seven commonly used diversity mechanisms and prove rigorous run time bounds for the (μ+ 1) GA using uniform crossover on the fitness function Jump k. All previous results in this context only hold for unrealistically low crossover probability pc= O (k/n), while we give analyses for the setting of constant pc< 1 in all but one case. Our bounds show a dependence on the problem size~ n, the jump length k, the population size μ, and the …
Population diversity is essential for the effective use of any crossover operator. We compare seven commonly used diversity mechanisms and prove rigorous run time bounds for the (μ+1) GA using uniform crossover on the fitness function Jumpk. All previous results in this context only hold for unrealistically low crossover probability pc=O(k/n), while we give analyses for the setting of constant pc < 1 in all but one case. Our bounds show a dependence on the problem size~, the jump length k, the population size μ, and the crossover probability pc. For the typical case of constant k > 2 and constant pc, we can compare the resulting expected optimisation times for different diversity mechanisms assuming an optimal choice of μ:
O}(nk-1) for duplicate elimination/minimisation,
O}(n2 log n) for maximising the convex hull,
O(n log n) for det. crowding (assuming pc = k/n),
O(n log n) for maximising the Hamming distance,
O(n log n) for fitness sharing,
O(n log n) for the single-receiver island model.
This proves a sizeable advantage of all variants of the (μ+1) GA compared to the (1+1) EA, which requires θ(nk). In a short empirical study we confirm that the asymptotic differences can also be observed experimentally.