The Temperature is a numerical value between 0 and 100 that reflects the amount of perceptual organisation that is present in the Workspace. At the start of a problem, this value is high, depicting that little or no structure has been built in the Workspace, and drops as the solution progresses. This section describes the two main functions that the Temperature plays in the formation of a solution: the affect it has on the randomness of the system, and its role in the decision on when to stop and formulate a solution.
The
Randomness of the System
The first main role that Temperature has on the formation of a solution, is that it affects the amount of randomness that is present within the system. When the Temperature is high, it is viewed that there has been little structure build in the Workspace, and as a result, little information upon which to base good decisions. At this stage, which Codelets are chosen from the Coderack, and the decisions made by them are quite random, allowing many possible avenues to be explored in parallel. However, when the Temperature falls, there is more information by which informed decisions can be based, and the search is made to become more focused by allowing the certain emergent pressures to be given the influence that they deserve. That is, at this stage, the system becomes more deterministic, using the Coderack in a similar manner to a priority queue, in which the Codelets with the highest urgency are nearly always selected first.
Exercise 1. Load the group runs jffwww_100, jffwww_50 and jffwww_0, to see the effect of clamping the temperature at these levels. Compare these results to the original results, and comment about how the temperature affects the number of solutions that are derived, and the relative probability of the solutions.
You should have noted, that at high temperatures, many solutions are allowed to form that are quite peculiar. However, at low temperatures, the system is quite deterministic, and totally ignores some of the more interesting solutions. Comment on why you think the system should go from a random state initially (i.e. starting with a high Temperature) and become more focused as the solution progresses.
The Decision on When to Stop
The Temperature also plays an important role in determining when the system should stop and formulate an answer. This decision is probabilistic, so that even if no structure has been built, there is a probability that the system will stop and give a solution.
Exercise 2. Why is it important that the system be capable at stopping at a high temperature (i.e. when not much structure has been built)?
CHECKLIST
By the end of this section of the tutorial you should:
- know what the Temperature represents
- know the role that the Temperature takes in affecting the randomness of the system
- know the role of Temperature in determining when Copycat should stop and formulate a solution
