The decimal number 935 might be coded as the binary string 1110100111.
The path from London to Paris to Munich to Venice might be coded as LPMV.
The collection of all individuals (that is, potential solutions) together is known as a population. All of the individuals "alive" at a given time form a generation.
The two main recombination techniques are crossover and mutation.
Crossover produces two children by cutting
the chromosomes of
each parent at random crossover points and rearranging them to create
offspring, as shown by the accompanying animation.
This animation illustrates one point crossover, named as such because each of the parents is cut in one place. A GA using two point crossover cuts the parent strings in two places before rearranging them. Another technique, uniform crossover, forms the child by randomly selecting either one of the corresponding parents' genes for each gene to be filled on the child's chromosome, as illustrated below. Two point crossover and uniform crossover are sometimes considered more productive than simple one point crossover.
Of the individuals selected for reproduction (as opposed to those usually unfit individuals discarded before this stage), not all may actually undergo crossover. Between 100% to 60% of selected individuals in each generation reproduce sexually via crossover. The remainder are duplicated or cloned, so that the child has exactly the same chromosome as the parent.
After crossover and cloning are complete, a small
number (often less
than 1%) of individuals suffer mutation. A mutated individual
has one or more of its genes altered, as demonstrated in the animation.
Mutation helps the GA avoid premature
There is an approximately 275KB animated GIF showing the entire process of creating a new generation of solutions with selection, crossover, and mutation. Highly Recommended.
Also see some variations to the
simple reproduction and selection described above.
Back to Main