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What isn't a Concept?

From: David Menendez <zednenem@psualum.com>
Date: Thu, 01 Apr 2004 00:42:11 -0500
To: public-esw-thes@w3.org
Message-id: <r02000200-1033-52E4368E839F11D8A9E7000393758032@[10.0.1.5]>

My apologies if this has been discussed to death already; I just
recently learned of SKOS.

After reading the draft specs and some of the recent discussion on this
list, I'm still not sure what things count as a skos:Concept,
particularly as it pertains to the use of foaf:topic and dc:subject.

Lets say I have a scheme with these elements:

  _:A a skos:Concept
    ; skos:prefLabel "Politicians"
    .
  
  _:B a skos:Concept
    ; skos:prefLabel "U.S. Presidents"
    ; skos:broaderGeneric _:A
    .
  
  _:C a skos:Concept
    ; skos:prefLabel "George Washington"
    ; skos:broaderInstantive _:B
    .

Now, _:A and _:B I can handle, but I'm not sure about _:C. Is that the
sort of thing one would include in a thesaurus? (I'm guessing it is, by
analogy with the "Red Lion pub" example in sec. 3.9.2, but I could be
wrong.

Let's also say I have a description of George Washington, like so:

  _:D a foaf:Person
    ; foaf:name "George Washington"
    .


Do _:C and _:D denote the same resource? If not, what is the
relationship between them? If they are the same, then what is the
difference between skos:Concept and rdf:Resource?


This seems to be connected to the issue of foaf:topic vs. dc:subject.
Consider these statements:

  _:E dc:subject _:C.
  _:F foaf:topic _:D.
  _:G foaf:topic _:C.
  _:H dc:subject _:D.

If we interpret _:C as a subject code which stands for George
Washington, rather than George Washington himself, then we could
interpret this as asserting that _:E and _:F are about George Washington
and _:G is about the subject code for George Washington (the statement
about _:H is inconsistent with the sense of dc:subject).

If _:C denotes George Washington, then _:F and _:G are about George
Washington and the assertions about _:E and _:H are inconsistent with
dc:subject.

If dc:subject and foaf:topic can be used interchangably, then we'd have
to interpret it as saying _:E, _:F, _:G, and _:H are all about George
Washington.


Anyway, this is where I start feeling like I must be missing something.
Am I totally on the wrong track here?

(PS. I'm not currently on the list, so please include me in replies.
Thanks.)
-- 
David Menendez <zednenem@psualum.com> <http://www.eyrie.org/~zednenem/>
Received on Thursday, 1 April 2004 00:42:36 GMT

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