Mutation is necessary to prevent areas of the search space being discarded.
The standard mutation operator chooses a single bit at random and swaps its value. Again, we did not allow changing the number of ones and zero’s.
Therefore, we applied ‘mutation inversion’: rather than selecting a single bit to mutate, inversion mutation finds just two random characters in the string and reverses them.
We further note that the mutation effect of this inverse mutation operator is uniformly spread over the chromosome and, in addition,generally lower that the mutation effect caused by the order based crossover operator mentioned above since the latter often causes mutations of several bits.