I was working a lot on XCS during the last two weeks and have some interesting results. Essential for the Algorithmic Description appears to be the mutation question. A sort of niche mutation appears to have been chosen in order to search in separate generality spaces. I.e., mutation is not allowed to change 1 to 0 or vice versa which means the mutated classifier stays within the current action set. However, in all comparisons that I made now between niche and unrestricted muation, the performance of XCS with niche mutation was worse or equal to the unrestricted mutation. I don't know if you have any results that actually support the niche muation process. It appears to me that when using unrestricted mutation and XCS found the necessary specificity or bits in one problem-subspace, it is helpful to sometimes try to mutate into another subspace (by changing a 1 to a 0 or vice versa) that might benefit from the knowledge of the first. ....
Q! << Click here to ask a new question on this paper.