Fig. 3.

A basic sequence of operations leading to a selectable population. A population distributed over the genotype space $\left(\mathcal{G}\right)$ is assigned phenotype values $\left(\mathcal{P}\right)$ via the genotype–phenotype mapping $\phi$, which are then interpreted by f into objective function values $\left(\mathcal{O}\right)$. Variation operators generate new variation at the genotypic level and selection operators act at the level of the objective function, generating a new population in $\mathcal{G}$. The $\mathcal{W}$ line represents the probability for this individual to be present in the next generation, which is a consequence of the selection operators used. This is typically called “fitness” in PG and is related to the reproductive rate in EC.