying that two SKOS
>> Concepts are trying to model the same "real world" thing and
>> saying that a
>> SKOS Concept and an OWL Class are trying to model the same
>> "real world"
>> thing. So I'm with Nikki, it seems odd putting it in the core
>> rather than
>> in mapping.
>>
>> > To turn to the specifics of the proposal (to start a new
>> controversy),
>> > does it make sense (particularly when taking a point of view that
>> > we are providing a classifier for an RDF resource) for this property
>> > to be a functional property?  This would mean if two
>> resources have the
>> > same classifier, they can be identified.  This may not make sense.
>>
>> My vote would be "no".
>>
>> For example, you might have a SKOS Thesaurus concept
>> "my:Person" an RDF
>> Class foaf:Person and an RDF Class drc:Person. They are all
>> trying to model
>> the same real world notion but in different ways (e.g.
>> drc:Person might
>> have cardinality restrictions on properties that foaf:Person
>> has nothing to
>> do with). As I understand it, the point of this property is
>> to be able to
>> say "my:Person and foaf:Person are both attempts to model the
>> same thing"
>> without carrying any semantics such as cardinality restrictions.
>>
>> It would be reasonable to also want to say "my:Person and
>> drc:Person are
>> both attempts to model the same thing" without that implying that
>> drc:Person = foaf:Person (with all that would entail from the formal
>> semantics of the foaf and drc schemas).
>>
>> Cheers,
>> Dave
>>
>>
>



----------------------
NJ Rogers, Technical Researcher
(Semantic Web Applications Developer)
Institute for Learning and Research Technology (ILRT)
Email:nikki.rogers@bristol.ac.uk
Tel: +44(0)117 9287096 (Direct)
Tel: +44(0)117 9287193 (Office)

Received on Friday, 1 October 2004 11:35:36 UTC