ONT Re: SUO: 21 May 2002 -- Unanswered Questions About SUMO Set Theory
At 07:31 AM 6/2/2002 -0700, Erik Larson wrote:
That is my lead-in to ontology
considerations: build ontologies with solutions to problems in mind! If
you already have an 'Ontology', reformulate it to cover a set of
solutions important to your customers (or to facilitate a set of apps you
have or want to build).
Practically speaking, this will mean at least two things:
1. Upper Ontology concepts are necessary (e.g., for partitioning
categories of things: keeping disjoint categories disjoint, etc), but
it's silly to spend a lot of effort writing axioms for high-level terms,
since the rules will almost always have consequences that no one cares
about, and even if they might in some cases, it's not as if you'll know
what this value will be beforehand, and be able to pre-empt the process
by making your terms and rules "up front." Also the terms
themselves will tend to change as different inference requirements
change. Even if you can define a bunch of 'context' theories and cram
terms into them to preserve local consistency, truth,relevance, etc, the
way the contexts themselves have been chosen will also need to change as
different problems are posed. This suggests a minimalist approach to
upper ontological terms (for that matter, of ontologies generally)--the
less "bloat" you can get by with, the better.
Hi Erik:
Your points here have given me a lot of pause for thought. I think
that I disagree a little bit with your ontology heuristics, here but let
me try to get clearer on what you're claiming here and also try to give
some general indication of why I think I might disagree.
Regarding your point in (1), I'd like you to provide a bit more argument
or clarification here. If we think that a concept is important enough to
include in our upper ontology, why assume that its meaning isn't relevant
enough to bother to attempt to further articulate with axioms? You seem
to have acknowledged that subtyping and disjointness rules are important
for upper ontology concepts. How do you jump from
the acknowledgement that the conclusions from subtyping and disjointness
rules will be entirely germane to our applications to the assumption that
rules that articulate any other kind of information are, as a default
rule, useless? This isn't obvious to me.
2. Large chunks of ontological terms won't be
reusable from domain to domain, because they must be choosen to fit with
axioms that are written to get a set of specific derived consequences for
end-users. This will naturally tend to make a vocabulary more specific to
its uses. I've seen how this happens first-hand, in a prior engineering
project where our team had, ostensibly, lots of concepts already asserted
in the KB on our topic for us to use. Once we clearly understood the
problem-space however, it was obvious that we had to ignore large chunks
of the pre-existing terms to make any progress. Even when we could
partially salvage existing knowledge, it had to be re-written in a way
that would facilitate the specific needs of our project, and this took
practically as much time as creating everything afresh. (True, some of
the upper ontology terms were more reusable, but also less relevant).
I'm not quite sure that I understand the first two sentences in section
2. Regarding re-use, of course, you're correct that there is a lot of
different knowledge that will be germane to a domain and we shouldn't
assume that rules written for one facet of the domain will be reusable
for reasoning about another facet of the domain. If you give me a set of
rules designed to reason about automobile purchasing it's possible that
it may not be very useful for reasoning about automobile repair. I may
have to write new rules for reasoning about automobile repair. This
claims seems to be true and noncontroversial but is there more to it than
this?
In short (well, I guess I should say "in
long" now), IMHO don't bother writing rules that just 'express
knowledge', and don't bother creating (too many) terms with just that
motivation either--at least not if you want to solve problems for Real
People.
What is an upper ontology but something that "just expresses
knowledge"? Are you claiming that it is useful to write
some rules that just express knowledge and not others? Why is it
useful to have subtyping and disjointness rules, rules which certainly
seem to just express knowledge, but no other rules?
Or do you actually have a more radical view? Do you think that each
application is so different from each other one that trying to find some
subsuming body of useful knowledge, an upper ontology, is
pointless? I disagree with this claim, just for the record, but I'd
like to hear more before trying to persuade you if it is your own
view. (I'm more sympathetic to the claim that an upper
ontology should be quite small but very well axiomatized. Part of
the reason I'd be more sympathetic is because it's conceivable that human
intelligence is like this, i.e., based on a relatively small number of
very well understood concepts. It's hard, however, to imagine
generating anything resembling intelligence, i.e., an ability to generate
solutions to problems, if a system has very little understanding of *any*
upper ontology concept.)
By the way, please tell me who these Real People are and please let
me now how I can attain such enhanced metaphysical status if I don't
already have it.
best,
Mike Pool
-Erik
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Mike Pool
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