Simple case of feedback without control

[Cliff Joslyn 931226, 10:35]

[Martin Taylor 931221 17:30]
(Rick Marken 931221.1330)

>So, is the bottom line that there is no simple, straight- forward
>way to describe a non-controlling negative feedback organization?

No. There is no simple straightforward way to make a quantitative
demonstration in a self-organized structure that I can think of at
the moment, and since such structures inherently demand a non-linear
effect somewhere along the line, all the problems of nonlinear
mathematics are likely to show up in any such system.

What about a convection cell in a heated fluid? Liquid at the bottom
is heated, it rises, it cools, it sinks. Heating causes rising, rising
causes cooling, cooling causes falling, falling causes heating.
Negative feedback. No control.

O----------------------------------------------------------------------------->

Cliff Joslyn, Cybernetician at Large, 327 Spring St #2 Portland ME 04102 USA
Systems Science, SUNY Binghamton NASA Goddard Space Flight Center
cjoslyn@bingsuns.cc.binghamton.edu joslyn@kong.gsfc.nasa.gov

V All the world is biscuit shaped. . .

[Martin Taylor 931228 13:00]
(Cliff Joslyn 931226, 10:35)

There is no simple straightforward way to make a quantitative
demonstration in a self-organized structure that I can think of at
the moment, and since such structures inherently demand a non-linear
effect somewhere along the line, all the problems of nonlinear
mathematics are likely to show up in any such system.

What about a convection cell in a heated fluid? Liquid at the bottom
is heated, it rises, it cools, it sinks. Heating causes rising, rising
causes cooling, cooling causes falling, falling causes heating.
Negative feedback. No control.

Yes, I expect that's a reasonable environment to look at. But you are
talking about the power source, and what is structured is the cell,
or rather, the set of cells. It's like the vortex. Slow heating doesn't
make cells, rapid heating makes for turbulence. The right power supply
can lead to a self-organized structure of cells. But the key word in
what you quoted from me was "quantitative." I think that this environment
is too complex for me to look at. I'm sure a lot of people have, though.
Maybe the desired analysis exists somewhere.

Martin