Dear Sean,
Godfrey,
Matthew, Ian et al
STEP
makes a nice distinction between a property,
the representation
of the property
and the presentation
of the property
[MW] I agree. Both Ian and I have been involved in developing
parts of ISO 10303 (STEP)...
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).
[MW] Geometry is what STEP is good at. We (well David Leal if
truth be told) adapted the STEP geometry for use in ISO 15926.
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.
[MW] However, I do not recall ontology representation as being
within the scope of ISO 10303 J
Regards
Matthew
West
Information Junction
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.matthew-west.org.uk/
This email originates from Information Junction Ltd. Registered
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Registered office: 2 Brookside, Meadow Way, Letchworth Garden
City, Hertfordshire, SG6 3JE.
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
From:
ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Godfrey
Rust
Sent: 06 February 2009 07:56
To: [ontolog-forum]
Subject: Re: [ontolog-forum] RDF & RDFS (was... Is there something I
missed?)
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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
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.matthew-west.org.uk/
This email originates from Information Junction Ltd. Registered
in England and Wales No. 6632177.
Registered office: 2 Brookside, Meadow Way, Letchworth Garden
City, Hertfordshire, SG6 3JE.
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