2 Phenotype Diversity

Phenotype diversity represents the number of unique fitness values in a population. The number of possible fitness values is determined by the fitness function and varies between problem domains. For example, in the Parity problem, there is a finite number of possible fitness values that an individual can have. Instead, the fitness space is continuous in regression problems, but due to the precision of numbers, wrappers around operators (protected division for instance) and the presence of non-functional code it is possible for different trees to have the same fitness.