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(HX)
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Keywords
information exchanging,
information destruction,
convergence speed,
non-disruptive crossover,
optimal crossover points
Motivation
●
Reduction of the destructive action of a multi-point crossover
operator resulting from random selection of crossover points
Source text
●
Park J.,
Park J., Lee Ch.,
Han M. (1993),
Robust and Efficient Genetic Crossover Operator: Homologous
Recombination, in Proceedings of 1993 International Joint
Conference on Neural Networks,
pp. 2975-2978
WEB:
http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=714347
Read also
●
Beyer
H.-G. (1995),
Toward a Theory of Evolution Strategies: On the Benefits of Sex the
(μ/μ,lambda)
Theory, in Evolutionary Computation, vol. 3(1), pp. 81-111
WEB:
http://citeseer.ifi.unizh.ch/361714.html
http://citeseer.ist.psu.edu/361714.html
See also
●
Spontaneous
Crossover
●
Circle-ring
Crossover
●
Sufficient Exchanging
●
Intermediate Crossover
●
Intermediate
Crossover2
●
Adaptive Number of Crossover Points
Algorithm
1.
select two parents A(t)
and B(t) from a current population P(t)
2.
randomly choose m crossover points {pc1,...,pcm}
3.
create two offspring A(t+1)
and B(t+1) by restricted m-point
crossover
as follows:
4.
for every pair of strings STA=(apck(t),...,apck+1(t))
and
STB=(bpck(t),...,bpck+1(t))
between two successive crossover points
pck and pck+1 do:
5.
if length_of_STA (=
length_of_STB ) ≥ w
then
6.
compute the degree of similarity DS
of strings STA and STB
as follows:
7.
number_of_1 = 0
8.
for i = k to
k+w do
9.
if
apci(t)
XOR bpci(t) =1
then
10.
number_of_1 = number_of_1 + 1
11.
end if
12.
end do
13.
DS = number_of_1/length_of_STA
14.
if DS ≥
u then
15.
swap bits
16.
else
17.
do nothing
18.
end if
19.
else
20.
do nothing
21.
end if
22.
end do
where:
w
and u parameters of the method
Comments
●
The HX operator is based on the standard
k-Point Crossover operator. Introduced modification relies on the
fact that only strings of bits which are at least of a certain length
(row: 5) or of an admissible degree of similarity (row: 14) are allowed
to crossover. Determination of the degree of similarity is based on the
XOR operator (rows: 9-13).
●
This strategy is aimed at transferring (hence also protecting)
strings with specified parameters to the next generation.
●
In HX the value of
w
and
u
is determined à priori as constant or dynamically changed (increased) in
the GA run.
Experiment domains
●
De Jongs function (F1)
Compared to
●
k-Point Crossover
●
Uniform Crossover
●
Intermediate Crossover
●
Intermediate
Crossover2 |
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