Calculating the Expected Loss of Diversity of Selection Schemes

This paper concerns a measure of selective pressure, called "loss of diversity," that denotes the proportion of unselected individuals during the selection phase. We probabilistically calculate the expected value and variance of loss of diversity in tournament selection, truncation selection, linear ranking selection, and exponential ranking selection. From numerical results, we observe that in tournament selection, many more individuals are expected to be lost than with Blickle and Thiele's static estimate. We also observe that tournament and exponential ranking schemes potentially bring about nearly equivalent selection behaviors but have different types of control parameters.