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Godfrey, Matthew, Ian et al
STEP makes a nice distinction between a
property, the representation of the
property and the presentation of the
property
For example, in mechanical CAD a physical part has a property =
"shape" which has a representation = "surface model" which
may be shown on a display as presentation="shaded
image".
It may also have property="shape",
representation="Constructive Solid Geometry" and
presentation="edges"
Further, the same representations also be used for
other properties such as the envelope for a mechanism, or the cavity
inside a part (useful for modelling flow though a jet
engine).
We could therefore say that an *ontology is a property
of a (view of) universe of discourse ;-)
; RDF can be used as
a representation of the *ontology, and XML as a presentation of that
representation.
Notes:
1) I use *ontology to indicate Ian's real world
meaning, as opposed to ontology meaning a formal system, the preferred usage in
this forum.
2) I am using "property" in the STEP sense - "a move in
a language game, which allows one to talk about a
thing having properties such as shape, material, cost, duration, etc, without
admitting these things are subclasses of a general class called
'property'"
3) No need to discuss what is in people's heads - ontologies are
manifest in behaviour, particularly processes dependent on classification, such
as asking the grocer for three red apples, he goes to the draw marked apples.
etc
Sean Barker
Bristol, UK
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Matthew West wrote:
Talking about what is
in someone’s head just doesn’t cut it I’m afraid. It is at best a loose way of
talking. Where you have several things that have something in common, what you
do have is an abstraction, and my extensional analysis would make that a
class. So if I have 5 copies of the same content, there is a class that
represents the pattern that is common to those 5 files. And if I have the
“same” ontology that is represented in different languages, then there
is a class that represents that
sameness.
This is consistent with the analysis that is
generally used in music, book and journal publishing metadata standards
such as ONIX and DDEX, and the widely adopted bibliographic FRBR
analysis, of an "abstraction" or "abstract work" with any
number of "manifestations". It may apply to the play "Hamlet" or the
song "Yesterday", which retain a unique perceived identity but may
be expressed in a wide variety of manifestations in different genres,
languages and so on, and it may apply as well to an ontology or computer
program. As Matthew points out, these function (and very usefully) as
abstract classes representing common content: the entire network of music
copyright collection societies operates to collect money for the use of just
such abstractions.
The elusive problem of identity remains, however.
The decision about whether a particular manifestation really is the song
"Yesterday" or just something that sounds a bit like it is something which
exists in someone's head and, in the content industries, is ultimately settled
where necessary in a court of a law using reasonable but ultimately
arbitrary criteria (such as musicological analysis). Identity between the
underlying abstractions of two ontologies is in general
more testable.
Godfrey Rust
Chief Data
Architect
Rightscom/Ontologyx
Linton House LG01
164/180 Union Street,
London SE1 0LH
www.rightscom.com
Direct +20 8579
8655
Rightscom Office +20 7620 4433
Mobile 07967
963674
----- Original Message -----
Sent: Friday, February 06, 2009 7:28
AM
Subject: Re: [ontolog-forum] RDF &
RDFS (was... Is there something I missed?)
Dear
Pat,
PS - I'm not sure about where this idea of a mental
model of an ontology
came from. I never mentioned it, and I certainly
don't have an ontology in
my head. Of course the ontology has to be
represented in some way - CL,
RDFS, OWL, UML, EXPRESS, arse-barcodes,
who cares ?
What is this thing that is in common between al these
different file formats? Where is it, if not in your head? This is
rather like the old chestnut of saying what exactly a program is, if you can
write the 'same' program in several wildly different programming languages.
For example, quicksort can be implemented in just about any programming
language, and its still quicksort. In CS we have the useful distinction
between algorithm and program, maybe we need a similar terminological
distinction for ontologies. Any suggestions?
[MW]
Ok. So is the quicksort program in your head the same as the quicksort
program in my head (I even remember writing one once in Basic)? Talking
about what is in someone’s head just doesn’t cut it I’m afraid. It is at
best a loose way of talking. Where you have several things that have
something in common, what you do have is an abstraction, and my extensional
analysis would make that a class. So if I have 5 copies of the same content,
there is a class that represents the pattern that is common to those 5
files. And if I have the “same” ontology that is represented in different
languages, then there is a class that represents that
sameness.
Regards
Matthew
West
Information
Junction
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