Approximation Algorithms for Multi-Criteria Traveling Salesman Problems

  • Authors:
  • Bodo Manthey;L. Shankar Ram

  • Affiliations:
  • Yale University, Department of Computer Science, P.O. Box 208285, 06520-8285, New Haven, CT, USA;ETH Zürich, Institut für Theoretische Informatik, 8092, Zürich, Switzerland

  • Venue:
  • Algorithmica
  • Year:
  • 2009

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Abstract

We analyze approximation algorithms for several variants of the traveling salesman problem with multiple objective functions. First, we consider the symmetric TSP (STSP) with γ-triangle inequality. For this problem, we present a deterministic polynomial-time algorithm that achieves an approximation ratio of $\min\{1+\gamma,\frac{2\gamma^{2}}{2\gamma^{2}-2\gamma +1}\}+\varepsilon$and a randomized approximation algorithm that achieves a ratio of $\frac{2\gamma^{3}+2\gamma^{2}}{3\gamma^{2}-2\gamma +1}+\varepsilon$. In particular, we obtain a 2+ε approximation for multi-criteria metric STSP. Then we show that multi-criteria cycle cover problems admit fully polynomial-time randomized approximation schemes. Based on these schemes, we present randomized approximation algorithms for STSP with γ-triangle inequality (ratio $\frac{1+\gamma}{1+3\gamma -4\gamma^{2}}+\varepsilon$), asymmetric TSP (ATSP) with γ-triangle inequality (ratio $\frac{1}{2}+ \frac{\gamma^{3}}{1-3\gamma^{2}}+\varepsilon$), STSP with weights one and two (ratio 4/3) and ATSP with weights one and two (ratio 3/2).