Approximations for ATSP with Parametrized Triangle Inequality

  • Authors:
  • L. Sunil Chandran;L. Shankar Ram

  • Affiliations:
  • -;-

  • Venue:
  • STACS '02 Proceedings of the 19th Annual Symposium on Theoretical Aspects of Computer Science
  • Year:
  • 2002

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Abstract

We give a constant factor ( 驴/1-驴 + 驴) approximation for the asymmetric traveling salesman problem in graphs with costs on the edges satisfying 驴-parametrized triangle inequality (驴-Asymmetric graphs) for 驴 驴 [1/2, 1). We also give an improvement of the algorithm with approximation factor approaching 驴/1-驴.We also explore the cmax/cmin ratio of edge costs in a general asymmetric graph. We show that for 驴 驴 [1/2, 1/驴3 ), cmax/cmin 驴 2驴3/1-3驴2, while for 驴 驴 [ 1/驴3, 1), this ratio can be arbitrarily large. We make use of this result to give a better analysis to our main algorithm. We also observe that when cmax/cmin 驴2/1-驴-驴2 with 驴 驴 (1/2, 驴5-1/2), the minimum cost and the maximum cost edges in the graph are unique and are reverse to each other.