Mark Waser wrote:
Richard, is this correct? Are human-engineered airplanes complex in
the sense you mean?
Generally speaking, no, not in a substantial enough way.
Which means that there is a certain amount of unpredictability in some
details, and there are empirical factors that you need to use (tables
of lift coefficients, etc.), but beyond these empirical factors there
is little impact of the complexity.
Richard, you're obviously not familiar with high-speed aerodynamics.
There is not "a certain amount of unpredictability". It is out-and-out
virtually unconstrained chaos. There are *no* nice little tables of
lift coefficients. A human being cannot operate an F-14 by themselves.
A computer cannot operate an F-14 unless it is receiving sub-millisecond
updates because the behavior is too chaotic to predict. Yet, like
everything else in nature, this seeming chaos is the result of a
relatively small number of relatively simple rules (and a huge butterfly
effect). An F-14 in flight makes "a system in which all the components
are interacting with memory, development, nonlinearity, etc etc etc."
look nearly trivial because virtually *anything* can effect it
(temperature thermoclines, radiant heat differences because of changes
in the land below, wind speed, clouds, even the passage of migratory
birds) -- yet the behavior is entirely bounded enough for a fast
reacting computer to manage it.
How is this not complex (according to your definition)?
Remember that the strict definition of "complexity" asks whether a
theory can be found to predict the overall behavior.
In this case, the engineers DO have a theory, because they were able to
build a flight control computer to make sensible adaptations to overcome
the instability of the system. If they did not have such a theory, they
would not have been able to write any flight control software at all.
The system does indeed have some complexity in it (all systems do,
remember), but the engineers found enough predictability in the system
that they were able to write the control software and treat the
complexity as a noise signal that had to be compensated for. So at the
most important level of description, the system is not complex.
My point is that to be able to make the plane fly straight, the
engineers did not have to second-guess anything complex .... they did
not have to make any predictions about whether a particular bit of the
plane was going to exhibit [Behavior A], they just had to wait to see
which behavior was going to turn up, then make the appropriate reaction
to it (and the engineers know what the "appropriate" reaction is, of
course). The engineers are not second-guessing the complexity, they are
factoring it out. They are making it irrelevant by simply compensating
for it. They are turning it into a noise signal.
So the plane's behavior does not "depend" on the complexity in any way,
because the whole point of the flight control computer is to watch the
complex behavior like crazy (several times a millisecond, as you say)
and simply counteract it.
The fact that they were able to counteract the instability tells us that
there was a lot about the plane's dynamics that was extremely
predictable (or else no rational compensation software would have been
possible).
And once the system has been built with [complex-behaving plane] PLUS
[complexity-cancelling software], the result is an overall system that
is not complex.
Is the math underlying the F-14 untouchable? No: there is enough
regular math to enable the engineers to write that flight control
software. Looking at the math AT THAT LEVEL OF DESCRIPTION, we would
never have predicted that this system was complex: we would have
predicted some instability caused by a complex component, but the rest
of the math would have caused us to predict that the system would not be
complex as a whole. So, this system is consistent with my observation
that untouchable math begets complexity, and that touchable math is
consistent with non-complexity.
One last note: remember that we have to look at the system as a whole.
We can always dip down into a system and find some complexity, but
that would be to change the terms of reference.
Richard Loosemore
Stepping back to the intelligent systems context: you cannot pull this
trick of compensating for the complexity in an AGI. There is simply no
analogy between these two systems. Build an intelligent system in which
something cancels out all the annoying influence of the symbols, with
their complex interactions, so that all of that symbol-stuff can be
treated as noise and the system as a whole becomes non-complex? Makes
no sense. The symbols and their interactions are the very core of the
system's intelligence. You cannot factor them out.
-------------------------------------------
agi
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