A First Runtime Analysis of the NSGA-II on a Multimodal Problem

Benjamin Doerr, Zhongdi Qu

Abstract: Very recently, the first mathematical runtime analyses of the multiobjective evolutionary optimizer nondominated sorting genetic algorithm II (NSGA-II) have been conducted. We continue this line of research with a first runtime analysis of this algorithm on a benchmark problem consisting of multimodal objectives. We prove that if the population size $N$ is at least four times the size of the Pareto front, then the NSGA-II with four standard ways to select parents, bitwise mutation, and crossover with rate less than one, optimizes the OneJumpZeroJump benchmark with jump size $2 \le k \le n/4$ in time $O(N n^{k})$ . When using fast mutation instead of bitwise mutation this guarantee improves by a factor of $k^{\Omega (k)}$ . Overall, this work shows that the NSGA-II copes with the local optima of the OneJumpZeroJump problem at least as well as the global SEMO algorithm.