Greedy Hypervolume Subset Selection in the Three-Objective Case


Given a non-dominated point set X subset of R-d of size n and a suitable reference point r(2) is an element of R-d, the Hypervolume Subset Selection Problem (HSSP) consists of finding a subset of size k <= n that maximizes the hypervolume indicator. It arises in connection with multiobjective selection and archiving strategies, as well as Pareto-front approximation post-processing for visualization and/or interaction with a decision maker. Efficient algorithms to solve the HSSP are available only for the 2-dimensional case, achieving a time complexity of O (n(k + log n)). In contrast, the best upper bound available for d > 2 is O (n(d/2) log n + n(n-k)). Since the hypervolume indicator is a monotone submodular function, the HSSP can be approximated to a factor of (1 - 1/e) using a greedy strategy. Such a greedy algorithm for the 3-dimensional HSSP is proposed in this paper. The time complexity of the algorithm is shown to be O (n(2)), which considerably improves upon recent complexity results for this approximation problem.