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RE: Close to final draft of "classes as values" note

From: McBride, Brian <brian.mcbride@hp.com>
Date: Thu, 13 May 2004 12:24:52 +0100
Message-ID: <E864E95CB35C1C46B72FEA0626A2E808031A9343@0-mail-br1.hpl.hp.com>
To: Natasha Noy <noy@SMI.Stanford.EDU>, swbp <public-swbp-wg@w3.org>

Taking my first look through this document.  Please forgive me if the
comments below have already been discussed.   

I note that rdf/xml-abbrev examples are not being served with the RDF
mimetype.  Is this fixable?

Approach 1 is described as being in Owl Full.  I looks to me like RDFS until
the extension to restrict the values of dc:subject is introduced.  That
restriction doesn't seem to be about the main purpose of the note, i.e.
about defining subject hierarchies.  I suggest it might be useful to
separate out the RDFS solution and that Owl FULL solution, with separate
examples of each.

Approach 2 confuses me.  It seems to say that a LionSubject is of type lion,
which I interpret to mean it's the sort of individual with claws that I
don't want to meet close up when its hungry.  It doesn't seem intuitive to
me that the book "Lions: Life in the Pride" is about a particular individual
lion.  It seems to (an inexperienced and na´ve) me that the relation between
LionSubject and Lion should not be rdf:type.  Again, it seems to me that the
diagram of approach 2 is in RDFS.  Doesn't need Owl DL.

Approach 3:  There is presumably a relation between LionSubject and Lion.
Do we have any vocabulary to describe it?  Here we really need Owl to define
the transitive nature of the thesarus relations.

Approach 4 looks like we are back to RDFS.  Again, the Owl stuff is needed
for defining classes such as BookAboutLions, but that seems to me to be
beyond the point of the note - which I may be missing.  Do you really mean
that you are using a specific instance of the class as the value of the
dc:subject property, i.e. you have to give it a URI, or are you using a
b-node - in which case its inaccurate to say that you are using a member of
the class - you are using an existential variable.  Looking at the n3 code
for this approach, there is no dc:subject property on the examples so I
can't tell.  I assume you are using a bnode since otherwise, this would be
the same as approach 2.  If that is right, I believe the common convention
in the diagrams is to use the same elipse as for a named resource, and just
omit the name.

Approach 5 looks like a minor variation on approach 1.  Given that it
doesn't really let one take advantage of Owl DL reasoning, I'd suggest it be
presented as such, i.e. you can make approach 1 syntactically compatible
with Owl DL, but the cost of losing the subsumption reasoning.  In rare
cases this might be useful.

I don't have time to check more examples.  The one I have looked at seems
incomplete.  I wonder about separating ontology examples from instance
examples.

I also note that the example seems very close to the work of the thesaurus
task force.  I'm a bit nervous about this overlap.

When this document is described as nearly final, do we mean ready for wider
review, or do we mean final final?  Has it been reviewed by the DC folks?

Brian
Received on Thursday, 13 May 2004 08:30:14 UTC

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