Information Technology Reference
In-Depth Information
C
1
= {-0.273, -0.376, -1.089, -1.544, -0.668, 1.969, -1.978, -1.192, -1.930, 0.053}
C
2
= {1.499, -0.346, 0.391, -0.232, 0.307, 1.586, -0.300, 0.729, -0.885, -0.1897}
Suppose now that the sequence “250” in gene 2 was chosen as a transposon
and that the insertion site was bond 1 in Dc (between positions 10 and 11).
Then the following chromosome is obtained:
0123456789012345601234567890123456
+--+?aa?aaa655501-a+?-?aaa??
250
772
(5.11)
Note that, before moving to the insertion site, the transposon is deleted at the
place of origin, thus maintaining the Dc length.
As you can see in Figure 5.6, these two chromosomes encode slightly
different solutions because the random numerical constants were moved
around by the transposition operator and, as a result, not only a new constant
was tested (the constant 0.391) but also different interactions were tested for
old constants; in this case, the constant 1.586 was moved around in sub-ET
2
.
5.4.4 Direct Mutation of RNCs
We have already seen that all the genetic operators contribute, directly or
indirectly, to move the random numerical constants around. And, in fact, this
permanent shuffling of RNCs is more than sufficient to allow an efficient
evolution of good solutions as the appropriate number of RNCs can be gen-
erated at the beginning of each run. Notwithstanding, we can also implement
a special mutation operator that replaces the value of a particular numerical
constant by another.
This operator, called direct mutation of RNCs, randomly selects particu-
lar targets in the arrays where the RNCs are kept, and randomly generates a
new numerical constant.
Consider, for instance, the two-genic chromosome below with
h
= 5 and
its arrays of random numerical constants:
0123456789012345601234567890123456
**a//aa?a??461226*a+*?a?aaaa406961
(5.12)
C
1
= {0.139, -0.299, -1.024, -0.330,
0.510
, -1.864, 1.008, -0.712, -1.740, 1.552}
C
2
= {-0.986, -0.147, -1.113, -1.577, 0.210,
0.218
, 1.705,
-0.770
, 1.845, 1.954}
Now suppose that a mutation occurred at position 4 in C
1
, changing the con-
stant 0.510 occupying that position by -0.256, and that two other mutations
