Information Technology Reference
In-Depth Information
Consider, for instance, the chromosome below composed of two multigene
families:
01234567890123456780123456789012345678
rpifg
h
asbdeocjknlqmQSKLHCIGDONPFEJMBRA
(11.7)
Suppose gene 5 in MGF
1
was selected to transpose to site 14 (between genes
13 and 14). Then gene 5 (“h”) is deleted at the place of origin and inserted
between genes “j” and “k”, giving:
01234567890123456780123456789012345678
rpifgasbdeocj
h
knlqmQSKLHCIGDONPFEJMBRA
(11.8)
The deletion/insertion of genes when combined with the most powerful
operator (inversion) might be useful for finer adjustments. However, for all
the problems analyzed in this chapter, the performance was higher when
inversion alone was used in the search.
11.2.3 Restricted Permutation
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 11.3 above).
The restricted permutation operator randomly chooses the chromosome,
the multigene family to be modified and the genes to be exchanged. Further-
more, each chromosome is only modified once by this operator.
Consider, for instance, the following chromosome composed of two
multigene families:
01234567890123456780123456789012345678
ikmosfghdeqprljncabLNJIHG
C
DPSRQOBK
M
FAE
(11.9)
Now suppose that genes 6 (“C”) and 15 (“M”) in MGF
2
were chosen to be
exchanged. Then the following chromosome is formed:
01234567890123456780123456789012345678
ikmosfghdeqprljncabLNJIHG
M
DPSRQOBK
C
FAE
(11.10)
Restricted permutation, if used at small rates and in combination with
inversion, might be useful for making finer adjustments. But, again, for all
