Crossover (genetic algorithm)

Recombination as the generation of a new genome (also referred to as a branch genome) of (typically ) two parent genomes ( parental genomes ) means for evolutionary algorithms. A function that maps a permissible amount of parental genomes in a lot of store genomes, ie recombination function. A recombination function is a genetic operator.

Object of the recombination is to transfer good characteristics of two different parents to a child. As compared to algorithms that use only the mutation to alter the genome can thus be faster individuals are found, the two carry good properties A and B, if it were previously only individuals who had only A or B is either.

Good Rekombinationsfunktionen distinguished by the fact that they receive at least the good qualities of the parents and not so recombined that these properties are destroyed.

For various genomic and problem types, different types of recombinants are differently well:

Recombination of binary numbers ( bit strings )

In the recombination of binary numbers, the parental genomes are divided at one or more locations and assembled the branch genome from these parts.

An example is the recombination of two parental genomes, which are divided in two places:

Recombination of permutations

Recombination of permutations is specially designed for genomes that are permutations of the set itself.

An example of a recombination of permutations is the following method:

It is a second ( in a way inverse ) generate in this way a child, by inverting the list and the process of applying again.

Edge recombination

Another variant of the recombination of permutations is the Edge recombination, in which the neighborhood relationships between the elements of the parent genomes are maintained as much as possible. In the Edge -2 recombination thereby preferred are compounds that occur in both parental genomes. The Edge and Edge 3 -4- recombination in addition try to take advantage of additional neighborhoods by inversion of the genomes that were lost at the Edge 2 recombination. This method is particularly well suited for combinatorial optimization problems such as the Traveling Salesman Problem.

Recombination of trees

The recombination of trees is specially designed for genomes that are trees themselves.

An example of a recombination of trees is the following method:

• Given two parent trees (parental genomes ).
• Choose in each parent tree from a subtree.
• Swap these two subtrees.

The two then newly created trees are now the two child genomes.