The mutation of enumerated chromosomes differs from the mutation of binary chromosomes.  Instead of reversing one gene value of a binary chromosome, the mutation operator swaps two genes of an enumerated chromosome.  Figure A.6 illustrates the mutation of an enumerated chromosome.

Figure A.6  Example of the mutation operator for an individual with an 8-gene enumerated chromosome.

In the GeneHunter DLL, a mutation rate parameter gives the probability of swapping enumerated chromosome genes.  If we set the mutation rate to zero, mutation is turned off, while a mutation rate of 1 will lead to a completely stochastic search with no succession from generation to generation.  Details on setting the mutation rate are included in Chapter 8, Programming Reference, in the SetOperators and SetEnumOperators functions.

We cannot answer the question "Is 0.001 a high mutation rate?” because it all depends upon the problem to be optimized.

Note: The GeneHunter DLL allows the user to specify one rate of mutation for continuous (binary) and another rate for enumerated chromosomes.