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Excellent, Charles! You are elected.
Peter, what are the mechanics for wiki capture of this
topic?
Thanks much,
Leo
_____________________________________________
Dr. Leo
Obrst The MITRE Corporation, Information
Semantics
lobrst@xxxxxxxxx Center for Innovative
Computing & Informatics
Voice: 703-983-6770 7515 Colshire
Drive, M/S H305
Fax: 703-983-1379 McLean, VA
22102-7508, USA
Leo, I would like to volunteer to capture all of the notes
concerning the "Dimensions/Aspects" of ontology types. For now,
I'll leave the "Logical Theory(?)" topic to someone else . . . The
topic interests me a great deal, and as I've already contributed at least two
potential dimensions to the conversation, I would like to see it continue and
be recorded. Chuck
Charles Turnitsa Project Scientist Virginia Modeling, Analysis & Simulation Center Old Dominion University Research Foundation 7000 College Drive Suffolk, Virginia 23435 (757) 638-6315 (voice) (757) 686-6214 (fax) cturnits@xxxxxxx
-----ontology-summit-bounces@xxxxxxxxxxxxxxxx wrote:
-----
To:
<gruninger@xxxxxxxxxxxxxxx>, "Ontology Summit 2007 Forum"
<ontology-summit@xxxxxxxxxxxxxxxx>
From: "Obrst, Leo J."
<lobrst@xxxxxxxxx>
Sent by:
ontology-summit-bounces@xxxxxxxxxxxxxxxx
Date: 28/01/2007
06:41PM
Subject: Re: [ontology-summit] dimensions/aspects of ontology
types?
I think we need to capture these
notions in the wiki. It will be
difficult but, I hope, possible.
Peter, what do we need to do to accomplish the above?
Because
we are at the (relative) beginning of our discussion, I'd like
to ask for
topic volunteers who would capture our evolving notions
about these
notions. Note that they can be just quick notes and
extractions from
emails now. These may evolve toward coherent notes,
form the bases of
potential statements eventually: who knows?
Unfortunately, email doesn't
capture discourse.
Thanks,
Leo
ps. Any volunteers? Maybe by
topic? Ontology as logical theory.
Dimensions/aspects of ontology types?
There will be more; in fact,
propose others.
Expressiveness and
complexity of modeling language vs. complexity of
computation performed
on content in that language?
_____________________________________________
Dr. Leo Obrst
The MITRE Corporation, Information Semantics
lobrst@xxxxxxxxx Center for Innovative Computing &
Informatics
Voice: 703-983-6770 7515 Colshire Drive, M/S H305
Fax:
703-983-1379 McLean, VA 22102-7508, USA
-----Original Message-----
From:
ontology-summit-bounces@xxxxxxxxxxxxxxxx
[mailto:ontology-summit-bounces@xxxxxxxxxxxxxxxx]
On Behalf Of Michael
Gruninger
Sent: Sunday, January 28, 2007 6:25
PM
To: Ontology Summit 2007 Forum
Subject: Re: [ontology-summit]
dimensions/aspects of ontology types?
Hi Bill,
Quoting Bill
Andersen <andersen@xxxxxxxxxxxxxxxxx>:
> Hi
Leo...
>
> I have some comments about some of these proposed
dimensions..
>
> On Jan 28, 2007, at 14:40 , Obrst, Leo J.
wrote:
>
> > Dimensions of Ontology Types:
>
>
> > 1) Formality: Informal (Formality = 0) vs. Formal
(Formality = 1)
>
> I don't quite get what this means. If
we're not talking about
> artifacts that are somehow used to influence
software to do things we
> want, I don't see the point. So, for
some thing O, if Formal(O)
> means that O is a logical theory, then,
following ChrisM, I don't see
> what anything not formal should even
be considered, since otherwise,
> it would be pretty close to
impossible to say how it could be used
> for some computational
end.
The ecumenical definition of "ontology" that Mike Uschold
and I have
used is:
"An ontology includes a vocabulary of terms
together with a
specification of
the intended meaning of the
terms."
Different approaches to ontologies are distinguished by the
latter
condition,
that is, in the way that they specify the intended
meanings.
Leo is pointing to a basic partitioning of these
approaches.
A formal ontology is a set of sentences in a language
that has a model
theory,
that is, a notion of interpretation that
supports truth assignments,
satisfiability,
and entailment.
(As
observed by recent discussions, this is a necessary but
not
sufficient
condition,
since there are sets of sentences that
not everyone would consider to
be an
ontology,
but this is not my
point here).
On the other hand, the specification of intended
meanings in an
informal
ontology relies on
extralogical mechanisms
(natural language, diagrams, canonical
software
implementations).
The line does become a little blurry
when the expressiveness of the
underlying
logical language
for an
ontology is insufficient to axiomatize the intended
interpretations
of
the terms.
For example, in OWL-S (the OWL ontology for web
services), different
classes of
processes
such as
Unordered,Sequence,etc are axiomatized in OWL.
Nevertheless, OWL is not
expressive enough to capture the full intended
interpretations
of
these classes, which is specified in natural language
as
documentation.
>
> > 2) Expressivity: Expressivity
of the semantic model (i.e.,
underlying
> > knowledge
>
> representation language or logic) [No scale determined
yet]
>
> This is a property of a logical system, independent of
the instances
> of which we wish to regard as "ontology", so I'd
exclude this
dimension.
It is a property of a class of structures
AND the logical language.
There are classes of structures that are not
first-order definable,
and classes of structures that are not definable
in DL.
This is an important issue because we need to be able to
determine
whether the intended interpretations of the terms in the
ontology
can be defined within the advertised formal language.
-
michael
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