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John and Brand,
John's and Alan's statements are not without controversy and should not be accepted without disputation however we might be disposed to accept them because they align with our desires.
Upper and middle ontologies become increasingly important when you need to link or align domain ontologies. Why? Because you need to semantically bridge them and in the limit the bridging or integration mapping becomes a distinct integrative ontology in its own right. The more you integrate disparate domaan ontologies, the more you are driven to create these upward evolving intregrative ontologies. So the more you understand that you need higher levels of abstraction of semantics to "cover" or span the multiple domains. Hence the more you understand the need for common middle and upper ontologies. And note this is a bottom up rather than a top down argument.
Despite your inclinations or predispositions, this program is forced upon you.
I know a lot of the current hype about the Semantic Web pushes the (good) idea about islands of local semantics. But the problem of linking those islands, ie creating peninsulas of semantics or eventually continents does not just happen easily. When you understand that (and largely because you've experienced it many times by developing domain ontologies and needing eventually to link them), you understand not just the preferance but the need for common situating semantics, common upper and middle ontologies.
Nearly everone these days believes in non-monolithicity of ontologies, hence embraces a "lattice of theories" notion of logically (and systematically logically) related ontologies. So ONE UBER ONTOLOGY is not necessarily the case (it's still a possibility, mind you, and can't be ruled out but instead empirically determined). However, just like the rest of science, these things must be determined without prejudice, ideology, and influence by desired expectation.
Thanks, Leo
Dr. Leo Obrst - MITRE - Information Semantics - lobrst@xxxxxxxxx
-----Original Message-----
From: ontac-forum-bounces@xxxxxxxxxxxxxx <ontac-forum-bounces@xxxxxxxxxxxxxx>
To: Niemann.Brand@xxxxxxxxxxxxxxx <Niemann.Brand@xxxxxxxxxxxxxxx>
CC: ONTAC-WG General Discussion <ontac-forum@xxxxxxxxxxxxxx>
Sent: Sun May 14 17:31:26 2006
Subject: Re: [ontac-forum] Problems of ontology
Brand,
I'm glad that you liked the comments.
> Thank you for your succinct conclusion.
But I would also like to emphasize that I believe
research on ontology is important. And I would
mention Cyc as an example of a very large system
that does have an upper ontology. But the director,
Doug Lenat, has made the following points:
1. The upper ontology is the *least* important part.
2. The middle-levels of the ontology contain the most
heavily used concepts.
3. And for any particular problem or task, most of the
detailed reasoning is done at the lowest level of
_microtheories_, of which there were 6,000 in 2004.
These three points, together with other studies, such
as Alan Bundy's paper or my paper on knowledge soup,
indicate that the most important work on making
systems interoperate depends on the categories and
axioms at the lower levels, not the upper levels.
Bundy also made the point that most private companies
and many government agencies consider their ontologies
to be trade secrets or confidential material that they
have no intention of divulging or sharing with anybody
else. That provides further incentive to focus on the
methods that address task-oriented revisions, rather
than global alignments.
In my previous note, I included the introduction to
Bundy's paper. Following is the conclusion.
John
_______________________________________________________
Conclusion
We have argued that representation is a fluent in commonsense
reasoning, and that repairs to and evolution of representation
is an everyday event. If intelligent agents are to conduct
commonsense reasoning, it will be necessary to build automated
reasoning systems in which the representation can evolve
dynamically in reaction to unexpected failures and successes
of reasoning, and to other triggers yet to be explored. In
particular, such functionality will be an essential ingredient
in interacting, peer-to-peer multi-agent systems, such as are
envisaged in the Semantic Web. Agents will need to be able
to cope dynamically with minor variations between their
ontologies.
We have initiated research into automatic dynamic ontology
evolution. The ORS system operates in a planning domain
over KIF ontologies, where failures in plan execution
trigger repairs to the planning agent's ontology. Despite
the simplifying assumptions and limited functionality of this
prototype system, it can account for over a third of the
ontological mismatches between different versions of several
popular and widely used ontologies. More details about this
work can be found in (McNeill 2005).
Further work is clearly required to lift the current limitations
of this work: removing the simplifying assumptions about
agents; extending it to other kinds of ontology such as those
based on description logics; extending the kinds of mismatch
and repair triggers it can deal with; applying it to non-
planning domains; and implementing it within a fully
peer-to-peer architecture, in which all agents are forming
plans and repairing their ontologies. We are currently engaged
on this further work within the EU Open Knowledge Project.
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