[galib] Bug in CycleCrossover
Bobbadoc at aol.com
Tue Oct 11 22:30:48 EDT 2005
I believe that the implementation of CycleCrossover in GA1DArrayGenome.c
contains an error.
Briefly, I believe that the variable "current" in the segment of code
if (c1 && c2)
should be reinitialized before the "bro" child genome is created, that is,
that the line
current = 0;
should be added between
As the code reads now, the cycle for "bro" is resought starting at the last
new cycle-member's position in the earlier code (denoted by the value of
<current> left over from seeking the cycle during creation of the "sis" genome)
but the corresponding mask bit is not set, as it should be (rather, the mask
bit at position 0 is set, as it was in the code for "sis"). As a result, the
"bro" child, which presumably is supposed to represent a permutation, may
contain a duplicate value (and a corresponding omission). On a subsequent
crossover attempt, the bogus chromosome can cause the program to hang up,
presumably in an infinite loop.
If anyone thinks that I am in error or would like a more detailed
explanation, please let me know. I have very much enjoyed working with this library.
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