# File lib/ai4r/genetic_algorithm/genetic_algorithm.rb, line 204
      def self.mutate(chromosome)
        if chromosome.normalized_fitness && rand < ((1 - chromosome.normalized_fitness) * 0.3)
          data = chromosome.data
          index = rand(data.length-1)
          data[index], data[index+1] = data[index+1], data[index]
          chromosome.data = data
          @fitness = nil
        end
      end