Derek Zahn wrote:
Mark Waser:
> I don't know what is going to be more complex than a
variable-geometry-wing
> aircraft like a F-14 Tomcat. Literally nothing can predict it's
aerodynamic behavior.
> The avionics are purely reactive because it's future behavior cannot
be predicted
> to any certainty even at computer speeds -- yet it's behavior
envelope is small
> enough to be safe, provided you do have computer speeds (though no human
> can fly it unaided).
I agree that this is a very sensible way to think about being "complex"
and it is certainly similar to the way I think about it myself. My
embryonic understanding of Richard's argument suggests to me that he
means something else, though. If not, traditional engineering methods
are often pretty good at taming complexity as long as they take the
range of possible system states into account (which is what you have
been saying all along).
Since I'm trying (with limited success) to understand his point of view,
I might suggest that (from the point of view of his argument), the
global regularities of the aircraft (its flight characteristics) DO have
a sufficiently-efficacious small theory in terms of the components (the
aircraft body, including the moveable bits). In fact, it is exactly
that small theory which is embedded in the control program. Since the
global regularities (straight-line flight, turns, and so on) are
sufficiently predictable from the local interactions of the control
surfaces with the air, the aircraft is not complex *in the sense that
Richard is talking about*.
Now I suppose I've pissed everybody off, but I'm really just trying to
understand Richard's definitions so I can follow his argument.
I read this after replying to Mark's later comment.
You have summarized exactly what I said there.
It is most important that, when answering these questions about whether
or not system X is complex, we keep in mind that we have to choose our
level of descriotion and then stick to it.
So in this case the system as a whole is not complex. A component of it
is complex (though not in a very demanding way, compared with many
complex systems), but if we accidentally slip from discussion of one to
discussion of the other, things do get confused.
So Mark is right to see complexity, but that is one level down.
Richard Loosemore
-------------------------------------------
agi
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