Re: [ontolog-forum] Ontology similarity and accurate communication

[Pat Hayes <phayes@xxxxxxx>]

At 8:00 AM -0500 3/6/08, Patrick Cassidy wrote:

> In the discussion on
> "orthogonal", Ed Barkmeyer pointed out:
>
> > My position is that two agents don't need to have
> non-overlapping
> > ontologies to be unable to communicate effectively.  Their
> ontologies
> > can have a 90% overlap, but if there is one critical idea that
> one has
> > and the other does not understand, they can't do business.
> >
>
>  Ed focused on the problem that arises when one 'critical idea'
> differs
> between the ontologies (or assumptions) of two different
> communicating
> agents.  I suspect that the problem can also arise when even
> minor
> differences are present in the interpretations of communicated
> information,
> because the interpretation of many concepts involve a very large
> number of
> implications and associated inferences.
>
>    This question appears to me to be one that is worthy of a
> separate field
> of investigation: precisely how different can ontologies be while
> sustaining
> an adequate level of accuracy in interpreting communications that rely
> on
> the ontologies?
>
>   My own suspicion is that the similarity **in the fundamental
> concepts**
> has to be very close to 100%.

There is quite convincing evidence that this is NOT the case. In particular, human beings seem to communicate adequately even while the terms they use in the communication are based on different mental ontologies. This happens so often that it seems to be the norm rather than the exception; it is part of what makes it so hard for reasonable people to come to agreement on basic ontological questions (such as whether time is a dimension or not).

>  The reasoning is something like
> this:  if the
> brain (or a simulation) does as much computation as one of our
> laptops, then
> it can run at least 1 million inferences per second.

There is no evidence whatever that the brain is capable of this. In fact, there near-conclusive evidence that the human brain is incapable of quite simple logical inferences without external support (such as drawing a diagram or writing a formula). In particular, people - even with logical training - consistently make systematic errors when given simple modus tollens reasoning tasks, with confidences in the 90% range.

> If (crudely
> calculating) the inferences supported by the differing ontologies
> differ by
> 1 in 1000 then two different ontologies will generate 1000
> differing
> inferences per second from the same information.  How much
> difference can be
> tolerated before something goes badly wrong - perhaps a direct
> logical
> contradiction?  My guess is that each serious "fact"
> that we rely on to
> support our everyday activities is supported by at least 1000
> assumptions,
> and getting one in a thousand wrong would invalidate the meaning of
> these
> facts, making normal actions, expecting predictable results,
> effectively
> impossible at any level.  A similarity of 99.9% in two different
> fundamental
> ontologies may not be enough for any meaningful level of
> communication.

Look, this HAS to be nonsensical. If this really were true, how could human beings EVER succeed in communicating? There is no way you and I could come to a logically secure agreement on 1000 axioms even if we had months to do it in and had nothing else to do. But children learn natural language at a rate of around 20 new words per day around the ages of 4-6 years old, pretty much all by themselves.

> But, as I said at the start, this is an
> issue that needs investigation.
>
>    We all know that people differ in assumptions and
> beliefs, and yet we do
> manage to communicate reasonably well in most cases.  How can
> that be?

Because the assumptions and beliefs themselves are irrelevant to the communication: all that matters is that we come to agreement on the beliefs we EXPRESS to one another.

> Well, it happens probably because we
> **know** that we have different
> assumptions and beliefs, and when communicating, only assume that
> there is a
> certain fundamental set of knowledge in
> common, and only rely on that basic
> set of common assumptions and beliefs to express the ideas we want
> to
> communicate.

No, that doesn't work. First, people don't know this. Second, how is agreement on this vital common 'core' achieved?

>  If we 'misunderestimate' what our
> fellow conversant knows,
> there can be and often is a miscommunication.  The ability to
> communicate
> effectively depends on the ability to guess correctly what facts,
> assumptions, and beliefs are likely to be shared by those with whom
> we
> communicate.  Among specialists, of course, a lot more common
> technical
> knowledge is assumed.
>
>    An issue that has occupied some of my attention lately
> has been the
> question of what basic ontological concepts are sufficient to
> support
> accurate communication.  I frame the issue as being analogous to
> the
> "defining vocabulary" used by some dictionaries as a
> controlled vocabulary
> with which they define all of their words.  For the Longman's, it
> is around
> 2000 words.  The analogous question is how many fundamental
> ontological
> elements (types/classes, and relations/functions) are needed to
> logically
> specify the meanings of all other terms used in a reasonably complex
> domain
> (having perhaps 100,000+ terms), to some adequate level of
> detail?

Define "define". If you mean logically define, then the number of defining terms is going to be comparable to the total number of terms. All 'natural kind' terms, for example, are definitionally primitive.

Most ontology languages don't even support definitions. Why are you so focused on definitions which usually don't, and often can't, exist? And which if they did exist would be largely functionally irrelevant in any case?

>  I don't
> know, but I think that this is a question that is important enough
> to
> warrant substantial effort.  My guess is in the 6,000-10,000
> concept range,
> and that many of those are fundamental enough to be common to many
> complex
> domains.
>   Any other guesses?

See above. My guess is that most terms we use, both the communicate with and to speak with, have no definitions and do not need them. We eliminated definitions from KIF because they caused only harm and provided no functionality.

Pat Hayes

>
> Patrick Cassidy
> MICRA, Inc.
> 908-561-3416
> cell: 908-565-4053
> cassidy@xxxxxxxxx
>
>
>  
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