Occasionally, during evolution, a GA can become “stuck”, i.e., the GA is not producing more fit individuals, even though it is nowhere near an optimum fitness.  The extinction operator may help when this situation occurs.  The extinction operator is like the near biological extinction of a population.  It can be thought of as a massive plague or nuclear war which kills all but the most fit individuals.  The population is then refreshed with mutated copies of that most fit individual.  The SetExtinction function (refer to Chapter 8) sets the parameters of the extinction operator.  The user may specify the number of generations after which the extinction occurs if there has been no progress in that number of generations.  The programmer may also specify the amount of mutation that should occur with the most fit individual.