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RE: Indirection

From: Miles, AJ \(Alistair\) <A.J.Miles@rl.ac.uk>
Date: Fri, 4 Feb 2005 17:48:19 -0000
Message-ID: <F5839D944C66C049BDB45F4C1E3DF89D18DB78@exchange31.fed.cclrc.ac.uk>
To: "Dan Brickley" <danbri@w3.org>
Cc: <public-esw-thes@w3.org>

... And (having given this another 15 minutes of thoughts and a fag break) I am almost certain that, when the creators of a thesaurus include a descriptor such as 'People', they intend that term to denote *both* an abstract concept *and* a class of things which they believe to exist in 'the real world'.  Simililarly, when they include a descriptor such as 'Economic co-operation' they intend that term to denote both an abstract concept *and* a class of processes which they believe to be occurring in 'the real world'.  And again, a descriptor such as 'King Henry VIII' denotes *both* an abstract concept of a person that once lived, and the actual person they believe to have once existed. 

I reckon that thesaurus creators and users make no kind of metaphysical or existential divide between the two layers of abstraction we are talking about.

And that means, if we are to faithfully model a thesaurus as a set of 'resources' (in the RDF sense), then each thesaurus 'resource' may have both a 'conceptual' and a 'real' aspect.

Then the role of SKOS Core becomes to allow you to make statements about the 'conceptual aspect' of a resource, without excluding the possibility that the same resource also has a 'real' or 'concrete' aspect.

I'm thinking that it is both unreasonable and impractical to ask a user of a thesaurus to use one set of URIs to denote the 'conceptual' entities, and another set to denote the 'real' ones (although I'm sure there will be situations where this is desirable, but I expect them to be very much in the minority).

That's it for the moment.

Cheers,

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 Miles, AJ 
> (Alistair)
> Sent: 04 February 2005 16:53
> To: Dan Brickley
> Cc: public-esw-thes@w3.org
> Subject: RE: Indirection
> 
> 
> 
> .. And another thing - Dan you use wordnet nouns as classes.  
> Isn't that folding the layers of indirection?
> 
> Cheers,
> 
> 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 Miles, AJ 
> > (Alistair)
> > Sent: 04 February 2005 16:45
> > To: Dan Brickley
> > Cc: public-esw-thes@w3.org
> > Subject: Indirection
> > 
> > 
> > 
> > Hi Dan, playing devil's advocate ...
> > 
> > > [[
> > > SKOS Core is an extension of the RDF model [ref], which is 
> > in turn an
> > > extension of the graph data model [ref]. For an 
> explanation of these
> > > concepts, please refer to [ref]. The reader of this guide 
> > > should have at
> > > least a basic understanding of the RDF model and the graph 
> > data model.
> > > ]]
> > > 
> > > This needs a little rewrite. The term 'RDF model' is 
> unfashionable, 
> > > post-RDFCore. It used to mean, roughtly, 'graph data model', but 
> > > now evokes Model Theory etc. SKOS isn't a 'semantic 
> > extension' to the 
> > > RDF model theory; this wording could give the impression it is. 
> > 
> > Why can't SKOS Core be a 'semantic extension' to the RDF 
> model theory?
> > 
> > > It can be useful to
> > > understand the subtle, layered relationship between SKOS and RDF, 
> > > particularly when building applications that combine SKOS 
> data with
> > > other information modeled using RDF.
> > 
> > Your gonna hate me, but ... 
> > 
> > > This is the SKOS approach. Technically, it creates an extra 
> > > layer of indirection, so that from the RDF point of view we are 
> > > describing things such as 'The concept of Economic 
> > > integration', rather 
> > > than <em>Economic integration<em> itself. 
> > 
> > ... what's the difference?
> > 
> > Seriously, if I say ...
> > 
> > ex:A a skos:Concept.
> > ex:B a rdfs:Class.
> > 
> > ... what fundamental commitments have I made about the 
> > natures of ex:A and ex:B?
> > 
> > And what if I say ...
> > 
> > ex:C a skos:Concept; a rdfs:Class.
> > 
> > ... which inevitably will happen.  What does that mean?
> > 
> > ***We need an answer on whether skos:Concept and rdfs:Class 
> > should be disjoint.***
> > 
> > If we don't make an explicit statement about this, they will 
> > be used as if they are not disjoint. 
> > 
> > And if we believe they should be disjoint, we need to be able 
> > to explain exactly what you gain by keeping them disjoint.
> > 
> > The 'two levels of abstraction' explanation is hard to grasp. 
> >  If we want to enforce two levels of abstraction, we're going 
> > to have to explain ourselves *extremely* well, and we're 
> > going to have to dangle a bloody big carrot.
> > 
> > Or have I just asked, 'can a person ever get out of their own head?'
> > 
> > Taoists need not respond :)
> > 
> > Al.
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> 
Received on Friday, 4 February 2005 17:48:52 GMT

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