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Re: the question - does the upper ontology matter
much?
My recollection from talking to Doug Lenat is that when he
says that the upper ontology is not the most important part
-
he means that several different upper ontologies might
serve equally well, and there is no requirement for one specific upper
ontology.
*** But, BUT, BUT!!!!! ***
If any two ontology-driven systems want to work together,
that upper ontology, WHATEVER IT IS, has to be the same.
I think Cathy's example of 'person' is a good illustration
of why. If a system decides to change its upper ontology on the fly, it
should be prepared for serious chaos.
So let us not confuse the issue by failing to recognize the
distinction between one group choosing an upper ontology (or no upper ontology)
for its own isolated purposes, and multiple groups choosing an upper ontology
for communication between semantic systems. These are very different
application scenarios, having different requirements. The upper ontology
has an additional function in providing the "common sense" implicit knowledge
that people need to fall back on more general principles when the specialized
knowledge and pre-existing experience are insufficient to solve a problem -- but
the ONTACWG deliberations have not reached the implementation level where that
function is of direct concern.
Since the ONTACWG is focused mainly on semantic
interoperability, the questions of whether different upper ontologies can
function together **in an interoperability scenario** should not be ignored or
conflated with a system operating independently to solve some
problem.
The AI community discovered a long time ago that most of
the reasoning people do about practical problems depends heavily on specialized
knowledge of the domain of interest. That has been confirmed many times,
and a recent example would be the Halo project. But these
domain-specific pilots invariably involve systems operating independently,
not systems trying to **interoperate** semantically. In our discussions I
hope we can keep these very important distinctions right at the forefront, since
if they are ignored it will lead to unnecessary confusion about
the role of the upper ontology.
Pat
Patrick Cassidy
MITRE Corporation
260 Industrial
Way
Eatontown, NJ 07724
Mail Stop: MNJE
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Email:
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First of all, apologies to all for
the unfortunate header on my previous message – I’m a bit out of practice
posting to lists like these, and I’m receiving this list in digest form (which
actually I’m finding a bit confusing, I might change
that).
Thanks, Chris, for the reminder
about CL, with which I’m familiar. Following Leo – yes, what was concerning me
was issues of inference engine design qua changeable arities. It just sounded
to me like a recipe for chaos (just imagining the kind of backchaining that
might result….!!!) The suggestion was made that Bundy was envisaging a system
involving a metalevel of reasoning whereby changes to the formalism itself
would be applied at that level following some independent set of heuristics. I
wouldn’t want to rule that out in principle but would love to hear some actual
details of rules which might be applied at that level.
There was a post by Barry Smith
which I would’ve liked to read but it got scrubbed in my digest due (I think)
to being in HTML – I don’t suppose it could be
re-posted?
John I was interested to read your
description of your evolution away from advocating axiom-rich ontologising
towards recommending something much closer to Wordnet, indeed a system where
(if I have it right) the only assertions in the ontology are purely
definitional, concerning the meanings of terms, and no empirical claims are
made. This sounds prima facie plausible. However, can a sharp distinction be
made between these two categories of claim? I don’t think so. I think that is
one of the lessons of Peirce’s pragmatism. Consider for instance, “Electrons
have a negative charge”. This was an empirical claim at some early stage of
atomic theory yet is now analytically true. “Cats have whiskers” – empirical
or definitional?
Also, when you say that assertions
in any upper ontology are “much less important” than assertions in
lower-middle and domain ontologies I think that this statement equivocates
dangerously on 2 different meanings of “Much less
important”:
i) Much fewer ontologist working
hours are spent on this part of the ontology
(true)
ii) Removing or changing
these assertions breaks or changes less (false!!)
I can remember quite a few times
when I was working at Cycorp that relatively minor changes made at the upper
level had (rather fascinatingly) unintended consequences for folks working on
specific projects. (To give just one example, ‘person’ (the legal – social
entity) was separated out from ‘human being’ (the species) and various
inferences which depended on those two concepts being munged together then
broke….)
Cheers,
Cathy
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