# SV: Session 1a

[From Bjoern Simonsen 980908. 2300 GMT]

[From Bill Powers (980905.0820 MDT)]

You can answer these questions privately just to see how you
fare, or send your answers to me to be posted anonymously and
discussed, or send them to me with questions to be answered
privately (but don't abuse that privilege).

Thank you, Bill. I prefere to send my answers to the newsgroup as
Rupert J. Young did 980907. In this way I send a signal to the group
where I stand. I am joyning the group to learn from all of you.

[From Bill Powers (980907.1123 MDT)]

I dont answer "1. List all the variable attributes (that you can) of an
apple" because I am thinking the same way as Ruper J. Young
showed 980907.

2. Can you control a car? Explain. What can you control about a
car? What is the main requirement on something to make it
controllable?

I control a certain car when I achieve and maintain a precelected
state of the controlling system through actions on the environment
that also cancel the effect of disturbance.( B:CP glosary page 283).

My system consists of a yellow Ford nn model 1996 driving
between A and B 981001 between 0600 and 2400 (MDT).

The helpvariabels are
a = a Ford nn model 1996
t = time = 0600<t<2400 (MDT)
d = date = 981001

I can control my precelected system by achieve and maintain
(renting) a yellow Ford nn model 1996, then start driving from
A 981001. 0600 MDT. I will adjust the speed to reach
B 2400 MDT. In this way will my helpvariabels be true. And if
they are true, I am controling the car.

The main requirement to control the system is to hold the
helpvariabels true.

3. Is it useful to say that someone is "angry?" Explain. What

It is not useful to say that a variabel in a system is "angry".
We have to say that the variabel angry = 7 (on a scale betwwen
0 an 9)

4. What's wrong from the simulation standpoint with saying " At
T-Zero, the spacecraft blasted off"?

T -zero is before control is "in business".
Is it more corect from a simulation standpoint to say
" At T = 981001.1500 MDT the spacecraft blasted off"

5...
= 25*F. Can we also say that the linkage force generated by the
cruise control results from the attainment of a certain speed
according to the second formula, F = S/25?

The formula F = S/25 is Ok to tell the relationship between F and S.
If we mean that S causes F we are wrong.

I look forward to further lessons

Regards

Bjoern Simonsen

[From Bill Powers (980908.1526 MDT)]

Bjoern Simonsen 980908. 2300 GMT--

I dont answer "1. List all the variable attributes (that you can) of an
apple" because I am thinking the same way as Ruper J. Young
showed 980907.

I hope you understood that Rupert was listing _variable attributes_ of the
apple, although as he mentioned they are not all perceivable, and as he
didn't mention they aren't all _easily_ affected by behavior, and thus
controllable.

2. Can you control a car? Explain. What can you control about a
car? What is the main requirement on something to make it
controllable?

I control a certain car when I achieve and maintain a precelected
state of the controlling system through actions on the environment
that also cancel the effect of disturbance.( B:CP glosary page 283).

The answer I wanted was NO, because you can control only variable
attributes of the car.

My system consists of a yellow Ford nn model 1996 driving
between A and B 981001 between 0600 and 2400 (MDT).

This refers to several attributes of the car: its color, its manufacturer,
its year of manufacture, its initial position (A), its final position (B),
and a time span during which the travel takes place. The color,
manufacturer, starting place, ending place, and time period are NOT
variables, at least without thinking up a somewhat unusual story (like
painting the car a different color). None of these is (normally) a variable
attribute of the car, is it? What you can control about the car is its
position (x,y), its velocity, the radius of curvature of its path, its
acceleration, and other such aspects of it that can vary with time under
ordinary conditions.

The helpvariabels are
a = a Ford nn model 1996
t = time = 0600<t<2400 (MDT)
d = date = 981001

These are constants, aren't they?

I can control my precelected system by achieve and maintain
(renting) a yellow Ford nn model 1996, then start driving from
A 981001. 0600 MDT. I will adjust the speed to reach
B 2400 MDT. In this way will my helpvariabels be true. And if
they are true, I am controling the car.

The only variable you have mentioned here that can actually vary is the speed.

The main requirement to control the system is to hold the
helpvariabels true.

I don't know what you mean by "helpvariables."

3. Is it useful to say that someone is "angry?" Explain. What

It is not useful to say that a variabel in a system is "angry".
We have to say that the variabel angry = 7 (on a scale betwwen
0 an 9)

That's what I had in mind.

4. What's wrong from the simulation standpoint with saying " At
T-Zero, the spacecraft blasted off"?

T -zero is before control is "in business".
Is it more corect from a simulation standpoint to say
" At T = 981001.1500 MDT the spacecraft blasted off"

The answer I was after was "at T = 0, the acceleration of the spacecraft
rose from zero to 1.8 gravities." "Blasting off" compresses a long
continuous process into a single event, turning a continuous variable into
a binary variable (blasted off vs. did not blast off).

5...
= 25*F. Can we also say that the linkage force generated by the
cruise control results from the attainment of a certain speed
according to the second formula, F = S/25?

The formula F = S/25 is Ok to tell the relationship between F and S.
If we mean that S causes F we are wrong.

Exactly what I wanted you to say. This point can be difficult to grasp,
especially when the formula results from a long derivation involving a
number of steps of algebra.

Best,

Bill P.