An evolutionary algorithm which generates each individual from some encoded form known as a “chromosome” or “genome”. Chromosomes are combined or mutated to breed new individuals. “Crossover”, the kind of recombination of chromosomes found in sexual reproduction in nature, is often also used in Gas. Here, an offspring’s chromosome is created by joining segments chosen alternately from each of two parents’ chromosomes which are of fixed length. Gas are useful for multidimensional optimisation problems in which the chromosome can encode the values for the different variables being optimised.