Questions for Tuesday September 26

This is a long list of questions. Let's plan on discussing them on Tuesday,
so that you can turn in written answers on Thursday.

1. What is a major difference between Langton's CA and those of von Neumann,
Codd, and Conway? Do you think biological cells differ from von Neumann's, Codd's
and Conway's CA's in the same way?

2. Summarize the operation of Langton's self-reproducing configuration.

3. Starting on p. 124, Langton talks about limit points, limit cycles, and transients.
What do these terms mean? What is their interpretation in living systems?

4. Langton claims that long transients are a characteristic of
living systems. Do you agree or disagree with this claim, and why?

5. Compute the lambda value of the game of life. You can find the answer
in our readings, but show how the answer is actually derived.

6. In a CA where each cell has k possible states, and all states occur with the
same frequency as next states in the transition function, what is the lambda
value?

7. Give an example of a physical system and a parameter p of the system
such that the parameter has a critical point. That is, there is some value
c such that when p < c, the system behaves in a very different way than
when p > c.

8. Relate Wolfram's classes to Langton's classes based on his lambda parameter.

9. Describe Langton's method of exploring CA space so that the effect of
different lambda values could be tested. Do you think that his method produces
statistically reliable conclusions?

10. "Complexity" means many things to different groups of researchers.
To computer scientists, it is a measure of the difficulty of solving a 
problem based on the amount of computer time or space required. How does
Langton try to relate the computer science notion of complexity to
his classification scheme of CA? Do you agree with him? (There is,
of course, no absolute correct answer here.)

11. The cells in a CA may correspond to the cells in a living
organism, but if we are trying to model a single celled organism
like a bacterium with a CA, what do you think the cells in the CA
correspond to?

12. What are the arguments given for claiming that "life-like" behavior is found
in CA whose lambda value is in the "balanced" region?

13. Do you agree with these arguments or not? Why?