Computing knapsack solutions with cardinality robustness

  • Authors:
  • Naonori Kakimura;Kazuhisa Makino;Kento Seimi

  • Affiliations:
  • Department of Mathematical Informatics, University of Tokyo, Tokyo, Japan;Department of Mathematical Informatics, University of Tokyo, Tokyo, Japan;Department of Mathematical Informatics, University of Tokyo, Tokyo, Japan

  • Venue:
  • ISAAC'11 Proceedings of the 22nd international conference on Algorithms and Computation
  • Year:
  • 2011

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Abstract

In this paper, we study the robustness over the cardinality variation for the knapsack problem. For the knapsack problem and a positive number α ≤1, we say that a feasible solution is α-robust if, for any positive integer k , it includes an α -approximation of the maximum k -knapsack solution, where a k -knapsack solution is a feasible solution that consists of at most k items. In this paper, we show that, for any ε 0, the problem of deciding whether the knapsack problem admits a (ν +ε )-robust solution is weakly NP-hard, where ν denotes the rank quotient of the corresponding knapsack system. Since the knapsack problem always admits a ν -robust knapsack solution [7], this result provides a sharp border for the complexity of the robust knapsack problem. On the positive side, we show that a max-robust knapsack solution can be computed in pseudo-polynomial time, and present a fully polynomial time approximation scheme (FPTAS) for computing a max-robust knapsack solution.