Restricted permutation allows two genes occupying any positions within a particular multigene family to exchange positions. This operator might also be useful for making finer adjustments when combined with inversion, but if used as the only source of genetic variation, its performance is very poor (see
Figure 6.2).
The restricted permutation operator randomly chooses the chromosome, the multigene family to be modified and the genes to be exchanged. Furthermore, each chromosome is only modified once by this operator.
Consider the following chromosome composed of two multigene families:
| 01234567890123456780123456789012345678 |
|
|
ikmosfghdeqprljncabLNJIHGCDPSRQOBKMFAE |
(6.7) |
Suppose, for instance, that genes 6 (“C”) and 15 (“M”) in
MGF2 were chosen to be exchanged. Then the following chromosome is formed:
| 01234567890123456780123456789012345678 |
|
|
ikmosfghdeqprljncabLNJIHGMDPSRQOBKCFAE |
(6.8) |
Restricted permutation, if used at small rates and in combination with inversion, might be useful for making finer adjustments. But, again, for all the problems analyzed in this chapter, when restricted permutation is used in conjunction with inversion the success rate decreases slightly.
|