Re: [asa] Guided evolution mechanism?

Hi Dave,

Nice response - it hit the list whilst I was composing mine - otherwise I might not have bothered!

Actually, the subject raises some interesting questions which I'm going away to muse upon. So perhaps more later.

Blessings,
Murray

Dave Wallace wrote:
> Christine Smith wrote:
>> Can someone provide some more background on "control theory"?
>>
> Christine:
>
> Look at
> http://en.wikipedia.org/wiki/Control_theory
> for a good description of Control theory is.
>
> From wiki, a typical control application looks like:
> <http://en.wikipedia.org/wiki/Image:Feedback_loop_with_descriptions.svg>
> <http://en.wikipedia.org/wiki/Image:Feedback_loop_with_descriptions.svg>
> The concept of the feedback loop to control the dynamic behaviour of the
> system: this is negative feedback, because the sensed value is
> subtracted from the desired value to create the error signal which is
> amplified by the controller.
> ...
>
>
> Take the case of a car cruise control. The Reference is the desired
> speed. The controller interacts with the car system by changing the
> position of the throtle. The speedometer (logically) is the sensor and
> feeds the actual speed back to the Measured error point where it is
> subtracted from the desired speed and feed into the controller.
> Of course the actual system is likely to be more complex than I have
> described in that the difference between the reference speed and the
> actual speed is likely allowed to reach some small difference prior to
> actually increasing/decreasing the throttle. Otherwise one would likely
> get surging where the fuel going to the engine was constantly being
> changed.
> The study of the behaviors of such systems is called control theory and
> is quite complex in many cases as instabilities can tend towards
> oscillations or vary large values.
>
> Feedback is a very powerful mechanism and I tend to think of the
> Variation/Natural Selection mechanism in those terms.
> Dave W
>
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Received on Wed Nov 12 14:05:18 2008