Strengthening Landmark Heuristics via Hitting Sets

  • Authors:
  • Blai Bonet;Malte Helmert

  • Affiliations:
  • Universidad Simón Bolívar, Venezuela, bonet@ldc.usb.ve;Albert-Ludwigs-Universität Freiburg, Germany, helmert@informatik.uni-freiburg.de

  • Venue:
  • Proceedings of the 2010 conference on ECAI 2010: 19th European Conference on Artificial Intelligence
  • Year:
  • 2010

Quantified Score

Hi-index 0.00

Visualization

Abstract

The landmark cut heuristic is perhaps the strongest known polytime admissible approximation of the optimal delete relaxation heuristic h+. Equipped with this heuristic, a best-first search was able to optimally solve 40% more benchmark problems than the winners of the sequential optimization track of IPC 2008. We show that this heuristic can be understood as a simple relaxation of a hitting set problem, and that stronger heuristics can be obtained by considering stronger relaxations. Based on these findings, we propose a simple polytime method for obtaining heuristics stronger than landmark cut, and evaluate them over benchmark problems. We also show that hitting sets can be used to characterize h+ and thus provide a fresh and novel insight for better comprehension of the delete relaxation.