SAPIENT: Histogram Showing Improvement in PBIL Generated Strings Over Time

This histogram shows the increase of high-scoring strings generated by PBIL. The Eval axis shows the possible evaluations (averaged over four scenarios). Each unit on the Gen axis represents a generation of 100 cars (parameter bit-strings). The vertical axis num gives the number of cars in a particular generation which achieved a certain evaluation.

Note that most of the cars in the later generations receive high scores on the evaluation function. Due to the stochastic nature of the environment, and the randomness inherent in the PBIL algorithm, a small proportion of the vehicles in every generation receives poorer scores.