machines is modified only the modules and chromosome portions relating to that machine need to be changed box 207 outputs the measure of fitness to the ga 101 which iterates to the next step the output can be in the form of a cost vector having three positions where cost 0 is a fail code which is the highest one encountered for any machine type in the line the code will have one of two values as follows cost 1 is the cycle time for the slowest machine in the production line if cost 0 1 then cost 1 is the number of parts that could not be placed this 3 part cost vector is used hierarchically by the ga that is when comparing two chromosomes the better chromosome is the one with the lower cost where comparing starts at level 0 and proceeds to the next level only if there is a tie an infeasible layout from any machine type module 204 206 will have a cost 0 of one if both chromosomes yield infeasible layouts the one with the fewest parts not placed is better if both chromosomes represent feasible solutions the cycle times cost 1 are compared and if these are equal the number of pick positions roughly equivalent to the number feeders required is used to break ties if all three scores are equal the chromosomes are considered equally fit this scheme allows the ga 101 to make progress solving very difficult problems where feasible solutions are.