Parameterized average-case complexity of the hypervolume indicator

  • Authors:
  • Karl Bringmann;Tobias Friedrich

  • Affiliations:
  • Max-Planck-Institut für Informatik, Saarbrücken, Germany;Friedrich-Schiller-Universität, Jena, Germany

  • Venue:
  • Proceedings of the 15th annual conference on Genetic and evolutionary computation
  • Year:
  • 2013

Quantified Score

Hi-index 0.00

Visualization

Abstract

The hypervolume indicator (HYP) is a popular measure for the quality of a set of n solutions in ℜRd. We discuss its asymptotic worst-case runtimes and several lower bounds depending on different complexity-theoretic assumptions. Assuming that P ≠ NP, there is no algorithm with runtime poly(n,d). Assuming the exponential time hypothesis, there is no algorithm with runtime no(d). In contrast to these worst-case lower bounds, we study the average-case complexity of HYP for points distributed i.i.d. at random on a d-dimensional simplex. We present a general framework which translates any algorithm for HYP with worst-case runtime n f(d) to an algorithm with worst-case runtime n f(d)+1 and fixed-parameter-tractable (FPT) average-case runtime. This can be used to show that HYP can be solved in expected time O(d d2/2, n + d, n2), which implies that HYP is FPT on average while it is W[1]-hard in the worst-case. For constant dimension d this gives an algorithm for HYP with runtime O(n2) on average. This is the first result proving that HYP is asymptotically easier in the average case. It gives a theoretical explanation why most HYP algorithms perform much better on average than their theoretical worst-case runtime predicts.