Dear Bruce,

thank you for your answer.

... There is solid research only for the first type,

some strongly

suggestive results for the second type, and only the beginning of

discussion of the third type.

Ahh - ok - I understand ... this means the systems you are thinking about

are mainly internal controlled.

>My question for this list is the following:

>

>I am looking for a publication where it is made clear which

assumptions of

>the situation must be made that it is worth or even right to use a

>transformation model for this situation which is single

valued and closed?I don't understand the question.

What do you mean by a situation which is single valued and closed?

With single valued and closed I am refering to a transformation model

created by Ross Ashby centuries ago.

single valued means - every Operator (starting value) is transformed in

exactly one transform (end value)

closed means - during the Transformation there is no new element (setpoint)

added or taken away.

What is a transformation model? How does it relate to

negative feedback

control according to autonomously set reference values?

If my impression of your model is right, the relation between Ashby?s

transformation model and the negative feedback control system is, that

Ashby?s modell is interesting only for the part of your model where the

system tries to correct the error. The Operator would be the starting value

which has an error. This Error should be corrected through the

transformation from the starting value (whith error) to the end value

(without error).

For me there seems to be two ways to perform this transformation from

starting value to end value. Either it is clear how to perform a specific

transformation, then the system uses this "trivial" input-output

intervention to reach the aimed end value. Or it is not clear, then the

system has to work with smal steps to the aimed end value.

My questione for this transformation is the following: How can a system know

if it should use a "trivial" way or not when it assesses the situation?

Which criteria can a system use to know if a "trivial" transformation works

or not?

I hope the question is now more clear AND I still hope for an answer.

Thank you in advance.

Roland

## ···

When you ask about "assumptions of the situation" are you referring to

properties of the control system? Or are you referring to

properties of the

environment of the control system through which its negative feedback

control loop is (or loops are) closed?/Bruce Nevin