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Next: Genetic Evolution Up: Mean Field Theory of Previous: The Convergence-Time Measure

Results

Our results are shown in figures 2-4. In figure 2, the convergence time in 10th-order mean field theory is studied for rules of radius 2-4. Increasing line width indicates increasing radius. Many rules were generated at each possible value of , and the convergence-time averaged over the set of rules with a given value. For each radius a broad peak in convergence time is found. The location and width of these peaks is in close correspondence with previous empirical results using the parameter, e.g. those Li et al. [LPL90]. Thus, our convergence-time criterion provides an analytic measure of complexity in quantitative agreement with empirical measures.

Figure 3 shows an example of how the mean field theory can be used to refine the parameter analysis. Here two mean field parameters, , and for radius-3 rules are varied, while the other parameters are held constant. To generate this figure, all rules from figure 2 which happened to fall in this hyperplane in mean-field parameter space were selected. The height of the surface is this figure gives the average convergence time for rules with specified mean-field parameter values. Note that by restricting consideration to this hyperplane, we greatly sharpen the region in which rules of high convergence time are found.

This point is emphasized in figure 4. In this figure, the hyperplane is projected into the parameter space. For this hyperplane, =. It is seen that the sharp mean-field peak is in the same location as the parameterized peak. By increasing the order of the mean field theory, we should be able to locate with greater precision the region in parameter space in which high-convergence- time reside.



Howard A. Gutowitz
Wed Mar 29 16:14:50 MST 1995