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Evolution Strategies

Evolutionary.ES — Type

Implementation of Evolution Strategy: (μ/ρ(+/,)λ)-ES

The constructor takes following keyword arguments:

  • initStrategy: an initial strategy description, (default: empty)
  • recombination: ES recombination function for population (default: first), see Crossover
  • srecombination: ES recombination function for strategies (default: first), see Crossover
  • mutation: Mutation function for population (default: first)
  • smutation: Mutation function for strategies (default: identity)
  • μ: the number of parents
  • ρ: the mixing number, ρ ≤ μ, (i.e., the number of parents involved in the procreation of an offspring)
  • λ: the number of offspring
  • selection: the selection strategy :plus or :comma (default: :plus)
source

Description

The Evolution Strategy is is an optimization technique based on ideas of evolution.

Evolution strategies use natural problem-dependent representations, and primarily Mutation and Selection, as search operators.

The canonical versions of the ES are denoted by (μ/ρ,λ)-ES and (μ/ρ+λ)-ES, respectively. Here μ denotes the number of parents, ρ ≤ μ the mixing number (i.e., the number of parents involved in the procreation of an offspring), and λ the number of offspring. The parents are deterministically selected (i.e., deterministic survivor selection) from the (multi-)set of either the offspring, referred to as comma-selection (μ<λ must hold), or both the parents and offspring, referred to as plus-selection [1].

References